Pharmaceutics

Published by MDPI

Online ISSN: 1999-4923

Articles


Table 1 . Estimated molar solubilisation capacity and CMC. 
Figure 1. Schematic UV imaging dissolution system. 
Table 2 . CBZ-NIC cocrystal eutectic point, cocrystal solubility and solubility ratio. 
Figure 2. Apparent solubility of CBZ as a function of surfactant concentration. 
Figure 3. Apparent CBZ solubility profile as a function of NIC concentration after 72 h. 
Influence of Sodium Lauryl Sulfate and Tween 80 on Carbamazepine–Nicotinamide Cocrystal Solubility and Dissolution Behaviour
  • Article
  • Full-text available

December 2013

·

1,295 Reads

·

·

The influence of the surfactants of sodium lauryl sulfate (SLS) and Tween 80 on carbamazepine-nicotinamide (CBZ-NIC) cocrystal solubility and dissolution behaviour has been studied in this work. The solubility of the CBZ-NIC cocrystal was determined by measuring the eutectic concentrations of the drug and the coformer. Evolution of the intrinsic dissolution rate (IDR) of the CBZ-NIC cocrystal was monitored by the UV imaging dissolution system during dissolution. Experimental results indicated that SLS and Tween 80 had little influence upon the solubility of the CBZ-NIC cocrystal but they had totally opposite effects on the IDR of the CBZ-NIC cocrystal during dissolution. SLS significantly increased the IDR of the CBZ-NIC cocrystal while Tween 80 decreased its IDR.
Download
Share

Figure 1. Chemical structures of (a) fluorometholone and (b) dexamethasone. 
Steroid Nanocrystals Prepared Using the Nano Spray Dryer B-90

March 2013

·

328 Reads

The Nano Spray Dryer B-90 offers a new, simple, and alternative approach for the production of drug nanocrystals. In this study, the preparation of steroid nanocrystals using the Nano Spray Dryer B-90 was demonstrated. The particle size was controlled by selecting the mesh aperture size. Submicrometer steroid particles in powder form were successfully obtained. These nanoparticles were confirmed to have a crystal structure using powder X-ray diffraction pattern analysis. Since drug nanocrystals have recently been considered as a novel type of drug formulation for drug delivery systems, this study will be useful for nano-medical applications.

Figure 7. ( A ) Inhibition of ABCG2-mediated MTX transport by gefitinib. Experimental procedures and conditions are described previously [47]. The chemical structure of gefitinib is depicted in this figure. ( B ) Relationship between observed and predicted values in the inhibition of ABCG2-mediated MTX transport by different test compounds. The inhibition by gefitinib is indicated by an open circle ( ○ ). Data are from [47]. 
Transporter-Mediated Drug Interaction Strategy for 5-Aminolevulinic Acid (ALA)-Based Photodynamic Diagnosis of Malignant Brain Tumor: Molecular Design of ABCG2 Inhibitors

December 2011

·

79 Reads

·

·

·

[...]

·

Photodynamic diagnosis (PDD) is a practical tool currently used in surgical operation of aggressive brain tumors, such as glioblastoma. PDD is achieved by a photon-induced physicochemical reaction which is induced by excitation of protoporphyrin IX (PpIX) exposed to light. Fluorescence-guided gross-total resection has recently been developed in PDD, where 5-aminolevulinic acid (ALA) or its ester is administered as the precursor of PpIX. ALA induces the accumulation of PpIX, a natural photo-sensitizer, in cancer cells. Recent studies provide evidence that adenosine triphosphate (ATP)-binding cassette (ABC) transporter ABCG2 plays a pivotal role in regulating the cellular accumulation of porphyrins in cancer cells and thereby affects the efficacy of PDD. Protein kinase inhibitors are suggested to potentially enhance the PDD efficacy by blocking ABCG2-mediated porphyrin efflux from cancer cells. It is of great interest to develop potent ABCG2-inhibitors that can be applied to PDD for brain tumor therapy. This review article addresses a pivotal role of human ABC transporter ABCG2 in PDD as well as a new approach of quantitative structure-activity relationship (QSAR) analysis to design potent ABCG2-inhibitors.

Table 1 . Summary of probe sets in the Canine GeneChip used for analysis in this study. 
Figure 1. Principal Component Analysis (PCA) of gene expression profiles of MDCK cells in various culture conditions. Expression values from a total of 5554 confirmed probe sets that were considered present in at least one condition were used for analysis. 
Figure 2. Expression profiles of ABC transporter genes involved in the drug absorption process. 
Figure 4. Expression profiles of CYP enzymes in MDCK cells grown under various conditions. 
Expression Profile of Drug and Nutrient Absorption Related Genes in Madin-Darby Canine Kidney (MDCK) Cells Grown under Differentiation Conditions

December 2012

·

482 Reads

The expression levels of genes involved in drug and nutrient absorption were evaluated in the Madin-Darby Canine Kidney (MDCK) in vitro drug absorption model. MDCK cells were grown on plastic surfaces (for 3 days) or on Transwell® membranes (for 3, 5, 7, and 9 days). The expression profile of genes including ABC transporters, SLC transporters, and cytochrome P450 (CYP) enzymes was determined using the Affymetrix® Canine GeneChip®. Expression of genes whose probe sets passed a stringent confirmation process was examined. Expression of a few transporter (MDR1, PEPT1 and PEPT2) genes in MDCK cells was confirmed by RT-PCR. The overall gene expression profile was strongly influenced by the type of support the cells were grown on. After 3 days of growth, expression of 28% of the genes was statistically different (1.5-fold cutoff, p < 0.05) between the cells grown on plastic and Transwell® membranes. When cells were differentiated on Transwell® membranes, large changes in gene expression profile were observed during the early stages, which then stabilized after 5-7 days. Only a small number of genes encoding drug absorption related SLC, ABC, and CYP were detected in MDCK cells, and most of them exhibited low hybridization signals. Results from this study provide valuable reference information on endogenous gene expression in MDCK cells that could assist in design of drug-transporter and/or drug-enzyme interaction studies, and help interpret the contributions of various transporters and metabolic enzymes in studies with MDCK cells.

Live Cell in Vitro and in Vivo Imaging Applications: Accelerating Drug Discovery

December 2011

·

802 Reads

Dynamic regulation of specific molecular processes and cellular phenotypes in live cell systems reveal unique insights into cell fate and drug pharmacology that are not gained from traditional fixed endpoint assays. Recent advances in microscopic imaging platform technology combined with the development of novel optical biosensors and sophisticated image analysis solutions have increased the scope of live cell imaging applications in drug discovery. We highlight recent literature examples where live cell imaging has uncovered novel insight into biological mechanism or drug mode-of-action. We survey distinct types of optical biosensors and associated analytical methods for monitoring molecular dynamics, in vitro and in vivo. We describe the recent expansion of live cell imaging into automated target validation and drug screening activities through the development of dedicated brightfield and fluorescence kinetic imaging platforms. We provide specific examples of how temporal profiling of phenotypic response signatures using such kinetic imaging platforms can increase the value of in vitro high-content screening. Finally, we offer a prospective view of how further application and development of live cell imaging technology and reagents can accelerate preclinical lead optimization cycles and enhance the in vitro to in vivo translation of drug candidates.

Diagram illustrating the two discussed routes of triamcinolone acetonide (TA) administration, sub-Tenon’s infusion (STI) and intravitreal injection (IVI). STI placement is between Tenon’s capsule and the sclerotic coat of the eye. This is accomplished by making a small incision and placing a blunt curved cannula towards the posterior pole of the eye and infusing slowly. IVI is placed 3 to 4 mm posterior to the limbus and in the inferotemporal region.
Delivery of Intraocular Triamcinolone Acetonide in the Treatment of Macular Edema

December 2012

·

255 Reads

Macular edema (ME) is one of the eventual outcomes of various intraocular and systemic pathologies. The pathogenesis for ME is not yet entirely understood; however, some of the common risk factors for its development have been identified. While this investigation will not discuss the numerous etiologies of ME in detail, it appraises the two most widely studied delivery modalities of intraocular corticosteroids in the treatment of ME-intravitreal injection (IVI) and sub-Tenon's infusion (STI). A thorough review of the medical literature was conducted to identify the efficacy and safety of IVI and STI, specifically for the administration of triamcinolone acetonide (TA), in the setting of ME in an attempt to elucidate a preferred steroid delivery modality for treatment of ME.

Table 3 . pH-Triggered release of methotrexate from PEGylated liposomes. 
Figure 3. Effect of the mole percentage of 1 on the pH-triggered release of ANTS from 1/POPC/PEG-ceramide fliposomes. The release is presented: (A) in relative light units (RLU) and (B) in percent of leakage. The molar ratio 1/POPC/PEG-ceramide: a, 25/70/5; b, 50/45/5; c, 75/20/5; d, 90/5/5. Arrows indicate addition of acid to lower pH from 7.4 to 5.1; asterisks indicate addition of C 12 E 8 for fliposomes permeation. The x-axes are in relative time scales to fit all the traces into the figure. 
Figure 4. Release of ANTS from fliposomes containing (A) 1/POPC/PEG-ceramide or (B) 1/POPC/PEG-DPPE upon lowering pH from 7.4 to 5.1 (arrows). The x-axes are in relative time scales to fit all the traces into the figure. 
Figure 5. pH-triggered release of ANTS from 1/POPC/PEG-ceramide fliposome (50/45/5) at (a) 0.12 mM and (b) 0.024 mM total lipid concentrations. Arrows: pH lowered from 7.4 to 5.1; asterisk: fliposome permeated by the detergent C 12 E 8. The release is expressed: (A) in relative light units (RLU), and (B) in percent of leakage. The x-axes are in relative time scales to fit all the traces into the figure. 
Fliposomes: pH-Sensitive Liposomes Containing a trans-2-morpholinocyclohexanol-Based Lipid That Performs a Conformational Flip and Triggers an Instant Cargo Release in Acidic Medium

December 2011

·

183 Reads

Incorporation of a pH-sensitive conformational switch into a lipid structure enables a drastic conformational flip upon protonation that disrupts the liposome membrane and causes rapid release of cargo specifically in areas of increased acidity. pH-sensitive liposomes containing the amphiphile (1) with trans-2-morpholinocyclohexanol conformational switch, a phospholipid, and a PEG-lipid conjugate were constructed and characterized. The optimized composition-1/POPC/PEG-ceramide (50/45/5)-could be stored at 4 °C and pH 7.4 for up to 1.5 years, and was stable in blood serum in vitro after 48 h at 37 °C. Liposomes loaded with ANTS/DPX or methotrexate demonstrated an unusually quick content release (in a few seconds) at pH below 5.5, which was independent of inter-liposome contact. The pH-titration curve for the liposome leakage paralleled the curve for the acid-induced conformational flip of 1 studied by 1H-NMR. Freeze-fracture electron microscopy images showed budding and division of the bilayer at pH 5.5. A plausible mechanism of pH-sensitivity involves an acid-triggered conformational flip of 1, shortening of lipid tails, and membrane perturbations, which cause the content leakage. The methotrexate-loaded liposomes demonstrated much higher cytotoxicity in HeLa cells than the free drug indicating that they can serve as viable drug delivery systems.

