Abstract: The permeation of melatonin (MT) through the full-thickness mouse skin treated with penetration enhancers such as laurocapram (AZ), oleic acid (OA) and propylene glycol (PG),and/or iontophoresis under the condition with Ag/AgCl or Pt electrode at a current density of 0. 19 mA/cm², frequency of 2000 Hz and on/off ratio of 1:1 was conducted. MT as an unionized lipophilic drug could permeate through full-thickness mouse skin, whose steady-state flux and permeation coefficient were 1.622×10^-3 μg/cm²·s and 0.888×10^-6 cm/s, respectively. Penetration enhancers including 100% AZ, 5% AZ/PG and 10% OA/PG increased the steady-state flux of MT to 7.61, 7.03and 2.98 times compared with that through untreated skin, respectively. The flux of MT was enhanced by current application with Ag electrode with an enhancement factor of 2.19. These results showed that penetration enhancer AZ, OA and/or iontophoresis could enhance the skin permeation of MT.

Key words: Melatonin, Penetration enhancer, Iontophoresis, Permeation