Transdermal behaviors comparisons among Evodia rutaecarpa extracts with different purity of evodiamine and rutaecarpine and the effect of topical formulation in vivo.

Evodiamine (EVO) and rutaecapine (RUT), the major active components from Evodia rutaecarpa extract (EE), are recognized as a depended analgesic agent. This study was designed to investigate the effect of purity and chemical enhancers on the transdermal behavior of EVO and RUT, and the pharmacological effect of their topical cream in vivo. Transdermal delivery across a full thickness pig abdominal skin was detected in vitro by Franz-type diffusion cell, with HPLC for quantification of the permeation of EVO and RUT. The activity of topical cream in vivo was evaluated by a mice pain model induced by formalin and hot plate. Transdermal characters of EVO and RUT showed a low transdermal rate, long lag time and low cumulative amount. The transdermal rate and cumulative amount could be promoted by lipophilic enhancers, whereas lag time was shortened by hydrophilic surfactant, but these permeation parameters were not markedly influenced by purity of EE (p>0.05). The effect in vivo was confirmed by analgesic models in topical cream of EE, which produced a significant (p<0.05) inhibitory effects on pain response in dose-dependent manner. The purity of EVO and RUT from EE has no significant effect on their permeation through porcine skin, but oleic acid or nerolidol can markedly elevate the transdermal rate of EVO and RUT. High purity of EE is the best choice for topical preparation to increase the drug loading. The effect of EE in vivo is verified by formalin model and hot plate test.