Release of Ropinirole from Acrylate-Vinylacetate Transdermal Formulations: Modulation Based on Polymer-Drug Interactions

Optimization of transdermal formulations requires solving simultaneous challenges as the selection of release polymers. The interactions between the formulation components must be taken as a way to modulate its performance. Selection of acrylic polymers with different functionalizations for the transdermal formulation of a tertiary amine drug (ropinirole HCl) have been investigated. Aim of this work is to characterize the influence over drug release of certain experimental interactions. Solubility-crystalization and pharmacopoeial release tests have been used to evaluate the influence of drug loading and the pH of the release media. Area under the curve of dissolved amounts and percentage of release have been used as discriminant variables in mutual influence with the physical state of the drug. Elucidation of release mechanisms has been performed with data fitting of relevant modelystic equations. Fickian release and erosion contribution have been related with drug loading and the risk of burst effects. In conclusion, a rationale to select the best suitable polymer for ropinirole HCl has been demonstrated in terms of efficiency and extent of release.