BIOADHESIVE MICROSPHERES .3. AN IN-VIVO TRANSIT AND BIOAVAILABILITY STUDY OF DRUG-LOADED ALGINATE AND POLY(FUMARIC-CO-SEBACIC ANHYDRIDE) MICROSPHERES

Bioadhesive drug delivery systems (BDDSs) could improve bioavailabilit y by protecting bioactive molecules from physical and chemical degrada tion, enhancing absorption rates by minimizing diffusion barriers, and increasing the period for absorption by prolonging residence time. Th e in vivo bioadhesive performance of calcium alginate microspheres and poly(fumaric-co-sebacic anhydride) 20:80 microspheres were evaluated in two ways. Firstly, effect on GI transit was measured in rats. P(FA: SA) 20:80 microspheres showed significantly prolonged retention in the gut when compared to alginate microspheres. Secondly, the ability of these polymers to improve relative bioavailability of a model drug, di cumarol, in rats was assayed. A significant increase was measured in t he area under the plasma concentration-time curve for dicumarol encaps ulated in P(FA:SA) 20:80 when compared to its controls. The results of this study suggest that polymers which have bioadhesive forces in vit ro and delayed GI transit in vivo may be used to improve oral bioavail ability of certain drugs. (C) 1997 Elsevier Science B.V.