Fabrication and evaluation of felodipine push-pull osmotic pump capsule

Felodipine is traditionally delivered as extended-release tablets, but a push-pull osmotic pump (PPOP) capsule represents a promising alternative platform for controlled-release delivery. This work sought to characterize properties of the felodipine drug substance and crosslinked hard gelatin capsules (HGCs) for the preparation of the PPOP capsule. Additionally, drug release profiles of felodipine PPOP capsules under various formulation and medium conditions were investigated. Felodipine drug substances and crosslinked HGCs were evaluated for their physicochemical properties. Moreover, the type of release medium, number of Corelease CA coating rounds, amounts of Polyox WSR N80 and Polyox WSR Coagulant, sodium chloride content, and source of the drug substance were studied. Results showed that the physicochemical properties of felodipine drug substances exhibited statistically significant but minor variations between the two sources. Crosslinked HGCs remained insoluble in all tested media and exhibited spectral changes consistent with formaldehyde-induced crosslinking. Drug release approached Higuchi's kinetics when the formulation comprised 10 mg felodipine from a specific manufacturer, 120 mg of Polyox WSR N80, 35 mg of Polyox WSR Coagulant, and 20 mg of sodium chloride, with 10 coating rounds of Corelease CA and 1% sodium lauryl sulfate as the release medium. In conclusion, these findings highlight the significant influence of formulation parameters on drug-release behavior and provide a basis for developing PPOP capsules with consistent and predictable performance.