In absence of dedicated children formulation, intravenous formulations of midazolam, which exhibit strong bitterness, are occasionally used for oral or sublingual administration. In order to improve the quality and the acceptance by children of a midazolam anesthesia premedication, a new 0.2% (w/v) aqueous solution for oral administration has been prepared. The final formulation was obtained by the adjunction of a sweetener (sucralose), an aroma (orange aroma) and gamma-cyclodextrin to a citric acid solution of midazolam. The gamma-cyclodextrin forms an inclusion complex with the hydrophobic midazolam as evidenced using nuclear magnetic resonance spectroscopy (stoichiometry 1:1, K=283 M(-1)). A sterile filtration method was selected for the formulation microbial preservation using liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS). Finally, a routine high performance liquid chromatography (HPLC) method is proposed for the quantitative determination of global midazolam amount in the pharmaceutical preparation.
Little is known about chronopharmacokinetics of PDE V inhibitors in rats as well as in humans. Hence, the pharmacokinetics of DA-8159 and one of its metabolites, DA-8164, were investigated after intravenous and oral administration of DA-8159 at a dose of 30 mg/kg administered at 10:00 h versus 22:00 h in rats. After intravenous administration of DA-8159 at 22:00 h, the AUC of DA-8159 was significantly greater (528 versus 368 microg min/ml) due to significantly slower CL (56.1 versus 79.5 ml/min/kg) in the rats. After intravenous administration of DA-8159 at 22:00 h, the AUC of DA-8164 was also significantly greater (108 versus 66.8 microg min/ml) possibly due to significantly greater exposure of the parent drug (AUC of DA-8159). After intravenous administration of DA-8164 at 22:00 h, the CL of DA-8164 was significantly slower; hence, this factor could also contribute to the greater AUC of DA-8164 after intravenous administration of DA-8159. However, after oral administration of DA-8159, the AUC values of both DA-8159 and DA-8164 were not significantly different between 10:00 h and 22:00 h. This was not due to decrease in gastrointestinal absorption of DA-8159 at 22:00 h and may be due to changes in intestinal first-pass effect at 22:00 h. The above data suggested that modification of dosage regimen of oral DA-8159 is not necessary in humans between 10:00 h and 22:00 h. Further studies are needed in humans.
A protein kinase inhibitor UCN-01 binds with high affinity to human alpha 1-acid glycoprotein (hAGP) which may compromise the drugs therapeutic effectiveness. Liposomal formulations of UCN-01 have been evaluated as a means of reducing the impact of binding to hAGP. However, in an initial study, UCN-01 was released rapidly from liposomes added to rat plasma containing hAGP. The purpose of this study was to develop a liposomal formulation of UCN-01 that only slowly released drug. Liposomes composed of lipids with a high phase transition temperature and having an average particle size of 120 nm and above reduced leaking of UCN-01 when the formulations were evaluated by adding to rat plasma containing hAGP. Furthermore, formulations composed of larger liposomes were also more effective in vivo; in tests in which liposomal preparations were injected together with hAGP into rats, more UCN-01 was retained in liposomes for 24h after administration of 155 nm liposomes as compared to 112 nm liposomes.
Film coating is a technique widely used in the pharmaceutical field to improve and modify technological and release characteristics of capsules, tablets and granules. In this paper physical and mechanical properties of free films of Amprac 01, obtained by the solvent cast method, were studied in order to investigate the film forming ability of this modified starch and the effects of the addition of different plasticizers. A morphological microscopical analysis (SEM) was performed to study surface properties of the films, while thermal analysis (DSC) was carried out to investigate the influence of different types of plasticizers on the glass transition temperature of the polymer. Then a mechanical characterization permitted to evaluate important parameters such as film crack resistance and deformation at break. Extensional creep/relaxation tests were also performed to investigate the viscoelastic characteristics. As clearly demonstrated by the T(g) values, the residual water present in the films acted as plasticizers, making possible the formation of free films characterised by good macroscopical and mechanical properties. Except glycerol, the kind and amount of the other tested plasticizers did not markedly improve the mechanical and crack resistance of the films.
The objective of this work was to assess the antifungal activity of a tropically stable formulation of amphotericin B (AmB) (iCo-010) over short period of treatment in a rat model of invasive candidiasis. The rats were infected with Candida albicans (ATCC 18804); 48 h later, the animals were assigned either to a control group, AmBisome(®) group (5 mg/kg QD), or iCo-010 groups (0.5, 1, 2.5, 5 and 10 mg/kg TID). The animals were treated for two days and then sacrificed 18 h following the completion of the treatment. The blood, liver, lungs, kidneys and spleen were harvested to assess the colony forming units in the samples. There was no significant difference in the reduction of the fungal burden in the organs between the AmBisome(®) and iCo-010 groups except in the spleen and liver. There was a linear correlation between the antifungal activity in renal tissues and the administered doses of iCo-010. The plasma creatinine levels were not significantly different among the control and all the treatment groups. Oral iCo-010 has high efficacy against invasive candidiasis in renal and pulmonary tissues. Longer treatment period than the two-days regimen should be considered for higher therapeutic efficacy of iCo-010 in all the tissues.
The goal of this study was to demonstrate that MK-0364 solid dispersions can be developed as a means to increase the solubility and bioavailability of a poorly water-soluble drug, MK-0364. The potential solid dispersions would enable an oral solid dosage form as a monotherapy or combination product of MK-0364. Preliminary screening included sample preparation via a solvent casting method, physical characterization, and in vitro dissolution testing. Lead formulations were subsequently manufactured using hot melt extrusion (HME) and spray-drying (SD). All HME (without polyvinyl pyrrolidone) and SD formulations exhibit characteristics of a single phase glass including an amorphous halo when analyzed with X-ray powder diffraction (XRPD), a single glass transition temperature (Tg) measured with differential scanning calorimetry (DSC), and supersaturation when dissolved in dissolution media. The oral absorption of MK-0364 from selected HME and SD formulations in monkeys results in marginally greater exposure with a consistently longer Tmax relative to a liquid filled capsule reference. Based on the processability, physical characterization, in vitro dissolution, and animal pharmacokinetic results, copovidone- and hydroxypropyl methylcellulose acetate succinate (HPMCAS)-based solid dispersion formulations are viable product concepts. The physical stability of both the solid dispersion formulations was also evaluated for 54 weeks under different conditions. The copovidone-based solid dispersion requires protection from moisture.
AG-041R is characterized to be stable in amorphous state and difficult to crystallize at normal period of time. In order to investigate the molecular mobility in microscopically, the spin-lattice relaxation time (T1) of AG-041R was investigated by solid-state CP/MAS 13C NMR at temperature below and above glass transition temperature (Tg).
CP/MAS measurement and T1 measurement were performed by means of 13C NMR, where the measurement temperatures were 60, 70, 80, 100, and 110 degrees C. The spin-lattice relaxation time (T1) of AG-041R was calculated from the relaxation curves.
