title: Transdermal delivery of capsaicin derivative-sodium nonivamide acetate using microemulsions as vehicles.
abstract: The objective of this study was to prepare sodium nonivamide acetate (SNA) microemulsion for topical administration. Microemulsions consisted of a mixed surfactant of Tween 80 and Span 20 as surfactant, ethanol as cosurfactant, isopropyl myristate (IPM) as an oil phase and water as an external phase. The effect of composition of microemulsion including the ratio of oil phase/surfactant/aqueous phase, various cosurfactant and polymer on the character and permeability of microemulsion were evaluated. The mean droplet size of SNA microemulsions ranged from 64 to 208 nm. Microemulsions showed potent enhancement effect for SNA transdermal delivery by a 3.7-7.1-fold increase when compared with the control group. Microemulsion containing ethanol as cosurfactant had the highest enhancement effect. With incorporated polymer, the viscosity of microemulsions increased resulting in the decrease in penetration rate of SNA. However, the permeability of SNA delivered from microemulsion was higher than SNA from volatile vehicles (pH 4.2 buffer containing 25% ethanol) reported in an earlier study, therefore microemulsions could be an effective vehicle for topical delivery of SNA.
authors.affiliation: Graduate Institute of Clinical Pharmacy, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung City 80708, Taiwan.
authors.forename: Yaw Bin
authors.initials: YB
authors.lastname: Huang
authors.forename: Yong Hao
authors.initials: YH
authors.lastname: Lin
authors.forename: Tzy Ming
authors.initials: TM
authors.lastname: Lu
authors.forename: Ren Jiunn
authors.initials: RJ
authors.lastname: Wang
authors.forename: Yi Hung
authors.initials: YH
authors.lastname: Tsai
authors.forename: Pao Chu
authors.initials: PC
authors.lastname: Wu
mesh_terms: D000279:Administration, Cutaneous; D000818:Animals; D002211:Capsaicin / Q000008:administration & dosage / Q000031:analogs & derivatives*; D004553:Electric Conductivity; D004655:Emulsions; D066298:In Vitro Techniques; D010316:Particle Size; D014677:Pharmaceutical Vehicles; D051381:Rats; D012869:Skin Absorption; D013501:Surface-Active Agents; D014783:Viscosity
chemical_list: D004655:Emulsions; D014677:Pharmaceutical Vehicles; D013501:Surface-Active Agents; D002211:Capsaicin; C040937:nonivamide