Practical Dynamic Contrast Enhanced MRI in Small Animal Models of Cancer: Data Acquisition, Data Analysis, and Interpretation

September 2012

·

91 Reads

Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) consists of the continuous acquisition of images before, during, and after the injection of a contrast agent. DCE-MRI allows for noninvasive evaluation of tumor parameters related to vascular perfusion and permeability and tissue volume fractions, and is frequently employed in both preclinical and clinical investigations. However, the experimental and analytical subtleties of the technique are not frequently discussed in the literature, nor are its relationships to other commonly used quantitative imaging techniques. This review aims to provide practical information on the development, implementation, and validation of a DCE-MRI study in the context of a preclinical study (though we do frequently refer to clinical studies that are related to these topics).

Figure 1. Proposed mechanisms of transport across the blood–brain barrier. The blood brain barrier consists in essence of a polarized layer of vascular endothelial cells, tightly attached to each other by means of tight junctions, and lined up by astrocytes. A variety of transcellular transport processes can be distinguished: ( a ) Diffusion, driven by a concentration gradient, mainly involving small hydrophobic molecules. This pathway represents the main entry route into the brain of current therapeutics; ( b ) Paracellular transport–limited to small water-soluble molecules; ( c ) Carrier-mediated transport, as occurs for e.g., glucose, amino acids, nucleosides, and therapeutics such as vinca alkaloids, azidothymidine etc. ; ( d ) Receptor-mediated transcytosis for peptidic signaling and regulatory molecules (insulin, leptin, interleukins), nutrients (iron, LDL); ( e ) Adsorptive transcytosis, presumably relying on transport of positively charged cargo (serum proteins) in a non-specific manner; ( f ) Proton pump efflux transporters. 
Figure 2. Mechanisms and transport pathways in endocytosis. (a) Adaptor molecules sense the binding of a ligand to its cognate receptor and cause the formation of a clathrin cage around the plasma membrane that subsequently pinches off as internal vesicle; (b) Caveolin-1, constitutively present at the inner leaflet of the plasma membrane, forms invaginated microdomains, known as caveolae, that mediate transport of receptor-ligand complexes; (c) A non-clathrin, non-caveolae dependent mechanism is mainly responsible for the uptake of glycosylphosphatidylinositol anchored proteins.
Figure 3. Internalization and transcytosis of functionalized polymeric nanoparticles. TAT peptide and transferrin were covalently attached to polymersomes and incubated for 18 h at 37 °C with polarized filter-grown endothelial hCMEC/D3 cells, a convenient in vitro model for the BBB (see [132]). After extensive washing to remove non-bound particles, the cells were examined by fluorescence microscopy to visualize the intracellular distribution of ( a ) TAT-, Transferrin (Tf)- and non-coated polymersomes, as indicated (Scale bar: 20 μm); Alternatively ( b ), after 18 h of incubation at 37 °C the fractions of polymersomes in the apical and basolateral medium were measured and the fraction of polymersomes, transported by transcytosis across the endothelial cells, was calculated. 
Smuggling Drugs into the Brain: An Overview of Ligands Targeting Transcytosis for Drug Delivery across the Blood–Brain Barrier

December 2014

·

2,225 Reads

The blood-brain barrier acts as a physical barrier that prevents free entry of blood-derived substances, including those intended for therapeutic applications. The development of molecular Trojan horses is a promising drug targeting technology that allows for non-invasive delivery of therapeutics into the brain. This concept relies on the application of natural or genetically engineered proteins or small peptides, capable of specifically ferrying a drug-payload that is either directly coupled or encapsulated in an appropriate nanocarrier, across the blood-brain barrier via receptor-mediated transcytosis. Specifically, in this process the nanocarrier-drug system ("Trojan horse complex") is transported transcellularly across the brain endothelium, from the blood to the brain interface, essentially trailed by a native receptor. Naturally, only certain properties would favor a receptor to serve as a transporter for nanocarriers, coated with appropriate ligands. Here we briefly discuss brain microvascular endothelial receptors that have been explored until now, highlighting molecular features that govern the efficiency of nanocarrier-mediated drug delivery into the brain.

Figure 2. Representative results in the hairless mouse skin (HMS) and human epidermal membrane (HEM) studies. Isoenhancement concentrations (mM) of E = 10 obtained with HMS and HEM for the enhancers in phosphate buffered saline (PBS). Isoenhancement concentrations are defined as the aqueous concentrations for which different enhancers induce the same extent of penetration enhancement, E, for transport across the lipoidal pathway of stratum corneum. The data are taken from Chantasart et al. [30].  
Figure 3. Relationship between K SC lipid/PBS (the intercellular lipid/PBS partition coefficients) of the enhancers and K octanol/PBS (the enhancer n-octanol/PBS partition coefficients) in hairless mouse skin stratum corneum (HMS SC) and human stratum corneum (human SC). The data are taken from previous hairless mouse skin (HMS) and human epidermal membrane (HEM) studies [6,22–27,30,31]. PBS = phosphate buffered saline.  
Figure 4. Relationship between the aqueous concentrations of the enhancers to induce 10-fold penetration enhancement and enhancer K octanol/PBS (octanol/PBS partition coefficient). The data are taken from previous hairless mouse skin (HMS) and human epidermal membrane (HEM) studies [6,22–27,30,31]. PBS = phosphate buffered saline.  
Figure 5. Relationship between enhancer uptake into hairless mouse skin stratum corneum (HMS SC) and human epidermal membrane stratum corneum (HEM SC) (μmol/mg intercellular SC lipid) under the aqueous enhancer concentration to induce 10-fold penetration enhancement and enhancer K octanol/PBS (octanol/PBS partition coefficient). The data are taken from previous hairless mouse skin (HMS) and human epidermal membrane (HEM) studies [25–27,30,31]. PBS = phosphate buffered saline.  
Figure 6. Relationship between Emax (the maximum enhancement effects) and the product of K octanol/PBS (octanol/PBS partition coefficient) and Sw (aqueous solubility of enhancer) of the penetration enhancers (closed circles: enhancers, liquid at 37 °C; open circles: enhancers, solid at 37 °C). The average lipid concentration of enhancers to induce E = 10 in the symmetric studies, in which the enhancers were not at saturation, is also presented for comparison (open square). The data are taken from previous human epidermal membrane (HEM) studies [40,41].
Structure Enhancement Relationship of Chemical Penetration Enhancers in Drug Transport across the Stratum Corneum

December 2012

·

207 Reads

The stratum corneum is a major barrier of drug penetration across the skin in transdermal delivery. For effective transdermal drug delivery, skin penetration enhancers are used to overcome this barrier. In the past decades, a number of research studies were conducted to understand the mechanisms of skin penetration enhancers and to develop a structure enhancement relationship. Such understanding allows effective prediction of the effects of skin penetration enhancers, assists topical and transdermal formulation development, and avoids extensive enhancer screening in the transdermal delivery industry. In the past two decades, several hypotheses on chemical enhancer-induced penetration enhancement for transport across the skin lipoidal pathway have been examined based on a systematic approach. Particularly, a hypothesis that skin penetration enhancement is directly related to the concentration of the enhancers in the stratum corneum lipid domain was examined. A direct relationship between skin penetration enhancer potency (based on enhancer aqueous concentration in the diffusion cell chamber) and enhancer n-octanol-water partition coefficient was also established. The nature of the microenvironment of the enhancer site of action in the stratum corneum lipid domain was found to be mimicked by n-octanol. The present paper reviews the work related to these hypotheses and the relationships between skin penetration enhancement and enhancer concentration in the drug delivery media and stratum corneum lipids.

Figure 1. Ribbon diagram of human GSTP1-1 (PDB file 1PKW) [15]. In black the Tyr residue initially proposed as involved in the activation of glutathione (GSH). 
Glutathione Transferase (GST)-Activated Prodrugs

June 2013

·

254 Reads

Glutathione transferase (formerly GST) catalyzes the inactivation of various electrophile-producing anticancer agents via conjugation to the tripeptide glutathione. Moreover, several data link the overexpression of some GSTs, in particular GSTP1-1, to both natural and acquired resistance to various structurally unrelated anticancer drugs. Tumor overexpression of these proteins has provided a rationale for the search of GST inhibitors and GST activated cytotoxic prodrugs. In the present review we discuss the current structural and pharmacological knowledge of GST-activated cytotoxic compounds.

