Fabrication of chitosan–polyacrylic acid complexes as polymeric osmogents for swellable micro/nanoporous osmotic pumps

Abstract

Aim: The aims of this study were to prepare and evaluate chitosan–polyacrylic acid complex (CS-PAA) as polymeric osmogents for swellable micro/nanoporous osmotic pump propranolol tablets.

Methods: The complexes were characterized and evaluated for their swelling characteristics. The selected complexes were incorporated into the core propranolol tablets as polymeric osmogents. The core tablets were formulated, compressed as monolithic and two-layered tablets, and finally coated with cellulose acetate containing PEG 400 and PVP K30 as plasticizers and pore formers, respectively. As a final point, the drug release was determined.

Results: A direct correlation was found between the CS content in the complex and the maximum swelling force and swelling ratio of the complex mixture. In vitro drug release revealed that the percent drug release increased with the amount of osmogent in the two-layered tablets. Drug release could be prolonged up to 12 h and conformed to the USP 31 criteria. In contrast, percent release decreased with the increasing amount of complexes in monolithic tablets. It was postulated that two opposing mechanisms were involved. Following water uptake, the complexes of polymers swelled and pushed the drug out of the tablets, and the drug bound to the polymer network and remained in the tablets.

Conclusions: The results indicated that the complex of CS-PAA at optimal proportion and amount was a promising polymeric osmogent for a zero-order controlled release from two-layered swellable micro/nanoporous osmotic pump tablets.

Keywords::

• Micro/nanoporous semipermeable membrane
• osmotic agent
• chitosan
• polyacrylic acid
• interpolymer complex