From the analysis of T1 of amorphous AG-041R, it was clarified that all of the carbons did not start moving drastically at Tg and there were some groups of carbon in terms of temperature dependency of T1. One is a type, such as the carbons in benzene ring: their T1 was drastically changed at Tg. On the other hand, T1 of carbonyl carbons gradually decreased, and above Tg their T1 was still higher than that of the other carbons. There was no significant change of T1 in the methyl carbons around Tg. From the study of IR and 1H NMR in solution, the inter- and intramolecular hydrogen bondings between NH and C=O were found in AG-041R. Due to hydrogen bonding, the inter- and/or intramolecular interaction is considered to retain even at supercooled liquid state.
The structure that contributes glass transition is the main skeleton structure, such as benzene ring, while small group, like methyl, start to move at lower temperature than Tg. On the other hand, for the carbons, such as carbonyl, their structure was restricted by inter- and/or intramolecular interaction, therefore, their molecular mobility was significantly low above Tg.
The nasal route has been receiving attention for the administration of systemically active drugs because delivery is convenient, reliable and rapid. The aims of this study were to investigate the systemic absorption of nasally administered (3aS)-cis-1, 2, 3, 3a, 8, 8a-hexahydro-1, 3a, 8-trimethyl-pyrrolo-[2,3b]-indol-5-yl 3, 4 dihydro-2-isoquinolincarboxylate (NXX-066), a physostigmine analogue, in rats and to compare the uptake of the drug into the cerebrospinal fluid (CSF) after nasal and intravenous administration. NXX-066 (3 micromol/kg) was administered to both nostrils or into the vena jugularis of male Sprague-Dawley rats. Blood and CSF samples were obtained at regular intervals from the arteria carotis and by cisternal puncture, respectively. The concentrations of NXX-066 in the blood and CSF samples were measured using HPLC with fluorescence detection. NXX-066 was absorbed rapidly after nasal administration with the peak concentration occurring within 1.5 min. The nasal bioavailability of NXX-066 was 100+/-30% and the elimination from plasma was as rapid as that following intravenous administration. Low concentrations of NXX-066 were detected in the CSF after both intravenous and nasal administration. In conclusion, NXX-066 was rapidly and totally absorbed into the systemic circulation and uptake into the CSF was not enhanced by nasal administration in rats.
MK-0869 (aprepitant), a potent substance P antagonist, is the active ingredient of EMEND which has recently been approved by the FDA for the prevention of chemotherapy-induced nausea and vomiting. Early clinical tablet formulations of MK-0869 showed significant food effects on absorption, suggesting that formulation could have a significant role in improving bioavailability. A Beagle dog model was developed in an effort to guide novel formulation development. Using the suspension of the micronized bulk drug used for the tablet formulations, the food effect on absorption was confirmed in the dog at a similar magnitude to that observed in humans. Further dog studies demonstrated a clear correlation between particle size and in vivo exposures, with the nanoparticle (NanoCrystal) colloidal dispersion formulation providing the highest exposure, suggesting dissolution-limited absorption. The NanoCrystal dispersion also eliminated the food effect on oral absorption in the dog at a dose of 2mg/kg. Regional absorption studies using triport dogs indicated that the absorption of MK-0869 was limited to the upper gastrointestinal tract. These results provided strong evidence that the large increase in surface areas of the drug nanoparticles could overcome the narrow absorption window and lead to rapid in vivo dissolution, fast absorption, and increased bioavailability. In addition, the dog model was used for optimizing formulation processes in which the nanoparticles were incorporated into solid dosage forms, and for selecting excipients to effectively re-disperse the nanoparticles from the dosage units. The human pharmacokinetic data using the nanoparticle formulation showed excellent correlations with those generated in the dog.
This study was conducted to clarify the penetration properties of 4-[1-hydroxy-1-methylethyl]-2-propyl-1-[4-[2-[tetrazole-5-yl]phenyl]phenyl]methylimidazole-5-carboxylic acid monohydrate (CS-088), an ophthalmic agent, and the mechanism of the permeability-enhancing effect of EDTA and boric acid (EDTA/boric acid) on the corneal penetration of CS-088. In the absence of additives, corneal permeability decreased with increasing concentration of CS-088 as CS-088 monomers self-associate to form dimers. Presence of EDTA/boric acid caused no significant changes in the physicochemical properties of CS-088, the apparent partition coefficient or the mean particle size of CS-088. EDTA/boric acid induced only a slight change in the zeta potential of liposomes used as a model of the biological membrane. On the other hand, EDTA/boric acid significantly increased membrane fluidity of liposomes, whereas other buffering agents tested did not. This effect was synergistic and concentration-dependent for both EDTA and boric acid as was observed in in vitro corneal penetration of CS-088. In accordance with the result, the rate of CS-088 permeation into the liposomes significantly increased by the addition of EDTA/boric acid. Therefore, it was demonstrated that EDTA/boric acid promotes corneal penetration of CS-088 through the transcellular pathway by increasing membrane fluidity. Conversely, other buffering agents decreased corneal permeability of CS-088 by inducing further self-association of CS-088 aggregates.
In order to investigate the effects of EDTA and boric acid (EDTA/boric acid) on the corneal penetration of CS-088, an ophthalmic agent, the apparent permeability coefficient of CS-088 in the presence of EDTA/boric acid across the isolated corneal membranes of rabbits was measured using an in vitro penetration chamber system. FITC-dextran (M.W. 4400) and an electrical method based on membrane resistance were used to provide a quantitative assessment of the enhancing effect of EDTA/boric acid. The corneal penetration of CS-088 was significantly enhanced in the presence of EDTA/boric acid by approximately 1.6-fold. The permeability-enhancing effect of EDTA/boric acid was apparently synergistic and concentration-dependent on both EDTA and boric acid. The penetration of FITC-dextran, a paracellular marker, and electrical resistance of corneal membranes were not affected in the presence of EDTA/boric acid. Furthermore, no enhancing effect of EDTA/boric acid was observed in de-epithelialized corneas, although de-epithelialized corneas exhibited a markedly higher permeability of CS-088 that was 24-fold greater than that for intact corneas. In conclusion, EDTA/boric acid synergistically enhances the transcellular permeability of CS-088 in the outer layer but not in the inner layers of the corneal membrane.