Figure 1. Chronological trend in number of SU prescription (bars) and proportion to SU prescriptions under the recommended dose (lines). (A) SU prescriptions without DPP-4 inhibitor; (B) SU prescriptions with DPP-4 inhibitor. Data is summarized for every 10 days (1st to 10th, 11th to 20th, and 21t to the end of the month for each month). The arrows indicate the timing of the recommendation release.  
Figure 2. Chronological trend in SU mean daily dose with or without same-day DPP-4 inhibitor and the other oral hypoglycemic drugs (OHD). The mean daily dose of glimepiride (A) glibenclamide; (B) gliclazide; (C) was calculated for every 10 days. Gray lines indicate the SU monotherapy, black lines indicate the SU with same-day DPP-4 inhibitor, and dotted lines indicate SU with same-day OHDs but not with DPP-4 inhibitor.  
Figure 2. Cont.  
Quantitative Evaluation of Compliance with Recommendation for Sulfonylurea Dose Co-Administered with DPP-4 Inhibitors in Japan

December 2012

·

81 Reads

After the launch of dipeptidyl peptidase-4 (DPP-4), a new oral hypoglycemic drug (OHD), in December 2009, severe hypoglycemia cases were reported in Japan. Although the definite cause was unknown, co-administration with sulfonylureas (SU) was suspected as one of the potential risk factors. The Japan Association for Diabetes Education and Care (JADEC) released a recommendation in April 2010 to lower the dose of three major SUs (glimepiride, glibenclamide, and gliclazide) when adding a DPP-4 inhibitor. To evaluate the effectiveness of this risk minimization action along with labeling changes, dispensing records for 114,263 patients prescribed OHDs between December 2008 and December 2010 were identified in the Nihon-Chouzai pharmacy claims database. The adherence to the recommended dosing of SU co-prescribed with DPP-4 inhibitors increased from 46.3% before to 63.8% after the JADEC recommendation (p < 0.01 by time-series analysis), while no change was found in those for SU monotherapy and SU with other OHD co-prescriptions. The adherence was significantly worse for those receiving a glibenclamide prescription. The JADEC recommendation, along with labeling changes, appeared to have a favorable effect on the risk minimization action in Japan. In these instances, a pharmacy claims database can be a useful tool to evaluate risk minimization actions.

Development of a New Type of Prolonged Release Hydrocodone Formulation Based on Egalet® ADPREM Technology Using In Vivo–In Vitro Correlation

December 2011

·

606 Reads

A novel abuse deterrent, prolonged release tablet formulation of Hydrocodone for once-daily dosing has been developed, based on the novel proprietary Egalet® ADPREM technology. The tablet is an injection molded polymer system consisting of an erodible matrix in which the Active Pharmaceutical Ingredient (API), such as Hydrocodone, is dispersed. The matrix is partly covered with a water-impermeable, non-erodible shell which leaves both ends of the cylindrical tablet exposed to erosion by the gastrointestinal (GI) fluid. In vivo-in vitro correlation (IVIVC) was initiated and validated with three formulations. A good internal predictability was observed for the three formulations. How the changing conditions in the GI tract influenced in vivo performance of an erosion based product was discussed. The validated IVIVC could be used to optimize the tablet formulation and to obtain a desired profile. In addition, this technique could help to establish the dissolution limits in which a certainty of bioequivalence is calculated. Based on this validated level A IVIVC, dissolution can be used as surrogate of bioequivalence for development, but also scale up post approval changes.

Effect of topically administered adriamycin on tumor growth in hairless mice. In mice treated with adriamycin cream (0.1 or 0.3 mg/day; n = 6, 5, respectively), the tumor size and weight (middle and bottom sections) were significantly smaller than those in the untreated control group (upper sections; n = 5). A higher dose of adriamycin (bottom section) slightly improved the inhibition of tumor growth. Scale bar = 1 cm.
Comparison of transdermal and subcutaneous administration of adriamycin by weight gain rate and tumor weight. The body weight gain rate (black bars, left axis) and tumor weight (striped bars, right axis) of tumor-bearing mice transdermally administered (TD) and subcutaneously injected (SC) with adriamycin were compared (n = 4). The daily transdermal administration and the once every three days subcutaneous injection of adriamycin resulted in similar anti-cancer effects, as estimated by the tumor weight. However, transdermal adriamycin administration led to a higher weight gain rate in mice than subcutaneous injection (p < 0.05, Welch’s t-test), and was statistically similar to the level in the untreated control. Data are shown as the mean ± S.D..
Distribution of transdermally administered adriamycin. Adriamycin cream was topically applied to the skin of hairless mice for three consecutive days with (A); or without (B) pretreatment with a depilatory agent. The distribution of adriamycin was then detected based on its autofluorescence. Adriamycin was observed in the dermis/fascia only after pretreatment with the depilatory agent. Scale bar = 10 µm.
Transdermal Delivery of Adriamycin to Transplanted Ehrlich Ascites Tumor in Mice

September 2013

·

73 Reads

There is considerable interest in the skin as a site of anti-cancer drug application. Nevertheless, the skin poses a formidable barrier to drug penetration, thereby limiting topical and transdermal bioavailability. However, we previously showed that a thioglycolate-based depilatory agent increases the drug permeability of mouse skin. In the present report, we investigated the skin permeability and efficacy of the anti-cancer drug adriamycin increased when administered transdermally to mice in combination with a thioglycolate-based depilatory agent. Adriamycin in combination with depilatory treatment reduced Ehrlich tumor growth in hairless mice about the weight and size of harvested tumors. In addition, our delivery method for adriamycin increased the therapeutic effectiveness of this agent by decreasing toxicity. Moreover, measurement of adriamycin autofluorescence revealed that topically applied adriamycin penetrate the dermis after depilatory agent treatment. These results indicate that the transdermal delivery of anti-cancer drugs is feasible by handy pretreatment of the skin with a thioglycolate-based depilatory agent.

Protein Adsorption Patterns and Analysis on IV Nanoemulsions—The Key Factor Determining the Organ Distribution

March 2012

·

133 Reads

Intravenous nanoemulsions have been on the market for parenteral nutrition since the 1950s; meanwhile, they have also been used successfully for IV drug delivery. To be well tolerable, the emulsions should avoid uptake by the MPS cells of the body; for drug delivery, they should be target-specific. The organ distribution is determined by the proteins adsorbing them after injection from the blood (protein adsorption pattern), typically analyzed by two-dimensional polyacrylamide gel electrophoresis, 2-D PAGE. The article reviews the 2-D PAGE method, the analytical problems to be faced and the knowledge available on how the composition of emulsions affects the protein adsorption patterns, e.g., the composition of the oil phase, stabilizer layer and drug incorporation into the interface or oil core. Data were re-evaluated and compared, and the implications for the in vivo distribution are discussed. Major results are that the interfacial composition of the stabilizer layer is the main determining factor and that this composition can be modulated by simple processes. Drug incorporation affects the pattern depending on the localization of the drug (oil core versus interface). The data situation regarding in vivo effects is very limited; mainly, it has to be referred to in the in vivo data of polymeric nanoparticles. As a conclusion, determination of the protein adsorption patterns can accelerate IV nanoemulsion formulation development regarding optimized organ distribution and related pharmacokinetics.

Correlating Physicochemical Properties of Boronic Acid-Chitosan Conjugates to Glucose Adsorption Sensitivity

March 2012

·

596 Reads

Phenyl boronic acid (PBA), which is known to interact with glucose, was covalently bonded to chitosan by direct reductive N-alkylation of chitosan with 4-formylphenylboronic acid (4-FPBA). Evidence of PBA bonding on chitosan was assessed by FTIR, ToF-SIMS, SEM, DSC and glucose adsorption sensitivity measurements. FTIR spectra showed strong signals at 1560 and 630 cm-1 indicating the formation of p-substituted benzene. Similarly, ToF-SIMS analyses on the conjugates registered fragments of boron ion (B-) at 11.0 m/z whose intensity increased in proportion to 4-FPBA loading. The degree to which PBA was bonded to chitosan was related to the 4-FPBA load used in the reaction (termed F1 through to F6 with increasing 4-FPBA load). Glucose adsorption sensitivity to PBA-bonded chitosan was directly related to the amount of PBA functionality within the conjugates and the physical nature of the matrices (porous or crystalline). Topographic analysis by SEM revealed that PBA-chitosan conjugates F1, F2 and F3 have porous matrices and their sensitivity to glucose adsorption was directly proportional to the degree of PBA substitution onto chitosan. Conversely, conjugates F4, F5 and F6 appeared crystalline under SEM and glucose adsorption sensitivity decreased in proportion to amount of PBA bonded to chitosan. The crystalline nature of the conjugates was confirmed by DSC, where the exothermic event related to the melting of the bonded PBA moiety, occurred at 338 °C. Thus, decreased sensitivity to glucose adsorption by the conjugates can be ascribed to the crystallinity imparted by increased content of the bonded PBA moiety, providing an optimal loading of PBA in terms of maximizing response to glucose.

Performance of Dry Powder Inhalers with Single Dosed Capsules in Preschool Children and Adults Using Improved Upper Airway Models

March 2014

·

399 Reads

The pulmonary administration of pharmaceutical aerosols to patients is affected by age-dependent variations in the anatomy of the upper airways and the inhalation pattern. Considering this aspect, different upper airway models, representing the geometries of adults and preschool children, and a conventional induction port according to the European Pharmacopeia were used for in vitro testing of dry powder inhalers with single dosed capsules (Cyclohaler®, Handihaler® and Spinhaler®). Deposition measurements were performed using steady flow rates of 30 and 60 L/min for the Handihaler®/Spinhaler® and 30, 60 and 75 L/min for the Cyclohaler®. The inhalation volume was set at 1 L. For the Cyclohaler®, the in vitro testing was supplemented by a pediatric inhalation profile. Slight differences of pulmonary deposition between the idealized adult (11%-15%) and pediatric (9%-11%) upper airway model were observed for the Cyclohaler®. The applied pediatric inhalation profile resulted in a reduction of pulmonary deposition by 5% compared to steady conditions and indicated the influence of the inhalation pattern on the amount of pulmonary deposited particles. The comparison of two pediatric upper airway models showed no differences. The performance of the Handihaler® was similar to the Cyclohaler®. The Spinhaler® showed an insufficient performance and limited reproducibility in our investigations.

