Evaluation of the transdermal permeation behavior of Proterguride from drug in adhesive matrix patches through hairless mouse skin

The transdermal in vitro permeation behavior of the highly potent dopamine agonist Proterguride was investigated using hairless mouse skin as a model membrane. Drug in adhesive matrix formulations based on different types of pressure-sensitive adhesives (Eudragit® E 100 and Gelva®7883 as acrylates, Oppanol® B 15 SFN as polyisobutylene, and BioPSA® 7-4202 as silicone) with a drug load of 3% by weight were manufactured. All patches were examined for drug crystallization by polarized microscopy immediately after the manufacturing process and after storage for 30 days in sealed aluminium laminate bags at ambient temperature and at 40°C, respectively. Furthermore, the influence of the drug load in acrylate-based formulations onto the steady-state flux of Proterguride was examined. The Eudragit® E 100 system delivered a significantly higher steady-state flux than the systems based on Oppanol® B 15 SFN and also a somewhat higher steady-state flux than the Gelva®-based patch. An addition of 10% by weight of the crystallization inhibitor povidone 25 did not significantly influence the steady-state flux of Proterguride from acrylate matrices. The lipophilic silicone and polyisobutylene adhesives facilitated drug crystallization within the short storage periods at both conditions, probably due to the absence of povidone 25, which was incompatible with these polymers. Varying the drug load in acrylate-based formulations led to a linear increase of the steady-state flux until the steady-state flux of Proterguride leveled off and the patches tended to drug crystallization. It was found that Gelva®-based patches show good physical stability, good skin adhesion, and moderate flux values and, thus, can be evaluated as a basis for a suitable formulation for the transdermal administration of Proterguride.