Self-association properties of CS-088, an antiglaucoma ophthalmic agent, were investigated. Various analytical methods, such as surface tension measurement, demonstrated that CS-088 is a self-associating compound with critical micellar concentration (CMC) of approximately 10 mg/mL. Light scattering analysis revealed that the micellar molecular weight (MMW) of CS-088 aggregates well above the CMC was approximately 2260, corresponding to a pentamer. In addition, the MMW corresponding to a dimer was detected by NMR spectroscopy, indicating that self-association of monomers to pentamers is via the formation of dimers. According to the Stokes-Einstein equation, hydrodynamic radii of the dimer and pentamer were calculated to be 0.87 and 1.16 nm, respectively. The concentration-dependent change in the NMR chemical shift indicated that hydrophobic interaction between biphenyl groups is an important factor in the self-association of CS-088 molecules. Furthermore, measurement of particle size distribution using a Nicomp Submicron Particle-Sizer revealed that the addition of either n-propanol or urea to CS-088 solution led to monomerization of the dimers and pentamers, suggesting that not only hydrophobic interaction but also hydrogen bonding is involved in stabilizing CS-088 aggregates. No bigger aggregate than a pentamer was formed in the absence of NaCl, whereas further aggregation was observed with increasing concentrations of NaCl.
Interaction of norfloxacin and ofloxacin with copper(II) and copper(II)/phenanthroline has been studied in aqueous solution and the stability constants of the binary complexes Cu(II)/fluoroquinolone and of the ternary complexes Cu(II)/phenanthroline/fluoroquinolone have been determined by potentiometry and UV-vis spectrophotometry. The stability constants for the binary and ternary complexes of norfloxacin were always higher than those found for ofloxacin and comparing the values obtained for the binary and ternary species (DeltalogK) it is possible to conclude that the ternary complexes are more stable than the binary ones, suggesting that an interaction occurs between the ligands in the ternary complexes. From the distribution diagrams it is possible to state that at physiological pH 7.4, the copper ternary complexes, are the main species in solution not only at the concentration used to determined the stability constants but also at the minimum inhibitory concentration. The antibacterial activity of these complexes, in different bacterial strains, was determined, at physiological pH, and the results obtain show that these ternary complexes may be good candidates as metalloantibiotics.
The objective of this study was to investigate the percutaneous absorption of metronidazole (MTZ) in the topical formulations containing a combination of 1,4-cyclohexanediol and 1,2-hexanediol. Six formulations were studied in an in vitro hairless mouse skin model using Franz Diffusion Cell. MTZ was applied at infinite doses (50mg and 100mg of the formulations, which correspond to 375 and 750 μg of MTZ, respectively). Based on the flux values and retardation ratio (RR), a synergistic retardation effect on percutaneous absorption of MTZ was observed for the formulations containing a combination of 1,4-cyclohexanediol and 1,2-hexanediol (RRs are 0.40 for 375 μg dose and 0.69 for 750 μg dose, respectively). Interestingly, retention of MTZ in epidermis and dermis layer showed no significant differences (p>0.05) between the formulations containing the retardant combination and control formulations. In other words, the retardant combination in the formulation decreases MTZ fluxes while maintaining similar level of retention in epidermis and dermis layer when compared to the control formulations. These observations provide insight in formulating superior topical formulations with minimized potential systematic toxicity while maintaining therapeutic efficiency. A mechanistic explanation of the observed synergistic effect is proposed.
3-l-Menthoxypropane-1,2-diol (MPD) is a derivative of l-menthol, which has an enhancement effect on drug permeation through skin. In this study, the effect of MPD on drug permeation through skin was compared with that of l-menthol. MPD or l-menthol at final concentrations of 3% in 40% ethanol was added to the drugs indomethacin or antipyrine and each mix then applied to Yucatan micropig skin in vitro. Drug concentrations in the skin were higher in the presence of either MPD or l-menthol, however, only l-menthol shortened the lag time of permeation. MPD enhanced the skin permeation of the drugs only by increasing the skin concentration of the drugs. In contrast, l-menthol enhanced the skin permeation of the drugs by increasing both the skin concentration and the diffusion rate in skin. The infrared (IR) spectra and X-ray diffraction patterns of stratum corneum after treatment with MPD did not differ from those of intact stratum corneum. A change in the IR spectra of stratum corneum after treatment with l-menthol was observed at the CH band, and the peaks representative of the lipid structure in the X-ray diffraction patterns decreased in intensity. These results suggest that l-menthol, but not MPD, disrupts the intercellular lipid structure of stratum corneum. Thus, MPD is expected to be a moderate skin permeation enhancer.
The influence of hydrophobic-block length on solubilisation capacity was examined for micelles of E(m)B(n) copolymers (E=oxyethylene, B=oxybutylene, subscripts denote number-average block lengths in repeat units) with B-block lengths in the range of 30-76 and with E-blocks of sufficient length to ensure the formation of spherical micelles. Griseofulvin was used as a model poorly-water-soluble drug known to be almost exclusively solubilised in the micellar core. Combination of solubilisation data with those of a previous study has shown that the amount of drug solubilised per gram of hydrophobe is essentially independent of B-block length when this exceeds about 15 B units, suggesting that core size is not a major influence on solubilisation.
The dependence of log(cmc) on hydrophobic block length n was examined for E(m)B(n) copolymers (E=oxyethylene, B=oxybutylene, subscripts denote number-average block lengths in repeat units) with n in the range 30-76. Combination with published data for E(m)B(n) diblock copolymers with shorter E-blocks shows two changes of slope in the log(cmc)-n plot corresponding to the onset of unimolecular micelle formation at n approximately 12 and completion of this process at n approximately 30. The results are discussed with reference to published data for E(m)L(n) and E(m)CL(n) (L from d,L-lactide; CL from epsilon-caprolactone) copolymers, which show similar behaviour.
Stability studies of 2-hydroxymethyl-4,8-dibenzo[1,2-B:5,4-b']dithiophene-4,8-dione (NSC 656240, dithiophene), a poorly water-soluble (approximately 5 microg/ml) potential anticancer drug are reported. Dithiophene stability turned out to be very sensitive to laboratory fluorescent lighting. The rate of photodegradation of dithiophene was studied in aqueous solutions at room temperature (approximately 25 degrees C) at various pH values, in MeOH, CH(3)CN, DMF, DMA, and in mixed nonbuffered aqueous/organic solutions. The aqueous pH-rate profile indicated no sensitivity to changing pH values. 1H NMR and LC/MS methods were used to characterize the degradation products. Dithiophene photodegradation in the presence of air followed an apparent autoxidation pathway with dithiophene-2-aldehyde and dithiophene-2-carboxylic acid as the major degradants. The structures were confirmed against authentic samples. Dithiophene photodegradation under anaerobic conditions followed an apparent disproportionation pathway with only one identified major product, dithiophene-2-aldehyde.