Advances in Bio-Optical Imaging for the Diagnosis of Early Oral Cancer

December 2011

·

1,571 Reads

Oral cancer is among the most common malignancies worldwide, therefore early detection and treatment is imperative. The 5-year survival rate has remained at a dismal 50% for the past several decades. The main reason for the poor survival rate is the fact that most of the oral cancers, despite the general accessibility of the oral cavity, are not diagnosed until the advanced stage. Early detection of the oral tumors and its precursor lesions may be the most effective means to improve clinical outcome and cure most patients. One of the emerging technologies is the use of non-invasive in vivo tissue imaging to capture the molecular changes at high-resolution to improve the detection capability of early stage disease. This review will discuss the use of optical probes and highlight the role of optical imaging such as autofluorescence, fluorescence diagnosis (FD), laser confocal endomicroscopy (LCE), surface enhanced Raman spectroscopy (SERS), optical coherence tomography (OCT) and confocal reflectance microscopy (CRM) in early oral cancer detection. FD is a promising method to differentiate cancerous lesions from benign, thus helping in the determination of adequate resolution of surgical resection margin. LCE offers in vivo cellular imaging of tissue structures from surface to subsurface layers and has demonstrated the potential to be used as a minimally invasive optical biopsy technique for early diagnosis of oral cancer lesions. SERS was able to differentiate between normal and oral cancer patients based on the spectra acquired from saliva of patients. OCT has been used to visualize the detailed histological features of the oral lesions with an imaging depth down to 2-3 mm. CRM is an optical tool to noninvasively image tissue with near histological resolution. These comprehensive diagnostic modalities can also be used to define surgical margin and to provide a direct assessment of the therapeutic effectiveness.

Figure 1. Lipid nanoparticle (LNP) siRNA systems are typically composed of ionizable amino lipids, phosphatidylcholine lipids, cholesterol and polyethylene glycol-lipid conjugate (PEG-lipids). Structure of heptatriaconta-6,9,28,31-tetraen-19-yl 4-(dimethylamino)butanoate (DLin-MC3-DMA), 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), polyethylene glycol-dimyristolglycerol (PEG-DMG) and cholesterol is shown. 
Figure 2. A schematic of LNP siRNA showing a nanostructured core. 
Advances in Lipid Nanoparticles for siRNA Delivery

September 2013

·

4,996 Reads

Technological advances in both siRNA (small interfering RNA) and whole genome sequencing have demonstrated great potential in translating genetic information into siRNA-based drugs to halt the synthesis of most disease-causing proteins. Despite its powerful promises as a drug, siRNA requires a sophisticated delivery vehicle because of its rapid degradation in the circulation, inefficient accumulation in target tissues and inability to cross cell membranes to access the cytoplasm where it functions. Lipid nanoparticle (LNP) containing ionizable amino lipids is the leading delivery technology for siRNA, with five products in clinical trials and more in the pipeline. Here, we focus on the technological advances behind these potent systems for siRNA-mediated gene silencing.

Table 1. A small subset of the Multi-Level Clinical Classification Tree with International Classification of Diseases, Ninth Revision (ICD-9) codes associated with a specific level. 
Table 2. Results for terbinafine and itraconazole. 
Table 3. Results for pioglitazone and rosiglitazone. 
Table 4. Comparison of all GPS and TreeScan signals across the four drugs studied by threshold. 
Drug Adverse Event Detection in Health Plan Data Using the Gamma Poisson Shrinker and Comparison to the Tree-based Scan Statistic

March 2013

·

442 Reads

Background: Drug adverse event (AE) signal detection using the Gamma Poisson Shrinker (GPS) is commonly applied in spontaneous reporting. AE signal detection using large observational health plan databases can expand medication safety surveillance. Methods: Using data from nine health plans, we conducted a pilot study to evaluate the implementation and findings of the GPS approach for two antifungal drugs, terbinafine and itraconazole, and two diabetes drugs, pioglitazone and rosiglitazone. We evaluated 1676 diagnosis codes grouped into 183 different clinical concepts and four levels of granularity. Several signaling thresholds were assessed. GPS results were compared to findings from a companion study using the identical analytic dataset but an alternative statistical method-the tree-based scan statistic (TreeScan). Results: We identified 71 statistical signals across two signaling thresholds and two methods, including closely-related signals of overlapping diagnosis definitions. Initial review found that most signals represented known adverse drug reactions or confounding. About 31% of signals met the highest signaling threshold. Conclusions: The GPS method was successfully applied to observational health plan data in a distributed data environment as a drug safety data mining method. There was substantial concordance between the GPS and TreeScan approaches. Key method implementation decisions relate to defining exposures and outcomes and informed choice of signaling thresholds.

Figure 1. Chemical structure of ceftriaxone sodium (CAS 74578-69-1). 
Figure 2. Agar diffusion assay using a strain of B. subitilis ATCC 9371 IAL 1027 as the test microorganism. Ceftriaxone sodium reference substance is at concentrations of 15 (S1), 30 (S2), and 60 (S3) μ g/mL and the ceftriaxone sodium sample at concentrations of 15 (T1), 30 (T2), and 60 (T3) μ g/mL. 
Table 3 . Parameters assessing the robustness of the method microbiologically.
Diameters of inhibition zones obtained in the microbiological assay for evaluation the linearity of ceftriaxone sodium in pharmaceutical products-agar diffusion method.
Values obtained in the recovery test agar diffusion method for determination of ceftriaxone sodium.
Development and Validation of a Successful Microbiological Agar Assay for Determination of Ceftriaxone Sodium in Powder for Injectable Solution

December 2012

·

1,109 Reads

Ceftriaxone sodium is a cephalosporin with broad-spectrum antimicrobial activity and belongs to the third generation of cephalosporins. Regarding the quality control of medicines, a validated microbiological assay for the determination of ceftriaxone sodium in powder for injectable solution has not been reported yet. This paper reports the development and validation of a simple, accurate and reproducible agar diffusion method to quantify ceftriaxone sodium in powder for injectable solution. The assay is based on the inhibitory effect of ceftriaxone sodium on the strain of Bacillus subtilis ATCC 9371 IAL 1027 used as test microorganism. The results were treated statistically by analysis of variance and were found to be linear (r = 0.999) in the selected range of 15.0-60.0 μg/mL, precise with a relative standard deviation (RSD) of repeatability intraday = 1.40%, accurate (100.46%) and robust with a RSD lower than 1.28%. The results demonstrated the validity of the proposed bioassay, which allows reliable ceftriaxone sodium quantitation in pharmaceutical samples and therefore can be used as a useful alternative methodology for the routine quality control of this medicine.

Impact of Molecular Weight on Lymphatic Drainage of a Biopolymer-Based Imaging Agent

December 2012

·

1,606 Reads

New lymphatic imaging technologies are needed to better assess immune function and cancer progression and treatment. Lymphatic uptake depends mainly on particle size (10-100 nm) and charge. The size of carriers for imaging and drug delivery can be optimized to maximize lymphatic uptake, localize chemotherapy to lymphatic metastases, and enable visualization of treatment deposition. Toward this end, female BALB/c mice were injected subcutaneously in the hind footpad or forearm with a series of six different molecular weight hyaluronan (HA) near-infrared dye (HA-IR820) conjugates (ca. 5-200 nm). Mice were imaged using whole body fluorescent imaging over two weeks. HA-IR820 fluorescence was clearly visualized in the draining lymphatic capillaries, and in the popliteal and iliac or axillary lymph nodes. The 74-kDa HA-IR820 had the largest lymph node area-under-the-curve. In contrast to prior reports, mice bearing limb tumors exhibited three-fold longer retention of 74-kDa HA-IR820 in the popliteal node compared to mice without tumors. HA conjugate kinetics and disposition can be specifically tailored by altering their molecular weight. The specific lymphatic uptake and increased nodal retention of HA conjugates indicate significant potential for development as a natural biopolymer for intralymphatic drug delivery and imaging.

Figure 1. Structures of trimetallic nitride endohedral metallofullerene and empty cage fullerene C 70 . 
Table 1 . Summary of biomedical applications of fullerenes.
Figure 2. Three types of fullerene liposomes incorporating un-derivatized fullerenes, lipophilic fullerenes and amphiphilic fullerenes, respectively. 
Figure 3. Vesicle formation of amphiphilic fullerene compound ALM with auxiliary phospholipids. 
Figure 4. Fullerenes attenuate inflammatory arthritis of the K/BxN-induced disease pathology. ( A ) Serum-treated mice demonstrated typical synovial hyperplasia, pannus formation and inflammatory infiltrates; ( B ) By contrast, ALM-treated animals had less evidence of clinical joint inflammation compared with ( C ) non-diseased animals. ALM: Amphiphilic liposomal malonylfullerene. 
Liposome Formulation of Fullerene-Based Molecular Diagnostic and Therapeutic Agents

December 2013

·

1,302 Reads

Fullerene medicine is a new but rapidly growing research subject. Fullerene has a number of desired structural, physical and chemical properties to be adapted for biological use including antioxidants, anti-aging, anti-inflammation, photodynamic therapy, drug delivery, and magnetic resonance imaging contrast agents. Chemical functionalization of fullerenes has led to several interesting compounds with very promising preclinical efficacy, pharmacokinetic and safety data. However, there is no clinical evaluation or human use except in fullerene-based cosmetic products for human skincare. This article summarizes recent advances in liposome formulation of fullerenes for the use in therapeutics and molecular imaging.

