Preformulation studies of melanotan-II

Abstract

Melanotan-II (MT-II) is a cyclic heptapeptide analogue of α-MSH (α-melanocyte stimulating hormone) which tans the skin rapidly and is currently being evaluated for the prevention of sunlight-induced skin cancers. In these preformulation studies, the degradation of MT-II followed apparent first-order kinetics. The degradation rate increased as the temperature or phosphate buffer concentration were increased. The pH-rate profile of MT-II degradation showed that MT-II was most stable at approximately pH 5. The degradation of MT-II was not affected by ionic strength. The pKa1 and pKa2 were estimated to be 6.53 and 11.74, respectively. The partition coefficient was studied at various pH values. The Δ log PC at pH 7.35 was 1.05 which indicated that MT-II could pass the intestinal membrane relatively easily. The preformulation data presented here can be used to help develop an appropriate dosage form for MT-II.