Alcohol and glycol including 1,2-pentanediol, a new product in this field, were examined for their transdermal penetration enhancing in vitro properties using pig skin and caffeine as a model drug. In order to investigate a possible influence of these compounds, we followed diffusion from an aqueous solution with caffeine followed by a series of different vehicles, their compositions were: (1) in water as a control; (2) in propylene glycol/ethanol/water (25:25:48; v/v/v); (3) in 1,2-pentanediol/water (2.5:95.5, v/v); (4) in 1,2-pentanediol/water (5:93, v/v); in propylene glycol/water (5:93; v/v); and in ethanol/water (5:93; v/v). The stratum corneum/vehicle partition coefficients (K(m)), maximum flux (J), enhancement factor (EF), 24-h receptor concentration (Q(24h)) were determined and compared to control values (caffeine in water). Permeation was also expressed in percentage of the applied dose absorbed in the different compartments. In all test models, caffeine was released and penetrated into pig skin. The 1,2-pentanediol was presented as the most effective enhancer; with a low proportion of this compound (only 5%), caffeine penetrated the skin quicker and in a greater extent. While this compound showed promise as penetration enhancer, further study was required to determine its effectiveness with others drugs and its irritation potential.
Ethylene oxide and 1,2-butylene oxide were sequentially polymerised to form the diblock copolymer E13B10 (E=oxyethylene, B=oxybutylene, subscripts denote number-average block lengths in repeat units). Dynamic and static light scattering over the temperature range 10-30 degrees C demonstrated a transition from compact (spheroidal) micelles to larger, more elongated (worm-like) micelles with temperature increase above a critical onset temperature of about 20 degrees C. Determination of the solubilisation capacity for griseofulvin, carbamazepine and spironolactone of dilute micellar solutions of this copolymer, together with those of E11B8 and E17B12 block copolymers (which also show the sphere-to-worm transition), allowed investigation of the influence on solubilisation characteristics of hydrophobic block length and temperature. The extent of solubilisation at 25 degrees C of the poorly water-soluble drug spironolactone increased linearly with increase of hydrophobic block length, attributable to a concomitant increase in the proportion of worm-like micelles in solution.
The solubilities in isopropyl myristate (S(IPM)) and pH 4.0 buffer (S(AQ)) and the partition coefficients between IPM and pH 4.0 buffer (K(IPM:AQ)) have been measured for a series of 1,3-bisalkylcarbonyl-5-fluorouracil prodrugs (1,3-AC-5-FU). The 1,3-AC-5-FU prodrugs were each over 500 times more soluble in IPM, but all members of the series, whose solubilities could be estimated, were much less soluble in pH 4.0 buffer than 5-FU. The abilities of the 1,3-AC-5-FU prodrugs to deliver total 5-FU species through hairless mouse skin from IPM suspensions (J(i)) were also measured. The 1,3-diacetyl derivative 2, which exhibited the highest S(AQ) in the series, gave the highest J(i) value. Although the series of 1,3-AC-5-FU prodrugs was generally effective at increasing J(i) (three to ten times), the best 1,3-AC-5-FU prodrug was not as effective as the best 1- or 3-alkylcarbonyl-5-FU prodrug (1- or 3-AC-5-FU) at increasing J(i) and their ability to increase the concentration of total 5-FU species in the skin was generally less than that of the 1-AC-5-FU prodrugs, but greater than that of the 3-AC-5-FU prodrugs. Thus, the 1-AC-5-FU prodrugs remain the best prodrugs with which to enhance the topical delivery of 5-FU.
The purpose of this study was to investigate the potential of new positively charged solid lipid nanoparticles (SLN) to convey nucleic acids. The cationic character of SLN was obtained by adding as cationic molecules two different long-chain cationic phosphines (CP), namely hexadecyl-PTA iodide (CP16) and octadecyl-PTA iodide (CP18). The obtained CP-SLN are characterized by a positive charge on the surface and reproducible dimensions around 220 nm. These nanosystems are able to efficiently bind nucleic acid molecules and to protect DNA from the activity of serum nucleases up to 120 min. Lastly, in vitro experiments demonstrated that CP-SLN exhibit a quite pronounced antiproliferative effect on cultured human K562 erythroleukemic cells and a limited effect as transfecting adjuvant. These data, and particularly the ability of CP-SLN to protect DNA from degradation, encourages further studies aimed at proposing these nanosystems as a potential approach to deliver nucleic acid to cells in living organisms.
The possibility of increasing the photochemical stability of nisoldipine by using indigotine and azorubine as photoprotectors has been studied. The course of the photodegradation was monitored by means of UV-vis spectrophotometry and HPLC. Quantitative assessments of the nisoldipine photodegradation included evaluation of the quantum yields and kinetic parameters. In order to establish the light intensity absorbed by a system, Reinecke salt was used as a chemical actinometer. The values of the quantum yields (phi) of photodegradation decreased with increasing dye concentration and were 0.24-0.15 and 0.27-0.25 for indigotine and azorubine, respectively. Furthermore, our attention was focused on determination the role of the selected dyes during the photodegradation of nisoldipine and the calculations were made to eliminate an inner filter effect. The values obtained were used to construct a Stern-Volmer plot and calculate the Stern-Volmer constants (KSV). On the basis of the KSV and the values of the quenching constant (kq) the exited state lifetime (tauo) of nisoldipine in the presence of indigotine and azorubine were estimated. The calculated values of tauo for NS were 6.66x10(-6)s--in the presence of indigotine and 2.76x10(-6)s--in the presence of azorubine, indicating that the photodegradation of nisoldipine occurs from the lowest triplet excited state.
Cramoll 1,4 is a lectin extracted from seeds of Cratylia mollis Mart. Many assays have shown the cytokine release activity and pro-inflammatory profile of this lectin. Here, we used Cramoll 1,4 in the treatment of cutaneous wounds in normal and immunocompromised mice for available your cicatricial power. Surgical wounds were treated daily with a topical administration of Cramoll 1,4 and parameters as edema, hyperemia, scab, granulation and scar tissues as well as contraction of wounds were analyzed. Cramoll 1,4 wounds showed higher edema and arrival of more polimorphonuclear cells at the site of lesions. Granulation tissue and collagen fiber deposition were observed with higher intensity in all Cramoll 1,4 treated wounds and promoted excellent closing and repair of lesions in less time than other groups. Results showed that Cramoll 1,4 lectin was effective in the repair of experimental lesions in mice and can be used as a future cicatricial compound.
Effect of particle size on the photostability of dimethyl 1, 4-dihydro-2,6-dimethyl-4-(2-nitro-phenyl)-3,5-pyridinedicarboxylate (nifedipine) powder and its tablet was investigated using high-pressure liquid chromatography (HPLC) method and Fourier-transformed infrared reflection-absorption spectroscopy (FT-IR-RAS) under the non-destructive condition. The nifedipine content on the surface of the tablet was determined based on the absorbance at 1682 cm(-1) attributable to the C=O stretch vibration in FT-IR-RAS spectra before and after irradiation by fluorescent lamp. The photodegradation followed apparently the first-order kinetics for any sample. The apparent photodegradation rate constant of nifedipine powder increased with decrease of the particle size, while that of its tablet was approximately constant irrespective of particle size. Semilogarithmic plots of the apparent degradation rate constant for nifedipine tablet against the reciprocal of illuminance demonstrated a linear relationship similar to that of the Arrhenius-type behavior.
