Formulation study of a transdermal delivery system of primaquine

A potential transdermal application of an anti-malarial drug, primaquine, was investigated. In-vitro percutaneous absorption through hairless rat skin using either the salt or free base form of this drug was studied. Investigations were performed in order to choose an adequate vehicle for transdermal delivery of the free base form. The vehicles studied were Mygliol(R) 840 (M), Labrafac Hydrophile(R) (LH), Transcutol(R) (T), propylene glycol (PG), oleic acid (OA) and a mixture LH/T 50:50. Finally, transdermal release of primaquine from different matrix transdermal therapeutic systems (TTS) was compared. In this optimization we studied the influence of polymer type (Eudragit(R) RL 100 or ethyl cellulose), adhesive layer and drug concentration in the polymeric matrix on the release profiles. Primaquine free base was found to be very suitable for transdermal delivery. Mygliol(R) 840 showed the best enhancement factor of the percutaneous flux of primaquine. The optimized TTS, which was an ethyl cellulose-based formulation with Mygliol(R) 840 as vehicle, showed a percutaneous flux of 180 mu g cm(-2) h(-1).