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Evaluation of the New Polyvinylacetate/ Povidone Excipient for Matrix Sustained Release Dosage Forms

Elena Draganoiu, Mahalaxmi Andheria, and Adel Sakr

Industrial Pharmacy Program, College of Pharmacy, University of Cincinnati, Cincinnati, Ohio (USA)

The present research work was designed to evaluate the properties of the new polyvinylacetate/povidone based polymer as a matrix sustained release excipient for a water-soluble drug. A full factorial design at five different concentration levels was applied using propranolol hydrochloride as a model drug and matrix tablets manufactured by direct compression and wet granulation methods. The effects of varying polymer content, method of manufacturing, addition of external binders and influence of pH of dissolution media were characterized by comparing the drug release rate profiles from the tablets. The similarities in release profiles were evaluated by applying the model independent approach using similarity factor f₂. The results obtained showed square root of time dependent Higuchian release kinetics for tablets containing 30-50 % of polymer content, thus indicating a diffusion controlled release mechanism. Also, drug release profiles, at higher polymer levels, from tablets manufactured by direct compression and wet granulation methods were remarkably different. Overall, reproducible and pH independent sustained drug release rates could be achieved successfully by incorporating this new polyvinylacetate/povidone based polymer excipient in matrix tablet dosage forms.

Key Words Drug release kinetics · Matrix sustained release tablets · Polymer excipients · Polyvinylacetate/povidone · Propranolol hydrochloride