The objective of this study is to investigate the effect of 1,4-cyclohexanediol as a retardant on the percutaneous absorption and penetration of azelaic acid. Hairless rat skin was mounted on Franz diffusion cells and treated with topical formulations containing solubilized azelaic acid with and without 1,4-cyclohexanediol. The skin was separated into stratum corneum and the deeper skin layers. The azelaic acid collected in receptor medium and each layer at the end of each time point was extracted and quantified. A significant decrease in flux across the skin suggests a penetration retardation effect of 1,4-cyclohexanediol (42.50 microg/cm(2)/h in the presence of vs. 76.25 microg/cm(2)/h in the absence of) at active loading level of 1.13 mg/cm(2). The penetration retardation effect was also observed at higher active loading level (2.82 mg/cm(2)). Furthermore, presence of 1,4-cyclohexanediol in the topical formulation did not reduce the skin and epidermal retention of azelaic acid, suggesting its potential use in the development of superior topical formation for reducing potential systematic side effect while maintaining therapeutic efficiency.
The effect of gamma and beta radiation in doses between 10 and 100 kGy on physico-chemical properties of four derivatives of 1,4-dihydropyridine (nifedipine, nitrendipine, felodipine and nimodipine) in the solid state was analysed. A number of qualitative and quantitative methods such as UV, IR, TLC, GLC, DSC, EPR as well as organoleptic and gravimetric analysis were used to determine and analyse any changes resulting from irradiation. In order to determine the effectiveness of sterilization with ionizing radiation of doses from 10 to 25 kGy, various microbiological tests were used. It was established that only doses 10-20 kGy of both kinds of radiation ensure total sterilization without any degradation of physico-chemical properties of the compounds studied. For the doses 50-100 kGy a decrease in the content of the compounds, appearance of the products of their decomposition and changes in the melting point and IR spectra appeared. Felodipine (with chlorophenyl substituent) was found to be much more sensitive to ionising radiation than nifedipine, nitrendipine and nimodipine (all with nitrophenyl substituent).
Degradation kinetics of cyclic HPMPC (cHPMPC), 1-[((S)-2-hydroxy-2-oxo-1,4,2-dioxaphosphorinan-5-yl)methyl]cytosi ne, and its parent compound cidofovir (also known as HPMPC) were conducted in the pH range of 2-11 at 70 degrees C. cHPMPC manifested greater chemical stability than cidofovir, except under alkaline conditions (pH?9). Three degradation products-cidofovir, cyclic HPMPU and HPMPU-were identified for cHPMPC, and the product distribution was characterized via a stability-indicating HPLC assay. Cyclic HPMPU and HPMPU are the uracil analogs of cHPMPC and cidofovir, respectively, formed through a hydrolytic deamination pathway. The deamination and hydrolysis rate constants for cHPMPC under acidic conditions were derived from the degradation product curves. The deamination rate constants for cHPMPC were about 8-fold slower compared to that for cidofovir. The enhanced chemical stability for cHPMPC relative to cidofovir is attributed to the absence of intramolecular catalysis with cHPMPC.
N-Epoxymethyl-1,8-naphthalimide (ENA) is a novel antiproliferative drug candidate with potent anticancer and antifungal activity. It has an aqueous solubility of 0.0116mg/mL and also exhibits hydrolytic instability with a first-order hydrolysis rate of 0.051 h(-1). The present preformulation study aimed to characterize the physicochemical properties of ENA and develop an early injectable solution formulation for preclinical studies. To minimize hydrolysis, ENA is proposed to be formulated as either lyophilized powders or nonaqueous solutions followed by solubilization/reconstitution prior to administration. ENA solubilization was investigated in both aqueous media (by cosolvency, micellization and complexation) and nonaqueous solutions (mixture of Cremophor EL and ethanol). It is found that none of the solubilization techniques in aqueous media could increase ENA solubility to a desired level of several hundreds microg/mL at pharmaceutically acceptable excipient concentrations (< or =10%). In contrast, a combination of 70% Cremophor EL and 30% ethanol (v/v) proved effective in solubilizing ENA at 4 mg/mL, which exhibited good physical and chemical stability on storage at both 4 degrees C and room temperature over 4 months. No precipitation was observed upon 5-20 times dilution by the saline; in addition, less than 5% of ENA was hydrolyzed in 4h for the saline-diluted aqueous solutions. This nonaqueous ENA formulation is thus proposed for further preclinical studies, which can be reconstituted, prior to administration, by the 5-20 times infusion fluids (saline, 5% dextrose, etc.) to the desired drug dosing concentration at the acceptable excipient level. The approach used in this work could serve as a useful reference in formulating nonpolar drugs with hydrolytic instability.
Polymeric micelles consisting of poly(ethylene glycol)-distearoyl phosphoethanolamine conjugates (PEG-DSPE) loaded with Vitamin K3 (VK3) to 0.2 mg of drug/mg of carrier and with 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU) to 0.06 mg of drug/mg of carrier were prepared. These micelles were stable for as long as 6 months during storage at 4 degrees C and did not change their size or release the incorporated drugs. Co-encapsulation of VK3 and DBU into PEG-DSPE micelles resulted in synergistic anticancer effects against both murine and human cancer cells in vitro. The synergism may be explained by the fact that the presence of DBU promotes the escape of drug-loaded micelles from the endosomes of cancer cells directly into the cytoplasm as demonstrated by fluorescent microscopy.
The interaction of a potent percutaneous penetration enhancer, 1,8-cineole, with the stratum corneum (SC) and DPPC membranes was investigated by electron paramagnetic resonance spectroscopy (EPR) of spin-labeled analogs of stearic acid (5-DSA) and androstanol (ASL). The EPR spectra of lipid derivatives spin probes structured in stratum corneum tissue of neonatal rat containing of 0.1-10% (v/v) 1,8-cineole in the solvent indicate an abrupt increase in membrane fluidity at around 1% 1,8-cineole. These spectra of stratum corneum membranes are characterized by the presence of two spectral components differing in mobility. Component 1 was attributed to the spin labels H-bonded to the headgroups, while component 2 possibly arose from spin labels H-bonded to water molecules or temporally non-hydrogen-bonded. With the addition of 1,8-cineole, the spin probes were transferred from the motionally more restricted component 1 to the more mobile component 2, suggesting that 1,8-cineole causes ruptures in the hydrogen-bonded network of the membrane-water interface, with consequent displacements of spin probes towards the hydrophobic core. 1,8-Cineole increased the rotational diffusion rates of component 2, whereas no significant mobility changes were observed in component 1. The EPR spectra of maleimide derivative spin label (6-MSL) covalently attached to stratum corneum proteins indicate that 1,8-cineole does not alter the dynamics of protein backbones. Instead, this terpene only increases the solvent's ability to 'dissolve' and mobilize the nitroxide side chain, which is in agreement with its low irritation response.