Figure 1. Structures of cholesteryl-3β-carboxyamidoethylene-N-hydroxyethylamine, OH-Chol and commercially available cationic cholesterol DC-Chol (lower). 
Figure 2. A structure of biosurfactant MEL-A which consists of 4-O-[β-D-mannopyranosyl] meso-erythritol], esterified two fatty acids and two acetic acids. 
Figure 4. CLSM images of NIH3T3 cells incubated with fluorescence labeled liposome-DNA complex. NIH3T3 cells were incubated with FITC-conjugated oligonucleotides complexed with rhodamine-labeled liposomes composed of OH-Chol without MEL-A (a) and with MEL-A (b) for 1 h. Fluorescence images of liposome (right) and merged images on a transmittance image with pseudo-color (yellow for DNA, blue for liposome, and pink for liposome-DNA-complex) (left) are shown. 
Figure 6. (Upper) Intracellular localization of FAM-labeled siRNA with MEL-A-containing cationic liposomes. Lysotracker Red stained B16/BL6 cells were observed 0.5 h after incubation with liposome/siRNA. Left is DIC and Right is a CLSM image of FAM-labeled siRNA; (Lower) Time-depended silence effects for the experiments with MEL-A-containing cationic liposomes (blue) and Lipofectamine™ RNAiMax (red). 
New Transfection Agents Based on Liposomes Containing Biosurfactant MEL-A

September 2013

·

150 Reads

Nano vectors are useful tools to deliver foreign DNAs, oligonucleotides, and small interfering double-stranded RNAs (siRNAs) into mammalian cells with gene transfection and gene regulation. In such experiments we have found the liposomes with a biosurfacant mannosylerythriol lipid (MEL-A) are useful because of their high transfer efficiency, and their unique mechanism to transfer genes to target cells with the lowest toxicity. In the present review we will describe our current work, which may contribute to the great advance of gene transfer to target cells and gene regulations. For more than two decades, the liposome technologies have changed dramatically and various methods have been proposed in the fields of biochemistry, cell biology, biotechnology, and so on. In addition, they were towards to pharmaceutics and clinical applications. The liposome technologies were expected to use gene therapy, however, they have not reached a requested goal as of yet. In the present paper we would like to present an approach using a biosurfactant, MEL-A, which is a surface-active compound produced by microorganisms growing on water-insoluble substrates and increases efficiency in gene transfection. The present work shows new transfection agents based on liposomes containing biosurfactant MEL-A.

Figure 1. Chemical structures of some polyphenols mentioned in this review.  
Table 1 . Examples of liposomal forms developed for polyphenol biological studies.
Table 1 . Cont.
Figure 2. Biological interest of formulating polyphenol into liposomes. The histograms are based on the references indicated in the figure. Area under the curve (AUC) for the free polyphenol was fixed at level 1; the level given for the liposomal form of polyphenol corresponds to the AUC increase factor as compared to the free polyphenol (A) for orally administered liposomes; (B) for intravenously administered liposomes (cf. [24,25,50,54,62,63]).  
Bioavailability of Polyphenol Liposomes: A Challenge Ahead

September 2013

·

516 Reads

Dietary polyphenols, including flavonoids, have long been recognized as a source of important molecules involved in the prevention of several diseases, including cancer. However, because of their poor bioavailability, polyphenols remain difficult to be employed clinically. Over the past few years, a renewed interest has been devoted to the use of liposomes as carriers aimed at increasing the bioavailability and, hence, the therapeutic benefits of polyphenols. In this paper, we review the causes of the poor bioavailability of polyphenols and concentrate on their liposomal formulations, which offer a means of improving their pharmacokinetics and pharmacodynamics. The problems linked to their development and their potential therapeutic advantages are reviewed. Future directions for liposomal polyphenol development are suggested.

Figure 3. Crystallized particles of mannitol at the outlet air temperature at (a) 40 °C and (b) 66 °C. 
Figure 3 shows the formation of particles containing needle-shaped crystals of mannitol observed by SEM.
Figure 4. External structures of spray-dried powders. Inlet air temperature, 120 °C; atomizer speed, 20,000 rpm; (a,b), mannitol; (c,d), the equal-mass mixture of mannitol and MD. (a) and (c) are 450 times magnification; (b) and (d) are 1000 times magnification. 
Figure 5. Powder X-ray diffractograms of spray-dried powders. Red line: mannitol; and blue line: the equal-mass mixture of mannitol and MD. 
Encapsulation of Alcohol Dehydrogenase in Mannitol by Spray Drying

March 2014

·

339 Reads

The retention of the enzyme activity of alcohol dehydrogenase (ADH) has been studied in various drying processes such as spray drying. The aim of this study is to encapsulate ADH in mannitol, either with or without additive in order to limit the thermal denaturation of the enzyme during the drying process. The retention of ADH activity was investigated at different drying temperatures. When mannitol was used, the encapsulated ADH was found inactive in all the dried powders. This is presumably due to the quick crystallization of mannitol during spray drying that resulted in the impairment of enzyme protection ability in comparison to its amorphous form. Maltodextin (dextrose equivalent = 11) was used to reduce the crystallization of mannitol. The addition of maltodextrin increased ADH activity and drastically changed the powder X-ray diffractogram of the spray-dried powders.

Self-Assembled Lipoplexes of Short Interfering RNA (siRNA) Using Spermine-Based Fatty Acid Amide Guanidines: Effect on Gene Silencing Efficiency

December 2011

·

468 Reads

Four guanidine derivatives of N4,N9-diacylated spermine have been designed, synthesized, and characterized. These guanidine-containing cationic lipids bound siRNA and formed nanoparticles. Two cationic lipids with C18 unsaturated chains, N1,N12-diamidino-N4,N9-dioleoylspermine and N1,N12-diamidino-N4-linoleoyl-N9-oleoylspermine, were more efficient in terms of GFP expression reduction compared to the other cationic lipids with shorter C12 (12:0) and very long C22 (22:1) chains. N1,N12-Diamidino-N4-linoleoyl-N9-oleoylspermine siRNA lipoplexes resulted in GFP reduction (26%) in the presence of serum, and cell viability (64%). These data are comparable to those obtained with TransIT TKO. Thus, cationic lipid guanidines based on N4,N9-diacylated spermines are good candidates for non-viral delivery of siRNA to HeLa cells using self-assembled lipoplexes.

Efficient Gene Silencing by Self-Assembled Complexes of siRNA and Symmetrical Fatty Acid Amides of Spermine

December 2011

·

519 Reads

Gene silencing by siRNA (synthetic dsRNA of 21-25 nucleotides) is a well established biological tool in gene expression studies and has a promising therapeutic potential for difficult-to-treat diseases. Five fatty acids of various chain length and oxidation state (C12:0, C18:0, C18:1, C18:2, C22:1) were conjugated to the naturally occurring polyamine, spermine, and evaluated for siRNA delivery and gene knock-down. siRNA delivery could not be related directly to gene silencing efficiency as N4,N9-dierucoyl spermine resulted in higher siRNA delivery compared to N4,N9-dioleoyl spermine. GFP silencing in HeLa cells showed that the unsaturated fatty acid amides are more efficient than saturated fatty acid amides, with N4,N9-dioleoyl spermine resulting in the most efficient gene silencing in the presence of serum. The alamarBlue cell viability assay showed that fatty acid amides of spermine have good viability (75%-85% compared to control) except N4,N9-dilauroyl spermine which resulted in low cell viability. These results prove that unsaturated fatty acid amides of spermine are efficient, non-toxic, non-viral vectors for siRNA mediated gene silencing.

Figure 5. PCA score plot of Raman data (900 cm −1 to 1800 cm −1 ). Milled samples (M1, M2 and M3), quench cooled samples (Q1, Q2 and Q3), crystalline anhydrate (AH) and crystalline dihydrate (DH).  
Figure 8. PCA score plot of PDF data (4 Å to 40 Å) using the 5° to 40° 2θ XRPD diffraction range. Milled samples (M1, M2 and M3), quench cooled samples (Q1, Q2 and Q3), crystalline anhydrate (AH) and crystalline dihydrate (DH).
Atomic Pairwise Distribution Function Analysis of the Amorphous Phase Prepared by Different Manufacturing Routes

December 2012

·

147 Reads

Amlodipine besilate, a calcium channel antagonist, exists in several solid forms. Processing of anhydrate and dihydrate forms of this drug may lead to solid state changes, and is therefore the focus of this study. Milling was performed for the anhydrate form, whereas the dihydrate form was subjected to quench cooling thereby creating an amorphous form of the drug from both starting materials. The milled and quench cooled samples were, together with the crystalline starting materials, analyzed with X-ray powder diffraction (XRPD), Raman spectroscopy and atomic pair-wise distribution function (PDF) analysis of the XRPD pattern. When compared to XRPD and Raman spectroscopy, the PDF analysis was superior in displaying the difference between the amorphous samples prepared by milling and quench cooling approaches of the two starting materials.

Figure 1. Analytical transmission electron microscopy (ATEM) characterisation of the model macroemulsion ( A as well as C , D and E ) and nanoemulsion ( B ) with incorporated titanium dioxide particles by energy-filtered transmission electron microscopy (EFTEM), energy-dispersive X-ray spectroscopy (EDXS) and electron energy loss spectroscopy (EELS) analyses without prior staining. Images ( A ) and ( B ) show zero-loss filtered bright field TEM images of the macroemulsion ( A ) and the nanoemulsion ( B ) (scale bars represent 500 nm). Image ( C ) shows a representative multicoloured energy-filtered image of superimposed titanium (Ti L) and oxygen (O K) maps, i.e. , the elemental distribution, obtained from the macroemulsion sample. Titanium is marked in green while oxygen is marked in red. Image ( D ) shows an EDXS spectrum of the macroemulsion. Image ( E ) represents an EELS spectrum obtained from a titanium dioxide aggregate within the macroemulsion. 
Figure 2. EELS spectra of bulk plasmon energy region obtained from the original macroemulsion (A) and titanium dioxide-carbon reference samples (B, C); The green lines show correlation between Ti low loss peaks which are present in both: low loss regions of macroemulsion and the reference spectra; red line indicates carbon low loss peak; (D) zero-loss filtered bright field TEM images of titanium dioxide-carbon reference sample. Selected areas indicate positions where EELS spectra for Ref. 1 and Ref. 2 were taken.
Figure 3. Characterization of the model macroemulsion with incorporated titanium dioxide particles by conventional zero-loss filtered bright field TEM ( A ) and EFTEM ( B ); The RGB EFTEM image shows the superimposed elemental maps of carbon (blue), titanium (red) and oxygen (green); ( C ) High resolution bright field TEM image of titanium dioxide particles. The scale bar represents 50 nm in ( A , B ) and 5 nm in ( C ). 
Figure 4. Conventional two-dimensional TEM projection images of the model nanoemulsion and macroemulsion with incorporated titanium dioxide particles and corresponding surface profiles as mathematically extracted from the EFTEM data. Both samples were negatively stained with a 2% aqueous uranyl acetate solution. Images (A) and (B) show zero-loss filtered bight field TEM images of the nanoemulsion (A) and the macroemulsion (B). The images below show the corresponding surface profile for the nanoemulsion (C) and for the macroemulsion (D) Black arrows indicate a hollow droplet shells composed of dried surfactant film. Scale bars represent 500 nm.
Figure 5. ATEM characterization of a commercially available liquid formulation containing unspecified nanomaterial by EFTEM, EDXS and EELS analyses without prior staining. Image (A) shows a zero-loss filtered bright field image of the formulation (scale bar represents 500 nm). In image (B), a multicolored EFTEM image of the elemental distribution within the formulation is given. The elemental distribution of silicon (blue) and oxygen (red) is documented in different colors. Images (C) and (D) show EDXS spectra of the same formulation with two different energy scales. In image (E), an EELS spectrum of the silicon (Si L) and carbon (C K) ionization edges are given.
Analytical Electron Microscopy for Characterization of Fluid or Semi-Solid Multiphase Systems Containing Nanoparticulate Material

