title: In vitro evaluation of topical microemulsion of capsaicin free of surfactant.
abstract: Topical microemulsion of capsaicin without surfactant was developed in this study. In these systems, the oil phase was benzyl alcohol, and the cosurfactant was propylene glycol and ethanol. The drop-size of the systems was measured by dynamic light scattering method in order to distinguish true solution from microemulsion. The transdermal performance of the microemulsions was evaluated in vitro by Franz diffusion cells fitted with rat skins. The results showed the drop-size of the microemulsions without surfactant was smaller than that of the systems with Tween 80 and the permeation rate of capsaicin decreased as the content of Tween 80 increased. In the system composed of water, benzyl alcohol and propylene glycol, the permeation rate increased with the enhancement of benzyl alcohol and water. But water content had little effect on the permeation rate in the microemulsions with ethanol as cosurfactant.
authors.affiliation: School of Pharmaceutical Science and Technology, Tianjin University, PR China.
authors.forename: Pengwei
authors.initials: P
authors.lastname: Zhang
authors.forename: Wenyuan
authors.initials: W
authors.lastname: Gao
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Li
authors.initials: L
authors.lastname: Chen
authors.forename: Qufei
authors.initials: Q
authors.lastname: Shen
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Wang
authors.forename: Ying
authors.initials: Y
authors.lastname: Cui
mesh_terms: D000818:Animals; D019905:Benzyl Alcohol / Q000737:chemistry / Q000494:pharmacology; D002211:Capsaicin / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics*; D002626:Chemistry, Pharmaceutical; D002851:Chromatography, High Pressure Liquid; D004355:Drug Stability; D004655:Emulsions; D000431:Ethanol / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D010316:Particle Size; D010592:Pharmaceutic Aids / Q000737:chemistry / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012869:Skin Absorption / Q000187:drug effects; D013500:Surface Tension; D013501:Surface-Active Agents
chemical_list: D004655:Emulsions; D010592:Pharmaceutic Aids; D013501:Surface-Active Agents; D000431:Ethanol; D019905:Benzyl Alcohol; D002211:Capsaicin