Baicalin nanosuspensions, stabilized with 10% TPGS (relative to the weight of baicalin), were transformed into nanosuspensions powders by solidification process. Solidification methods for this transformation included freeze-drying, spray drying or vacuum drying. High pressure homogenization was applied for production of baicalin nanosuspensions used TPGS, SDS, P188, HPMC and MC as stabilizer, respectively. The influence of the different solidification transformation methods on the redispersibility of solid drug nanosuspensions was systemically investigated, such as freeze-drying, spray drying and vacuum drying. Each method was applied with three grades of process stresses called as "conservative", "moderate" and "aggressive" conditions, and the redispersibility index(RDI) of nanosuspensions stabilized by stabilizers (such as TPGS, SDS, P188, HPMC and MC) during those process was investigated. The results showed that there was significant difference in RDI of nanosuspensions after solidification process. The RDI(a) (1.09, 1.01, 1.05, 0.99), RDI(b) (1.03, 0.99, 1.06, 1.02) and RDI(c) (1.01, 1.01, 1.09, 1.08) of nanosuspensions stabilized by TPGS was more small during different solidification process, compared with those of nanosuspensions stabilized by other stabilizer. It was concluded that the baicalin nanosuspensions were subjected to agglomeration or crystal growth during solidification transformation, especially at high aggressive stress conditions. Meanwhile, compared to other stabilizer, the TPGS was more effective for stability of baicalin nanosuspensions, which could exhibit higher affinity to the drug crystal and stronger surface adsorption at different solidification stresses.
Berberine (Ber), an isoquinoline alkaloid, arouses wide interests of many researchers in recent years because of its numerous new pharmacological actions. However Ber's low oral bioavailability restricts its wide application. In this study, a solid dispersion (BPTS-SD) composed of berberine-phospholipid complex (BPC), d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS 1000) and SiO2 was prepared by simple solvent evaporation technique. BPC was employed to improve the liposolubility of Ber, and SiO2 was used to improve the flowability of BPTS-SD, while TPGS 1000 played a dual role: firstly, as a solid dispersion carrier to improve the dissolution rate of BPC and secondly, as a P-glycoprotein (P-gp) inhibitor to enhance the intestinal absorption of Ber. FTIR, DSC and SEM analysis proved the formation of BPC and BPTS-SD. Po/w of BPC successfully increased from 0.25 to 8.75. In vitro dissolution study showed that the cumulative dissolution percentages of BPTS-SDs were nearly 2.67-4.78 folds of BPC. Single-pass intestinal perfusion studies showed that the absorption of Ber in BPC was increased nearly 1.4-2.0 folds compared to that of Ber which was mainly due to the improved liposolubility, and further increased by BPTS-SD around 0.1-1.3 folds compared to that of BPC through the P-gp inhibition of TPGS 1000. Significant improvements in Cmax and AUC0→t of BPC and BPTS-SD were obtained in pharmacokinetic study (the highest improvement in oral relative bioavailability of BPTS-SD-1 was 322.66% of Ber). All these results indicated that BPTS-SD can be a promising drug delivery system to improve their oral bioavailability for the Ber's analogues. In particular this solid dispersion can be prepared just by a simple method and has a strong feasibility for industrialization.
Micelles from the mixture of poly(ethylene glycol)-phosphatidyl ethanolamine conjugate (PEG-PE) and d-alpha-tocopheryl polyetheyene glycol 1000 succinate (TPGS) were prepared loaded with the poorly soluble anticancer drug camptothecin (CPT). The solubilization of CPT by the mixed micelles was more efficient than with earlier described micelles made of PEG-PE alone. CPT-loaded mixed micelles were stable upon storage and dilution and firmly retained the incorporated drug. The cytotoxicity of the CPT-loaded mixed micelles against various cancer cells in vitro was remarkably higher than that of the free drug. PEG-PE/TPGS mixed micelles may serve as pharmaceutical nanocarriers with improved solubilization capacity for poorly soluble drugs.
d-alpha-Tocopheryl polyethylene glycol 1000 succinate (TPGS) was used as a novel additive to the poly(l-lactide) (PLLA) films for local drug delivery with paclitaxel as a prototype therapeutic agent. Paclitaxel-loaded PLLA/TPGS films were prepared by the solvent casting technique with dichloromethane as the solvent. Effects of TPGS component on the films' physicomechanical properties and the drug release profile were investigated. It was found by field emission scanning microscopy (FESEM) that a biphasic honeycomb surface was formed for the PLLA/TPGS films, while the PLLA film exhibited a smooth and homogeneous surface. There was no significant effect of the drug loading on the morphological structure of the PLLA/TPGS films. Differential scanning calorimetry (DSC) demonstrated that the PLLA/TPGS films was a phase-separated system. Tensile testing showed that the flexibility of the PLLA/TPGS films was much higher than that of the PLLA film. The elongation at break for the PLLA/TPGS film of 5%, 10% and 15% TPGS content was 6.8, 8.9 and 19.4 times of that for the PLLA film, respectively. In vitro drug release studies found that incorporation of TPGS considerably facilitated paclitaxel release.
Vancomycin hydrochloride (VCM) is a glycopeptide antibiotic used for the treatment of infections caused by methicillin-resistant staphylococci. It is water soluble, having a high molecular weight, and poorly absorbed from the gastrointestinal tract. Mixtures of VCM with Labrasol and D-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS) were prepared to improve oral absorption of VCM. Administration of VCM solution to rat ileum at a dose of 20 mg/kg did not result in detectable plasma VCM concentration. Formulation containing 50% of Labrasol resulted in a Cmax value of 5.86+/-0.97 microg/ml and an AUC(0-6h) value of 16.06+/-1.78 microgh/ml. Addition of TPGS to VCM solution at 12.5% concentration also increased the plasma VCM concentration with a Cmax value of 4.98+/-0.45 microg/ml. But the AUC(0-6 h) (9.87+/-1.90 microgh/ml) was significantly lower than that obtained with Labrasol. The addition of 5.0 and 25.0% TPGS to solutions of VCM containing 50% of Labrasol did not result in any significant increase either in Cmax or AUC(0-6 h) of VCM. Whereas the addition of 12.5% of TPGS has resulted in an increase in Cmax and AUC(0-6 h) by 2.2 and 2.4 times, respectively, suggesting that this concentration of 50% Labrasol and 12.5% TPGS (1:0.25) was optimum for improving intestinal absorption of VCM. A dose dependent decrease in the Cmax and AUC(0-6 h) values was observed when the dose of absorption enhancers was decreased by 50% with formulation containing Labrasol and TPGS in 1:0.25 ratio. The results of the study indicate that formulations containing Labrasol and TPGS improve intestinal absorption of hydrophilic macromolecular drug, VCM.