March 2013

·

461 Reads

The analysis of nanomaterials in pharmaceutical or cosmetic preparations is an important aspect both in formulation development and quality control of marketed products. Despite the increased popularity of nanoparticulate compounds especially in dermal preparations such as emulsions, methods and protocols of analysis for the characterization of such systems are scarce. This work combines an original sample preparation procedure along with different methods of analytical electron microscopy for the comprehensive analysis of fluid or semi-solid dermal preparations containing nanoparticulate material. Energy-filtered transmission electron microscopy, energy-dispersive X-ray spectroscopy, electron energy loss spectroscopy and high resolution imaging were performed on model emulsions and a marketed product to reveal different structural aspects of both the emulsion bulk phase and incorporated nanosized material. An innovative analytical approach for the determination of the physical stability of the emulsion under investigation is presented. Advantages and limitations of the employed analytical imaging techniques are highlighted.

First Quantitative Imaging of Organic Fluorine within Angiogenic Tissues by Particle Induced Gamma-Ray Emission (PIGE) Analysis: First PIGE Organic Fluorine Imaging

December 2011

·

148 Reads

PET (Positron Emission Tomography) allows imaging of the in vivo distribution of biochemical compounds labeled with a radioactive tracer, mainly 18F-FDG (2-deoxy-2-[18F] fluoro-D-glucose). 18F only allows a relatively poor spatial resolution (2-3 mm) which does not allow imaging of small tumors or specific small size tissues, e.g. vasculature. Unfortunately, angiogenesis is a key process in various physiologic and pathologic processes and is, for instance, involved in modern anticancer approaches. Thus ability to visualize angiogenesis could allow early diagnosis and help to monitor the response of cancer to specific chemotherapies. Therefore, indirect analytical techniques are required to assess the localization of fluorinated compounds at a micrometric scale. Multimodality imaging approaches could provide accurate information on the metabolic activity of the target tissue. In this article, PIGE method (Particle Induced Gamma-ray Emission) was used to determine fluorinated tracers by the nuclear reaction of 19F(p,p′γ)19F in tissues. The feasibility of this approach was assessed on polyfluorinated model glucose compounds and novel peptide-based tracer designed for angiogenesis imaging. Our results describe the first mapping of the biodistribution of fluorinated compounds in both vascularized normal tissue and tumor tissue.

Effect of Microencapsulation Shear Stress on the Structural Integrity and Biological Activity of a Model Monoclonal Antibody, Trastuzumab

December 2011

·

2,656 Reads

The aim of the present study was to investigate the influence of process shear stressors on the stability of a model monoclonal antibody, trastuzumab. Trastuzumab, at concentrations of 0.4-4.0 mg/mL, was subjected to sonication, freeze-thaw, lyophilisation, spray drying and was encapsulated into micro- and nanoparticles. The stressed samples were analysed for structural integrity by gel electrophoresis, SDS-PAGE, and size exclusion chromatography (SEC), while the conformational integrity was analysed by circular dichroism (CD). Biological activity of the stressed trastuzumab was investigated by measuring the inhibition of cell proliferation of HER-2 expressing cell lines. Results show that trastuzumab was resistant to the process shear stresses applied and to microencapsulation processes. At the lowest concentration of 0.4 mg/mL, a low percent ( 0.05). The results of this study conclude that trastuzumab may be resistant to various processing stresses. These findings have important implications with respect to pharmaceutical processing of monoclonal antibodies.

Table 1 . Characteristics of selected oral antidiabetic drugs. 
Table 1 . Cont. 
Figure 1. Uptake and export transporters involved in the intestinal absorption (enterocyte) and the hepatic (hepatocyte) and renal (renal epithelium) excretion of oral antidiabetic drugs. Uptake transporters (red): OATP = members of the organic anion transporting polypeptide family; OCT = members of the organic cation transporters; export transporters (blue): MRP2 = multidrug resistance protein 2; BSEP = bile salt export pump; BCRP = breast cancer resistance protein; P-gp = P-glycoprotein; MATE = members of the multidrug and toxin extrusion protein family. 
Figure 3. Inhibition of OATP1B1-(top) and OATP1B3-mediated (bottom) pravastatin uptake (50 µM) by the oral antidiabetic drugs repaglinide (Repa) and rosiglitazone (Rosi). Data are shown as the percentage of OATP1B1-or OATP1B3-mediated pravastatin uptake in the absence of the respective drug (without). *P < 0.05; **P < 0.01 vs. control. (modified from [64]). 
Transporter-Mediated Drug–Drug Interactions with Oral Antidiabetic Drugs

December 2011

·

1,432 Reads

Uptake transporters (e.g., members of the SLC superfamily of solute carriers) and export proteins (e.g., members of the ABC transporter superfamily) are important determinants for the pharmacokinetics of drugs. Alterations of drug transport due to concomitantly administered drugs that interfere with drug transport may alter the kinetics of drug substrates. In vitro and in vivo studies indicate that many drugs used for the treatment of metabolic disorders and cardiovascular diseases (e.g., oral antidiabetic drugs, statins) are substrates for uptake transporters and export proteins expressed in the intestine, the liver and the kidney. Since most patients with type 2 diabetes receive more than one drug, transporter-mediated drug-drug interactions are important molecular mechanisms leading to alterations in oral antidiabetic drug pharmacokinetics with the risk of adverse drug reactions. This review focuses on uptake transporters of the SLCO/SLC21 (OATP) and SLC22 (OCT/OAT) family of solute carriers and export pumps of the ABC (ATP-binding cassette) transporter superfamily (especially P-glycoprotein) as well as the export proteins of the SLC47 (MATE) family and their role for transporter-mediated drug-drug interactions with oral antidiabetic drugs.

Figure 1. Scope of the review and summary of the experimental section. The gray area symbolizes the focus of this review, i.e. , pharmacokinetic (PK) drug interactions of antimicrobial drugs. Arrows symbolize a PK interaction. Upwards pointing arrows (↑): interaction affecting antimicrobial drug (§3.x.1 “Antimicrobial drugs as victims” ). Downwards pointing arrows ( ↓ ): interaction affecting co-prescribed drug (§3.x.2 “Antimicrobial drugs as perpetrators” ). 
Table 1 . Summary of interactions of the oxazolidinone LZD with enzyme systems and/or food.
Table 3 . Summary of interactions of macrolides with enzyme systems and/or food.
Summary of interactions of rifamycines with enzyme systems and/or food.
Pharmacokinetic Drug Interactions of Antimicrobial Drugs: A Systematic Review on Oxazolidinones, Rifamycines, Macrolides, Fluoroquinolones, and Beta-Lactams

December 2011

·

404 Reads

Like any other drug, antimicrobial drugs are prone to pharmacokinetic drug interactions. These drug interactions are a major concern in clinical practice as they may have an effect on efficacy and toxicity. This article provides an overview of all published pharmacokinetic studies on drug interactions of the commonly prescribed antimicrobial drugs oxazolidinones, rifamycines, macrolides, fluoroquinolones, and beta-lactams, focusing on systematic research. We describe drug-food and drug-drug interaction studies in humans, affecting antimicrobial drugs as well as concomitantly administered drugs. Since knowledge about mechanisms is of paramount importance for adequate management of drug interactions, the most plausible underlying mechanism of the drug interaction is provided when available. This overview can be used in daily practice to support the management of pharmacokinetic drug interactions of antimicrobial drugs.

Figure 1. Effect of combretastatin A-4 phosphate (CA4P) (25 mg/kg) [117], NPI (7.5 mg/kg) [132], and combretastatin A-1 Phosphate (OXi4503) (50 mg/kg) (unpublished data) in 200 mm 3 C3H mammary carcinomas as measured by initial area under the curve (IAUC) (90 s) (red) and K trans from Toft's model (blue) 3 h following treatment. Bars show mean of tumour median values ± SE.  
Table 1 . Angiogenesis inhibitors.
Table 1 . Cont.
Table 2 . Vascular disrupting agents.
Dynamic Contrast-Enhanced Magnetic Resonance Imaging (DCE-MRI) in Preclinical Studies of Antivascular Treatments

December 2012

·

157 Reads

Antivascular treatments can either be antiangiogenic or targeting established tumour vasculature. These treatments affect the tumour microvasculature and microenvironment but may not change clinical measures like tumour volume and growth. In research on antivascular treatments, information on the tumour vasculature is therefore essential. Preclinical research is often used for optimization of antivascular drugs alone or in combined treatments. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is an in vivo imaging method providing vascular information, which has become an important tool in both preclinical and clinical research. This review discusses common DCE-MRI imaging protocols and analysis methods and provides an overview of preclinical research on antivascular treatments utilizing DCE-MRI.

