Percutaneous absorption and model membrane variations of melatonin in aqueous-based propylene glycol and 2-hydroxypropyl-β-cyclodextrin vehicles

Percutaneous absorption and model membrane variations of melatonin (MT) in aqueous-based propylene glycol and 2-hydroxypropyl-β-cyclodextrin vehicles were investigated. The excised hairless mouse skin (HMS) and two synthetic ethylene vinyl acetate (EVA) and microporous polyethylene (MPE) were selected as a model membrane. The solubility of MT was determined by phase equilibrium study. The vertical Franz® type cell was used for diffusion study. The concentration of MT was determined using reverse phase HPLC system. The MT solubility was the highest in a mixture of PG and 2-HPβCD. The percutaneous absorption of MT through excised HMS increased as the solubility increased. However, the permeability coefficient decreased and then slightly increased in a mixture of PG and 2-HPβCD. On the other hand, both flux and permeability coefficient through EVA membrane decreased as the solubility increased. No MT was detected over 12 h after starting diffusion through MPE membrane. The flux of MT was dependent on the type of membrane selected. Flux of MT was greatest in excised HMS followed by EVA and MPE membrane. Flux of MT through EVA membrane was 5-20 times lower when compared to excised HMS. Interestingly, volumes of donor phase when MPE membrane was used, significantly increased during the study period. The HMS might be applicable to expect plasma concentration of MT in human subjects based on flux and pharmacokinetic parameters as studied previously. The current studies may be applied to deliver MT transdermally using aqueous-based vehicles and to fabricate MT dosage forms.