Tight junctions (TJs) are intercellular structures that control paracellular permeability and epithelial polarity. It is now accepted that TJs are highly dynamic structures that are regulated in response to exogenous and endogenous stimuli. Here, we provide details on the mechanism of action of AT-1002, the active domain of Vibrio cholerae's second toxin, zonula occludens toxin (ZOT). AT-1002, a hexamer peptide, caused the redistribution of ZO-1 away from cell junctions as seen by fluorescence microscopy. AT-1002 also activated src and mitogen activated protein (MAP) kinase pathways, increased ZO-1 tyrosine phosphorylation, and rearrangement of actin filaments. Functionally, AT-1002 caused a reversible reduction in transepithelial electrical resistance (TEER) and an increase in lucifer yellow permeability in Caco-2 cell monolayers. In vivo, co-administration of salmon calcitonin with 1 mg of AT-1002 resulted in a 5.2-fold increase in AUC over the control group. Our findings provide a mechanistic explanation for AT-1002-induced tight junction disassembly, and demonstrate that AT-1002 can be used for delivery of other agents in vivo.
The primary aim of this study was to investigate the skin permeation-enhancing mechanism of HPE-101 using erythrocyte ghost cells prepared from human whole blood as a biomembrane model. The extent of hemolysis of erythrocytes induced by HPE-101 was measured using a spectrophotometer at 540nm. The effect of HPE-101 on lipid fluidity was examined by observing the change of intramolecular excimer formation and fluorescence polarization using an intramolecular probe (1,3-bis(pyrene) propane) and a lipid probe (1,6-diphenyl 1,3,5-hexatriene), respectively. Hemolysis of erythrocytes was observed at 0.01mM and completed at 1.0mM of HPE-101. The fluorescence polarization of the ghost membrane decreased with the addition of HPE-101, whereas the intramolecular excimer formation increased. HPE-101 thus enhanced the rotational mobility and the lateral diffusion, thereby decreasing the microviscosity of ghost membranes, implying that HPE-101 increases the lipid fluidity of ghost membranes. Therefore, HPE-101 seems to cause an increase in fluidity of the lipid bilayers in the stratum corneum of the skin, resulting in the reduction of diffusion resistance.
The objective of the present study was to characterise and optimise the desolvation process of human serum albumin (HSA) for the preparation of nanoparticles and to characterise the resulting colloidal system. Following the desolvation of the protein, the resulting nanoparticles were stabilised by the addition of varying amounts of glutaraldehyde or by heat denaturation. The particle size, zeta potential, and the number of available amino groups on the surface of the nanoparticles were determined. The amino groups were quantified by a spectrophotometric method using 2,4, 6-trinitrobenzenesulfonic acid (TNBS). The results indicated that the particle size depended mainly on the amount of desolvating agent added, but not on the amount of cross-linker or the kind of cross-linking procedure. Increasing amounts of glutaraldehyde reduced the number of amino groups on the surface of HSA nanoparticles and also decreased the zeta potential of the carrier system. The temperature and heat denaturation time only had an influence on the stability of the nanoparticles but not on the amount of amino groups or the particle size. It was shown that heat denatured HSA nanoparticles possessed the greatest number of amino groups on their surface. Additional experiments for the characterisation of gelatin A and B nanoparticles were performed.
The effect of the amoxicilline as a possible cisplatin-action protector on pBR322 DNA has been visually studied by atomic force microscopy in comparison with the modifications caused by the controversed cisplatin protector amifostine. Incubation of amoxicilline with the plasmid DNA showed aggregation and compaction of DNA. Cisplatin incubated in the same conditions with DNA produced kinks and super-coiling of the circular form. In the case of previous treatment of DNA with amoxicilline, the characteristic effect of cisplatin is only partially observed. The amoxicilline seemed to control the action of cisplatin on DNA. The initial effect of dephosphorylated amifostine (WR-1065) when this protector was incubated with the plasmid was also the formation of aggregates and the compaction of DNA. However, addition of cisplatin successively after 1 and 2 h showed the characteristic modification caused by cisplatin but only in a decreasing percentage of molecules of DNA. Both molecules, amoxicilline and WR-1065 seem to control the strong direct action of cisplatin on DNA. This effect can justify the role as protecting agent of amifostine on side effects caused by cisplatin and can open new possibilities to other agents like amoxicilline.
The aims of this study were the development, characterization and bioevaluation of a novel biocompatible, resorbable and bio-active wound dressing prototype, based on anionic polymers (sodium alginate - AlgNa, carboximethylcellulose - CMC) and magnetic nanoparticles loaded with usnic acid (Fe3O4@UA). The antimicrobial activity was tested against Staphylococcus aureus grown in biofilms. The biocompatibility testing model included an endothelial cell line from human umbilical vein and human fetal progenitor cells derived from the amniotic fluid, that express a wide spectrum of surface molecules involved in different vascular functions and inflammatory response, and may be used as skin regenerative support. The obtained results demonstrated that CMC/Fe3O4@UA and AlgNa/Fe3O4@UA are exhibiting structural and functional properties that recommend them for further applications in the biomedical field. They could be used alone or coated with different bio-active compounds as Fe3O4@UA for the development of novel, multifunctional porous materials used in tissues regeneration, as antimicrobial substances releasing devices, providing also a mechanical support for the eukaryotic cells adhesion, and exhibiting the advantage of low cytotoxicity on human progenitor cells. The great antimicrobial properties exhibited by the newly synthesized nano-bioactive coatings, are recommending them as successful candidates for improving implanted devices surfaces used in regenerative medicine.
This paper reports the effect of disintegrant hygroscopicity on dissolution of tablets obtained by compression at 85 MPa of mixtures of Norfloxacin and different proportions of a disintegrant (Starch 1500, PVP XL 10 or Croscarmellose sodium) and a diluent (Pharmatose DCL 11). Dissolution behavior was evaluated according to USP 23, apparatus 2 (paddle) at 50 rpm and using 750 ml acetate buffer solution of pH 4, at 37 degrees C, as medium. Norfloxacin added of increasing proportions, in a given range, of each disintegrant or the diluent increased the drug dissolved. Addition of increasing proportions of Pharmatose DCL 11 to Norfloxacin with 5% of the high hygroscopic Starch 1500 reduced the dissolution improvement effect of Pharmatose DCL 11. Addition of 5% Pharmatose DCL 11 to tablets of the middle hygroscopic Croscarmellose sodium and Norfloxacin slightly reduced the Croscarmellose sodium dissolution promoting effect, while addition of 15% Pharmatose DCL 11 to tablets of the low hygroscopic PVP XL 10 and Norfloxacin showed no inhibition but potentiated substantially the dissolution of Norfloxacin. These effects were attributed to competition for the available water in the tablet and to different water consume, for dissolution or hydration, by the diluent and the disintegrants.
