Abstract
The transdermal delivery of dihydroergotamine (DHE), from propylene glycol formulations with and without 6.0% laurocapram (Azone), and the penetration enhancing effect of Azone were evaluated in vitro on excised rabbit, rat, hairless mouse, guinea pig and human skins utilizing improved Franz diffusion cells. The steady-state flux of DHE from the propylene glycol formulation without Azone were 0.045, 0.270, 0.395, 0.128 and 10.035 μg/cm
2 per h across excised human, rat, guinea pig, rabbit and hairless mouse, respectively. Under the influence of the enhancer, Azone increased DHE penetration through excised skin of the various species used in this study in the following order: rabbit skin > human skin > rat skin > guinea pig skin > hairless mouse skin. The maximum enhancement factor of Azone (251.47) was obtained across rabbit skin and the minimum enhancing effect (14.44) was observed in the case of hairless mouse skin. The enhancement factor of Azone across human skin was 54.56. These results show that animal skins are poor models for human skin under the conditions used. The lag time of DHE, from the propylene glycol formulation containing 6.0% Azone, through human skin was longer than the lag times across all other skin species tested in this investigation.