Abstract: Solid oral dosage formulations, such as tablet, mini-tab, multiparticulates or osmotic delivery systems, are coated with a mucoadhesive polymeric coating or formed of a mucoadhesive polymer to increase oral bioavailability of Biopharmaceutical Classification System (BCS) Class I drugs. Representative BCS I drugs include valacyclovir, gabapentin, furosemide, levodopa, metformin, and ranitidine HCl. The inclusion of mucoadhesives in the solid oral dosage form brings the dosage form into close proximity with the target epithelium and facilitates diffusion of drug into intestinal tissue. The mucoadhesive polymer may be either dispersed in the matrix of the tablet or applied as a direct compressed coating to the solid oral dosage form. Preferred mucoadhesive polymers include poly(adipic)anhydride “P(AA)” and poly(fumaric-co-sebacic)anhydride “P(FA:SA)”.