Lyophilized protein formulations sometimes pose problems such as the formation of a cloudy solution upon reconstitution. Ampoule or vial breakage can also occur during the production processes of lyophilized pharmaceutical products. Various efforts have been made to overcome those difficult problems. In this study, we introduce a particular temperature program into the production process of a recombinant human Interleukin-11 (rhIL-11) lyophilized formulation containing sodium phosphates (Na2HPO4/NaH2PO4, pH 7.0) and glycine in an attempt to improve its dissolution properties and to prevent ampoule breakage from occurring. The formulation was pretreated by nucleating ice and maintaining the solution overnight at a temperature of -6 degrees C. The solution was then completely frozen at a lower temperature. This pretreatment proved successful in not only producing a lyophilized cake which readily disintegrated and dissolved in the reconstitution media, but also prevented ampoule breakage from occurring during the production processes. In contrast, a lyophilized cake produced without the pretreatment created a cloudy solution particularly when reconstituted using water for injection contaminated with aluminum (Al3+), although the solution became transparent within 20-30 min. The pretreatment induced the crystallization of sodium dibasic phosphate (Na2HPO4) in the freeze-concentrate whereas direct freezing without the pretreatment did not crystallize the salt. Thermal analyses (DSC and TMA) showed that amorphous sodium dibasic phosphate in the freeze-concentrate became crystallized upon heating, accompanied by an increase in volume, which probably caused the ampoule breakage that occurred without the pretreatment. Although power X-ray diffraction (PXRD) experiments suggested that, with or without the pretreatment, glycine assumed the beta-form and sodium phosphate stayed amorphous in the final products, an electrostatic interaction between dibasic phosphate anions and rhIL-11, a highly cationic protein, would only exist in the lyophilized cake produced without the pretreatment. This interaction is highly likely because aluminum facilitates the formation of a cloudy solution upon reconstitution possibly by using the divalent anions which effectively reduce electrostatic repulsions between aluminum and the protein to form an aggregate structure that is not readily soluble. The pretreatment would circumvent the interaction by crystallizing the sodium salt before freezing creating a relatively soluble lyophilized cake that is much less sensitive to aluminum.
In this work we have studied the conjugation of the immunogenic peptide sequence (110-121) belonging to the VP3 capsid protein of hepatitis A virus to the surface of preformed liposomes by means of an amide bond between the vesicles and the synthetic peptide. The surface activity of the conjugate at air/water interface was determined. Moreover, the interaction of the conjugate with lipids was also studied recording the pressure increases produced after the injection of the liposome-peptide preparation under dipalmitoylphosphatidylcholine (DPPC), dipalmitoylphosphatidylglycerol (DPPG) and stearylamine (SA) monolayers at different initial surface pressures. As expected, due to the negative net charge of the liposome-peptide complex, the higher interaction was found with positive charge monolayers (SA). However, the conjugate was also able to incorporate to zwitterionic and anionic lipids. This behaviour was also confirmed performing compression isotherms of monolayers of these lipids spread on subphases containing the conjugate. These results suggest that the coupling of VP3 (110-121) to liposomes does not influence its ability to interact with membrane lipids such as DPPC and DPPG. Then it can be assumed that its immunogenicity will be preserved or even increased after this modification. All these results are also useful in the preparation of liposome-based synthetic peptide vaccines.
In vivo drug release from solid lipid nanoparticles (SLN) takes place by diffusion and degradation of the lipid matrix. SLN with different degree of crystallinity were prepared to study the effect of crystallinity on the degradation velocity. These SLN were produced by using glycerides with different length of fatty acid chains and known differences in crystallisation velocity (Dynasan 114 and 116), and using stabilisers interfering differently with the crystallisation process of the lipid matrix (cholic acid sodium salt (NaCh), Poloxamer 407 (Plx 407)). NaCh disturbs the crystallisation process, Poloxamer shows little interference. The particles were characterised by photon correlation spectroscopy (PCS) and differential scanning calorimetry (DSC), degradation velocity was determined directly after production and during storage up to 4 weeks under different storage conditions using an especially developed assay based on the NEFA Test kit. After production, SLN with a lower crystallinity matrix (Dynasan 114 and 116, NaCh) degraded faster than higher crystalline particles (all SLN with Plx 407), and showed a decrease in degradation velocity with increasing crystallinity during storage. Fast crystallising particles made from Dynasan 116 stabilised with the non-interfering Plx 407 showed no change in the degradation velocity during storage. SLN produced with a higher crystalline lipid in combination with the crystallisation-disturbing NaCh (Dynasan 116, NaCh) required a 'ripening time' to reach sufficient crystallinity.
With the rapid development of nanotechnology, there is a growing interest on the application of nanoparticles in various fields such as photonics, catalysis, magnetics, and biotechnology including cosmetics, pharmaceutics, and medicines. However, little is known about their potential toxicity to human health. Owing to their special properties, nanoparticles have the capacity to bypass the blood-brain barrier (BBB). However, the toxic effects of nanoparticles on central nervous system (CNS) function are still lacking. And the interactions of nanoparticles with the cells and tissues in CNS are poorly understood. Thus, neurotoxicity induced by nanoparticles is still a new topic that requires more attention. In this review, we summarized the pathways by which the nanoparticles could enter into the CNS and the recent investigations on the neurotoxicity of nanoparticles both in vitro and in vivo, as well as the potential mechanisms. Furthermore, the future direction in the neurotoxicity studies of nanoparticles is also discussed.
The aim of this work was to synthesize [166Dy]Dy/166Ho-DTPA-Biotin to evaluate its potential as a new radiopharmaceutical for targeted radiotherapy. Dysprosium-166 (166Dy) was obtained by neutron irradiation of enriched 164Dy(2)O(3) in a Triga Mark III reactor. The labeling was carried out in aqueous media at pH 8.0 by addition of [166Dy]DyCl(3) to diethylenetriaminepentaacetic-alpha,omega-bis(biocytinamide) (DTPA-Biotin). Radiochemical purity was determined by high-performance liquid chromatography (HPLC) and TLC. The biological integrity of labeled biotin was studied evaluating its avidity for avidin in an agarose column and by size-exclusion HPLC analysis of the radiolabeled DTPA-Biotin with and without the addition of avidin. Stability studies against dilution were carried out by diluting the radiocomplex solution with saline solution and with human serum at 37 degrees C for 24 h. The [166Dy]Dy/166Ho-labeled biotin was obtained with a 99.1+/-0.6% radiochemical purity. In vitro studies demonstrated that [166Dy]Dy/166Ho-DTPA-Biotin is stable after dilution in saline and in human serum and no translocation of the daughter nucleus occurs subsequent to beta(-) decay of 166Dy that could produce release of 166Ho(3+). Avidity of labeled biotin for avidin was not affected by the labeling procedure. Biodistribution studies in normal mice showed that the [166Dy]Dy/166Ho-DTPA-Biotin has a high renal clearance. In conclusion, the radiolabeled biotin prepared in this investigation has adequate properties to work as a stable in vivo generator system for targeted radiotherapy.