Figure 1. Current therapeutic targets for TNBC treatment. 
Figure 2. Diagram of PI3K/Akt and Ras/Raf pathway (see text for details). 
The Potential Role of Nanotechnology in Therapeutic Approaches for Triple Negative Breast Cancer

June 2013

·

159 Reads

Triple Negative Breast Cancer, TNBC, a highly aggressive and metastatic type of breast cancer, is characterized by loss of expression of the estrogen receptor (ER), progesterone receptor (PR), and a lack of overexpression of the human epidermal growth factor receptor 2 (HER2). It is a heterogeneous group of tumors with diverse histology, molecular uniqueness and response to treatment. Unfortunately, TNBC patients do not benefit from current anti-HER2 or hormone positive targeted breast cancer treatments; consequently, these patients rely primarily on chemotherapy. However, the 5-year survival rate for woman with metastatic TNBC is less than 30%. As a result of ineffective treatments, TNBC tumors often progress to metastatic lesions in the brain and lung. Brain metastases of invasive breast cancer are associated with 1 and 2 year survival rate of 20% and <2% respectively. Because the only current systemic treatment for TNBC is chemotherapy, alternative targeted therapies are urgently needed to improve the prognosis for TNBC patients. This review is focused on opportunities for developing new approaches for filling the current void in an effective treatment for TNBC patients.

Artificial Neural Networks in Evaluation and Optimization of Modified Release Solid Dosage Forms

December 2012

·

2,531 Reads

Implementation of the Quality by Design (QbD) approach in pharmaceutical development has compelled researchers in the pharmaceutical industry to employ Design of Experiments (DoE) as a statistical tool, in product development. Among all DoE techniques, response surface methodology (RSM) is the one most frequently used. Progress of computer science has had an impact on pharmaceutical development as well. Simultaneous with the implementation of statistical methods, machine learning tools took an important place in drug formulation. Twenty years ago, the first papers describing application of artificial neural networks in optimization of modified release products appeared. Since then, a lot of work has been done towards implementation of new techniques, especially Artificial Neural Networks (ANN) in modeling of production, drug release and drug stability of modified release solid dosage forms. The aim of this paper is to review artificial neural networks in evaluation and optimization of modified release solid dosage forms.

Cell Migration and Invasion Assays as Tools for Drug Discovery

December 2011

·

2,605 Reads

Cell migration and invasion are processes that offer rich targets for intervention in key physiologic and pathologic phenomena such as wound healing and cancer metastasis. With the advent of high-throughput and high content imaging systems, there has been a movement towards the use of physiologically relevant cell-based assays earlier in the testing paradigm. This allows more effective identification of lead compounds and recognition of undesirable effects sooner in the drug discovery screening process. This article will review the effective use of several principle formats for studying cell motility: scratch assays, transmembrane assays, microfluidic devices and cell exclusion zone assays.

Figure 1. Calcein assay. Concentration-dependent effect of dovitinib on baseline calcein fluorescence in L-MDR1 cells and lack of effect in the corresponding parental cell line LLC-PK1 indicating P-gp inhibition by dovitinib. Each curve depicts one representative experiment of a series of 3. Data are expressed as mean ± SEM for n = 8 wells. 
Table 1 . IC50 and f2 (concentration needed to increase baseline fluorescence two-fold) values for transporter inhibition assays for dovitinib and the corresponding control compound. 
Figure 2. Induction assay. Concentration-dependent effect of dovitinib (0.1-5 µM) and 20 µM rifampicin (positive control) after four days on mRNA expression in LS180 cells compared to untreated medium control. Expression data were normalised to the housekeeping gene G6PDH. Data are expressed as mean ± SEM for n = 8 (four biological replicates and two PCR runs for every sample) and normalised to medium control (set to 1). The differences in mRNA expression following incubation with the compounds investigated compared with the respective vehicle control were tested using ANOVA with Dunnett's post hoc test. * p < 0.05, ** p < 0.01. 
Figure 5. Reporter gene assay. Concentration-dependent effect of dovitinib (0.005-5 µM) and TCDD (0.01-50 nM; insert) on AhR activity in AZ-AhR cells. Each curve depicts the results of three experiments with each concentration tested in triplicate. Data are expressed as mean ± SEM for n = 9. 
Figure 6. Growth inhibition assay. Concentration-dependent effect of dovitinib (0.1-100 µM) on the proliferation of the P-gp over-expressing cell line MDCKII-MDR1, the BCRP over-expression cell line MDCKII-BCRP, and the control cell line MDCKII parental. Each curve depicts the results of four experiments with each concentration tested in octuplet. Data are expressed as mean ± SEM for n = 32 wells. 
Interaction Potential of the Multitargeted Receptor Tyrosine Kinase Inhibitor Dovitinib with Drug Transporters and Drug Metabolising Enzymes Assessed in Vitro

December 2014

·

124 Reads

Dovitinib (TKI-258) is under development for the treatment of diverse cancer entities. No published information on its pharmacokinetic drug interaction potential is available. Thus, we assessed its interaction with important drug metabolising enzymes and drug transporters and its efficacy in multidrug resistant cells in vitro. P-glycoprotein (P-gp, MDR1, ABCB1) inhibition was evaluated by calcein assay, inhibition of breast cancer resistance protein (BCRP, ABCG2) by pheophorbide A efflux, and inhibition of organic anion transporting polypeptides (OATPs) by 8-fluorescein-cAMP uptake. Inhibition of cytochrome P450 3A4, 2C19, and 2D6 was assessed by using commercial kits. Induction of transporters and enzymes was quantified by real-time RT-PCR. Possible aryl hydrocarbon receptor (AhR) activating properties were assessed by a reporter gene assay. Substrate characteristics were evaluated by growth inhibition assays in cells over-expressing P-gp or BCRP. Dovitinib weakly inhibited CYP2C19, CYP3A4, P-gp and OATPs. The strongest inhibition was observed for BCRP (IC50 = 10.3 ± 4.5 μM). Among the genes investigated, dovitinib only induced mRNA expression of CYP1A1, CYP1A2, ABCC3 (coding for multidrug resistance-associated protein 3), and ABCG2 and suppressed mRNA expression of some transporters and drug metabolising enzymes. AhR reporter gene assay demonstrated that dovitinib is an activator of this nuclear receptor. Dovitinib retained its efficacy in cell lines over-expressing P-gp or BCRP. Our analysis indicates that dovitinib will most likely retain its efficacy in tumours over-expressing P-gp or BCRP and gives first evidence that dovitinib might act as a perpetrator drug in pharmacokinetic drug-drug interactions.

Effects of Chemical and Physical Enhancement Techniques on Transdermal Delivery of Cyanocobalamin (Vitamin B12) In Vitro

December 2011

·

758 Reads

Vitamin B12 deficiency, which may result in anemia and nerve damage if left untreated, is currently treated by administration of cyanocobalamin via oral or intramuscular routes. However, these routes are associated with absorption and compliance issues which have prompted us to investigate skin as an alternative site of administration. Delivery through skin, however, is restricted to small and moderately lipophilic molecules due to the outermost barrier, the stratum corneum (SC). In this study, we have investigated the effect of different enhancement techniques, chemical enhancers (ethanol, oleic acid, propylene glycol), iontophoresis (anodal iontophoresis) and microneedles (soluble maltose microneedles), which may overcome this barrier and improve cyanocobalamin delivery. Studies with different chemical enhancer formulations indicated that ethanol and oleic acid decreased the lag time while propylene glycol based formulations increased the lag time. The formulation with ethanol (50%), oleic acid (10%) and propylene glycol (40%) showed the maximum improvement in delivery. Iontophoresis and microneedle treatments resulted in enhanced permeation levels compared to passive controls. These enhancement approaches can be explored further to develop alternative treatment regimens.

Table 1. Comparison of microemulsions with emulsions and nanoemulsions. 
Table 2. Cont. 
Table 2 . Examples of microemulsion composition and incorporated drugs used as transdermal delivery systems.
Overcoming the Cutaneous Barrier with Microemulsions

March 2014

·

2,131 Reads

Microemulsions are fluid and isotropic formulations that have been widely studied as delivery systems for a variety of routes, including the skin. In spite of what the name suggests, microemulsions are nanocarriers, and their use as topical delivery systems derives from their multiple advantages compared to other dermatological formulations, such as ease of preparation, thermodynamic stability and penetration-enhancing properties. Composition, charge and internal structure have been reported as determinant factors for the modulation of drug release and cutaneous and transdermal transport. This manuscript aims at reviewing how these and other characteristics affect delivery and make microemulsions appealing for topical and transdermal administration, as well as how they can be modulated during the formulation design to improve the potential and efficacy of the final system.

Oral Liquid Formulation of Levothyroxine Is Stable in Breakfast Beverages and May Improve Thyroid Patient Compliance

December 2013

·

1,276 Reads

Patients on treatment with levothyroxine (T4) are informed to take this drug in the morning, at least 30 min before having breakfast. A significant decrease of T4 absorption was reported, in fact, when T4 solid formulations are taken with food or coffee. According to preliminary clinical study reports, administration of T4 oral solution appears to be less sensitive to the effect of breakfast beverages on oral bioavailability. In the present study, stability of T4 oral solution added to breakfast beverages was investigated. A 1 mL ampoule of single-dose Tirosint® oral solution (IBSA Farmaceutici Italia, Lodi, Italy) was poured into defined volumes of milk, tea, coffee, and coffee with milk warmed at 50 °C, as well as in orange juice at room temperature. Samples were sequentially collected up to 20 min and analyzed by validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods. The results of the study demonstrated that T4 is stable in all beverages after 20 min incubation. Demonstration of T4 stability is a prerequisite for a thorough evaluation of the effect of breakfast beverages on the bioavailability of T4 given as oral solution and for a better understanding of the reasons underlying a decreased T4 bioavailability administered as solid formulations.

