Owing to its lack of oral absorption, heparin has to be administered parenterally. However, parental administration has negative aspects such as multiple injections, possible infection, patient inconvenience, and high cost. Now, low molecular weight heparin (LMWH) is taking part in antithrombotic treatment and is proven to confer more advantages than unfractionated heparin. The aim of our present study was to formulate, by the w/o/w emulsification process, LMWH microparticles as potential oral carriers prepared with biodegradable (poly-epsilon-caprolactone and poly-lactic-co-glycolic acid) and nonbiodegradable polycationic polymers (Eudragit RS and RL), used alone or blended. The encapsulation efficiency ranged from 16 to 47% and was highly dependent on the presence of the positively charged polymers. In the same way, a low in vitro LMWH release was observed when Eudragit polymers composed totally or partially the polymeric matrix, compared with biodegradable polymers exhibiting higher LMWH release (40 and 60%). For each formulation, LMWH released from microparticles preserved its biological activity as shown by the antifactor Xa activity. Experiments performed with fluorescein-labeled LMWH showed the drug distribution in microparticles and may give information about the mechanisms controlling LMWH encapsulation and release.
Viable Saccharomyces boulardii, used as a biotherapeutic agent, was encapsulated in food-grade whey protein isolate (WP) and alginate (ALG) microparticles, in order to protect and vehicle them in gastrointestinal environment. Yeast-loaded microparticles with a WP/ALG ratio of 62/38 were produced with high encapsulation efficiency (95%) using an extrusion/cold gelation method and coated with ALG or WP by a simple immersion method. Swelling, yeast survival, WP loss and yeast release in simulated gastric and intestinal fluids (SGF and SIF, pH 1.2 and 7.5) with and without their respective digestive enzymes (pepsin and pancreatin) were investigated. In SGF, ALG network shrinkage limited enzyme diffusion into the WP/ALG matrix. Coated and uncoated WP/ALG microparticles were resistant in SGF even with pepsin. Survival of yeast cells in microparticles was 40% compared to 10% for free yeast cells and was improved to 60% by coating. In SIF, yeast cell release followed coated microparticle swelling with a desirable delay. Coated WP/ALG microparticles appear to have potential as oral delivery systems for Saccharomyces boulardii or as encapsulation means for probiotic cells in pharmaceutical or food processing applications.
Insulin-loaded WP/ALG MP with high quantities of drug entrapped, in vitro matrix swelling and protective effect as well as excellent mucohadesive properties was developped. Improvement of intestinal delivery of insulin and increased in bioavailability were recorded.
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