Oral anticoagulant therapy with heparin has been challenged by formulating heparin in oral solid preparation. As heparin, low molecular weight heparin (LMWH) was used. LMWH was dispersed with a surfactant used for the self-microemulsifying drug delivery system (SMEDDS), PEG-8 caprylic/capric glycerides (Labrasol), and the mixture was solidified with three kinds of adsorbents, microporous calcium silicate (Florite RE), magnesium alminometa silicate (Neusilin US(2)) and silicon dioxide (Sylysia 320). The in vitro release study showed that the T50%s were 3.2+/-0.1min for Sylysia 320, 4.6+/-0.2min for Florite RE, 13.7+/-0.1min for Neusilin US(2). The in vivo rat absorption study showed that Florite RE system had the highest C(max), 0.42+/-0.01IU/mL and AUC, 0.59+/-0.06IUh/mL, where plasma LMWH levels were measured as anti-Xa activity. Other preparations had the C(max) and AUC, 0.12+/-0.01IU/mL and 0.15+/-0.02IUh/mL for Neusilin US(2) and 0.25+/-0.02IU/mL and 0.40+/-0.03IUh/mL for Sylysia 320, respectively. The bioavailability (BA) of LMWH from the microporous calcium silicate preparation, Florite RE, was 18.8% in rats by comparing the AUC obtained after i.v. injection of LMWH, 40IU/kg to another group of rats. Florite RE system was evaluated in dogs after oral administration in an enteric capsule made of Eudragit S100 at the LMWH dose of 200IU/kg. High plasma anti-Xa activity levels were obtained, i.e., the C(max) was 0.48+/-0.11IU/mL and AUC was 1.64+/-0.32IUh/mL. These results suggest that adsorbent system is useful as an oral solid delivery system of poorly absorbable drugs such as LMWH.
[Show abstract][Hide abstract] ABSTRACT: Advances in biotechnology, gene manipulation, and protein engineering for macromolecule drugs, such as insulin, parathyroid
hormone (PTH), calcitonin, human growth hormone, erythropoietin (EPO), and peptide YY (PYY) allow commercial production in
large scale for diverse therapeutic uses. Other macromolecules, such as mucopolysaccharide heparin, have expanded markets
through improvements in their pharmacokinetic and pharmacological effects. However, most products are available only as injectable
forms and are limited to patients with no alternative therapeutic choices. Orally available macromolecule formulations are
still unmet needs for improving patient compliance and expanding administration paradigms and indications. Oral delivery technologies
including carrier systems, absorption enhancers, protease inhibitors, and modification by conjugating transporter or receptor
recognition molecules have been developed and some are undergoing clinical studies. In this review, we discuss major obstacles
for oral absorption of macromolecule drugs and summarize recent strategies to overcome the huddles related to enhancing intestinal
[Show abstract][Hide abstract] ABSTRACT: Microemulsions are potentially excellent carriers for bioactive molecules. They offer the advantage of spontaneous formation, ease of manufacture, thermodynamic stability, and improved solubilization of bioactive materials. This review explores some of the new trends in microemulsion research through analysis of some representative studies. The solubilization of different classic drugs, peptides, and nutraceuticals in various oral microemulsion compositions and microstructures was reviewed. It was found that even W/O microemulsions, which are expected to break upon dilution in the digestive tract, increase the permeability and bioavailability of drugs. Thus, it seems that component selection (the use of molecules that can act as permeability enhancers) is of great importance. Structures such as self-microemulsifying drug delivery systems (SMEDDS), W/O, bicontinuous, and O/W microemulsions, were closely examined, and their potential to serve as drug carriers was evaluated. It seems that for microemulsion systems to be used as vehicles for bioactive materials, the formulations should be based on SMEEDS, which form O/W upon dilution to a specific water content. U-type microemulsions are actually an improved SMEDDS formulation, capable of being diluted with any given water concentration. Much research is being conducted on microemulsion microstructure since there is an obvious direct connection between the microstructure, solubilization capacity, and bioavailability of the active molecules.
Advances in Colloid and Interface Science 01/2007; 128-130:47-64. DOI:10.1016/j.cis.2006.11.016 · 7.78 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Microparticles-adsorbed insulin and zinc insulin (PenfilN) were molded to self-dissolving micropiles (SDMPs) with chondroitin sulfate as the base for the percutaneous administration of insulin. Porous silicon dioxide (Sylysia 320, 440 and 730) and porous calcium silicate (FloriteRE) were used as microparticles. As a reference, insulin loaded SDMPs were prepared. SDMPs were percutaneously administered to mice at the insulin dose level of 2.5 IU/kg. After the insertion of SDMPs to mouse skin, blood samples were collected for 8 h and plasma glucose levels were measured. There were not significant differences on minimum plasma glucose levels between the test preparations. However, T(mins), the time when the minimum glucose level appeared were 1.5 +/- 0.2 h (Sylysia 320), 1.3 +/- 0.2 h (Sylysia 440), 1.6 +/- 0.4 h (Sylysia 730), 2.1 +/- 0.3 h (Florite) and 1.7 +/- 0.3 h (zinc insulin) which were greater than insulin SDMP, 0.8 +/- 0.1 h. In addition, greater hypoglycemic effects were observed with SDMPs containing adsorbent-insulin and/or zinc insulin than insulin SDMP. The mean AACs (area above the plasma glucose level vs. time curve) of SDMPs containing adsorbent-insulin and zinc insulin were 357.8% h for FloriteRE, 333.1% h for Sylysia 320, 308.1% h for Sylysia 440, 328.1% h for Sylysia 730, and 374.7% h for zinc insulin, respectively, which were about two folds higher than that of insulin SDMN, 161.2% h. Those results suggest the usefulness of SDMPs composed of adsorbent-insulin as a long-acting percutaneous insulin preparation.
Journal of Drug Targeting 07/2007; 15(5):323-6. DOI:10.1080/10611860701349794 · 2.74 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.