Structural Versatility of Bicellar Systems and Their Possibilities as Colloidal Carriers

December 2011

·

757 Reads

Bicellar systems are lipid nanostructures formed by long- and short-chained phospholipids dispersed in aqueous solution. The morphological transitions of bicellar aggregates due to temperature, composition and time variations have been revised in this work. To this end, two bicellar systems have been considered; one formed by dimyristoyl-phosphatidylcholine (DMPC) and dihexanoyl- phosphatidylcholine (DHPC) and another formed by dipalmitoyl-phosphatidylcholine (DPPC) and DHPC. The relationship between the magnetic alignment, the morphology of the aggregates and the phase transition temperature (Tm) of lipids is discussed. In general terms, the non-alignable samples present rounded objects at temperature below the Tm. Above this temperature, an increase of viscosity is followed by the formation of large elongated aggregates. Alignable samples presented discoidal objects below the Tm. The best alignment was achieved above this temperature with large areas of lamellar stacked bilayers and some multilamellar vesicles. The effect of the inclusion of ceramides with different chain lengths in the structure of bicelles is also revised in the present article. A number of physical techniques show that the bicellar structures are affected by both the concentration and the type of ceramide. Systems are able to incorporate 10% mol of ceramides that probably are organized forming domains. The addition of 20% mol of ceramides promotes destabilization of bicelles, promoting the formation of mixed systems that include large structures. Bicellar systems have demonstrated to be morphologically stable with time, able to encapsulate different actives and to induce specific effects on the skin. These facts make bicellar systems good candidates as colloidal carriers for dermal delivery. However, water dilution induces structural changes and formation of vesicular structures in the systems; stabilization strategies have been been explored in recent works and are also updated here.

Photographs of (a) free yeast cells, (b) blank gellan gum microspheres, (c) encapsulated yeast cells in gellan gum microspheres and re-used yeast-gellan gum micro-bioreactors after the (d) first, (e) second and (f) tenth fermentation cycles.
Fermentation efficiency of free yeast cells (■) and yeast-gellan gum micro-bioreactors in the first (●) and second (○) fermentation cycles.
Viable count of free cells (bar) and fermentation efficiency (line) of two batches (

, ●) and three batches (□, ○) of yeast-gellan gum micro-bioreactors
Fermentation efficiency of free yeast cells and re-used yeast-gellan gum micro-bioreactors.
Viable counts of free yeast cells in the fermentation media and their corresponding ethanol yields.
Development of Re-Usable Yeast-Gellan Gum Micro-Bioreactors for Potential Application in Continuous Fermentation to Produce Bio-Ethanol

December 2011

·

206 Reads

The objectives of this study were to investigate the feasibility of encapsulating yeast cells using gellan gum by an emulsification method and to evaluate the fermentation efficiency and the reusability of the micro-bioreactors produced. It was found that yeast cells could be successfully encapsulated to form relatively spherical micro-bioreactors with high specific surface area for mass transfer. Cell viability was found to be reduced by one log reduction after the emulsification process. The ethanol yield of the micro-bioreactors was comparable to that of free yeast in the first fermentation cycle. The micro-bioreactors remained intact and could be re-used up to 10 cycles of fermentation. Despite cell breakthrough, relatively high ethanol yields were obtained, indicating that the micro-bioreactors also functioned as regenerative reservoirs of yeast.

Bioavailability of a Lipidic Formulation of Curcumin in Healthy Human Volunteers

December 2012

·

547 Reads

Numerous publications have reported the significant pharmacodynamic activity of Curcumin (CRM) despite low or undetectable levels in plasma. The objective of the present study was to perform a detailed pharmacokinetic evaluation of CRM after the oral administration of a highly bioavailable lipidic formulation of CRM (CRM-LF) in human subjects. Cmax, Tmax and AUC0-¥ were found to be 183.35 ± 37.54 ng/mL, 0.60 ± 0.05 h and 321.12 ± 25.55 ng/mL respectively, at a dose of 750 mg. The plasma profile clearly showed three distinct phases, viz., absorption, distribution and elimination. A close evaluation of the primary pharmacokinetic parameters provided valuable insight into the behavior of the CRM after absorption by CRM-LF. CRM-LF showed a lag time (Tlag) of 0.18 h (around 12 min). Pharmacokinetic modeling revealed that CRM-LF followed a two-compartment model with first order absorption, lag time and first order elimination. A high absorption rate constant (K01, 4.51/h) signifies that CRM-LF ensured rapid absorption of the CRM into the central compartment. This was followed by the distribution of CRM from the central to peripheral compartment (K12, 2.69/h). The rate of CRM transfer from the peripheral to central compartment (K21, 0.15/h) was slow. This encourages higher tissue levels of CRM as compared with plasma levels. The study provides an explanation of the therapeutic efficacy of CRM, despite very low/undetectable levels in the plasma.

Determination of the Pharmacokinetics and Oral Bioavailability of Salicylamine, a Potent γ-Ketoaldehyde Scavenger, by LC/MS/MS

March 2010

·

227 Reads

Levels of reactive γ-ketoaldehydes derived from arachidonate increase in diseases associated with inflammation and oxidative injury. To assess the biological importance of these γ-ketoaldehydes, we previously identified salicylamine as an effective γ-ketoaldehyde scavenger in vitro and in cells. To determine if salicylamine could be administered in vivo, we developed an LC/MS/MS assay to measure salicylamine in plasma and tissues. In mice, half-life (t(1/2)) was 62 minutes. Drinking water supplementation (1-10 g/L) generated tissue concentrations (10-500 μM) within the range previously shown to inhibit γ-ketoaldehydes in cells. Therefore, oral administration of salicylamine can be used to assess the contribution of γ-ketoaldehydes in animal models of disease.

Enhanced Cellular Delivery and Biocompatibility of a Small Layered Double Hydroxide–Liposome Composite System

December 2014

·

304 Reads

The various classes of gene delivery vectors possess distinct advantages and disadvantages, each of which impacts on cargo loading, delivery and, ultimately, its function. With this in mind, herein we report on a small layered double hydroxide (sLDH)-liposome composite system, drawing upon the salient features of LDH and liposome classes of vectors, while avoiding their inherent shortfalls when used independently. sLDH-liposome composites were prepared by the hydration of freeze-dried matrix method. These composite systems, with a Z-average size of ≈200 nm, exhibited low cytotoxicity and demonstrated good suspension stability, both in water and cell culture medium after rehydration. Our studies demonstrate that short dsDNAs/ssDNAs were completely bound and protected in the composite system at an sLDH:DNA mass ratio of 20:1, regardless of the approach to DNA loading. This composite system delivered DNA to HCT-116 cells with ≈3-fold greater efficiency, when compared to sLDH alone. Our findings point towards the sLDH-liposome composite system being an effective and biocompatible gene delivery system.

Figure 1. Digital image of bombax gum dispersed in water. 
Figure 2. Viscosity as a function of shear rate for bombax gum. 
Figure 3. Particle size distribution of granules prepared from different binders.
Table 3 . Outcomes of mathematical modeling of drug release profiles.
Table 5 . Composition of granules for tablet formulation.
Application and Characterization of Gum from Bombax buonopozense Calyxesas an Excipient in Tablet Formulation

December 2012

·

1,295 Reads

This study was undertaken to explore gum from Bombax buonopozense calyxes as a binding agent in formulation of immediate release dosage forms using wet granulation method. The granules were characterized to assess the flow and compression properties and when compressed, non-compendial and compendial tests were undertaken to assess the tablet properties for tablets prepared with bombax gum in comparison with those prepared with tragacanth and acacia gums. Granules prepared with bombax exhibited good flow and compressible properties with angle of repose 28.60°, Carr's compressibility of 21.30% and Hausner's quotient of 1.27. The tablets were hard, but did not disintegrate after one hour. Furthermore, only 52.5% of paracetamol was released after one hour. The drug release profile followed zero order kinetics. Tablets prepared with bombax gum have the potential to deliver drugs in a controlled manner over a prolonged period at a constant rate.

Figure 2. Linear scale plots of shear rate vs shear stress for QUE-loaded PEVs. 
Figure 3. Frequency sweep spectra for PEVs: storage (G') and loss (G") moduli against frequency are shown. 
Figure 4. Determination of QUE deposition into pig skin layers (SC, stratum corneum; Ep, epidermis; D, dermis and RF, receptor fluid) after 8-h non-occlusive treatment: (a) QUE loaded in PEVs, (b) coarse dispersions of P50, PE and non-incorporated QUE. Each value is the mean ± S.D. of six experimental determinations. 
Figure 4. Cont. 
Effect of Penetration Enhancer Containing Vesicles on the Percutaneous Delivery of Quercetin through New Born Pig Skin

December 2011

·

226 Reads

Quercetin (3,3',4',5,7-pentahydroxyflavone) exerts multiple pharmacological effects: anti-oxidant activity, induction of apoptosis, modulation of cell cycle, anti-mutagenesis, and anti-inflammatory effect. In topical formulations quercetin inhibits oxidative skin damage and the inflammatory processes induced by solar UV radiation. In this work, quercetin (2 mg/mL) was loaded in vesicular Penetration Enhancer containing Vesicles (PEVs), prepared using a mixture of lipids (Phospholipon® 50, P50) and one of four selected hydrophilic penetration enhancers: Transcutol® P, propylene glycol, polyethylene glycol 400, and Labrasol® at the same concentration (40% of water phase). Photon Correlation Spectroscopy results showed a mean diameter of drug loaded vesicles in the range 80-220 nm. All formulations showed a negative surface charge and incorporation efficiency in the range 48-75%. Transmission Electron Microscopy confirmed that size and morphology varied as a function of the used penetration enhancer. The influence of PEVs on ex vivo quercetin (trans)dermal delivery was evaluated using Franz-type diffusion cells, new born pig skin and Confocal Laser Scanning Microscopy. Results showed that drug delivery is affected by the penetration enhancer used in the PEVs' formulation.

Vaccine Safety Surveillance Systems: Critical Elements and Lessons Learned in the Development of the US Vaccine Safety Datalink’s Rapid Cycle Analysis Capabilities

March 2013

·

1,814 Reads

Since the late 1990s, there have been tremendous strides made in improving the capacity for carrying out routine active surveillance of new vaccines in the United States. These strides have led to new surveillance systems that are now in place. Some of the critical elements that are part of successful vaccine or drug safety surveillance systems include their use of (i) longitudinal data from a discrete enumerated population base, (ii) frequent, routine transfers of small amounts of data that are easy to collect and collate, (iii) avoidance of mission creep, (iv) statistical capabilities, (v) creation of an "industrialized process" approach and (vi) political safe harbor.

Top-cited authors