title: Skin permeation enhancement of diclofenac by fatty acids.
abstract: This study systematically investigated the enhancing effect of fatty acids on the skin permeation of diclofenac. The fatty acids were evaluated in terms of their carbon-chain length, the degree of unsaturation, and their functional groups. The rat-skin permeation rates of diclofenac, saturated in propylene glycol (PG) containing 1% (w/v) fatty acid, were determined using the Keshary-Chien diffusion cells at 37 degrees C. The effect of fatty acids on the saturated solubility of diclofenac in PG was also determined at 37 degrees C using high-performance liquid chromatography. Among the saturated fatty acids tested, palmitic acid (C16:0) showed the most potent skin permeation-enhancing effect. A parabolic correlation was observed between the enhancement effect and the fatty acid carbon-chain length among these saturated fatty acids of C12-C20 units. For the monounsaturated fatty acid series, an increase in permeation was observed as the carbon-chain length increased, and oleic acid (C18:1) showed the highest permeation-enhancing effect. Increasing the number of double bonds in the octadecanoic acids resulted in a parabolic effect in the permeation of diclofenac, revealing oleic acid as the most effective enhancer used in this study. When the carboxylic acid moiety of oleic acid was changed to an amide (oleamide) or hydroxyl (oleyl alcohol) group, a decrease in permeation activity was observed. These results, therefore, suggest that the cis-monounsaturated configuration and the carboxylic acid moiety of an 18-carbon unit fatty acid in PG are the optimum requirements for the effective skin permeation of diclofenac.
authors.affiliation: College of Pharmacy, Pusan National University, Busan, South Korea.
authors.forename: Min-Jung
authors.initials: MJ
authors.lastname: Kim
authors.forename: Hea-Jeong
authors.initials: HJ
authors.lastname: Doh
authors.forename: Min-Koo
authors.initials: MK
authors.lastname: Choi
authors.forename: Suk-Jae
authors.initials: SJ
authors.lastname: Chung
authors.forename: Chang-Koo
authors.initials: CK
authors.lastname: Shim
authors.forename: Dae-Duk
authors.initials: DD
authors.lastname: Kim
authors.forename: Jung Sun
authors.initials: JS
authors.lastname: Kim
authors.forename: Chul-Soon
authors.initials: CS
authors.lastname: Yong
authors.forename: Han-Gon
authors.initials: HG
authors.lastname: Choi
mesh_terms: D000277:Adjuvants, Pharmaceutic / Q000737:chemistry / Q000494:pharmacology*; D000279:Administration, Cutaneous; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry / Q000493:pharmacokinetics*; D002851:Chromatography, High Pressure Liquid; D004008:Diclofenac / Q000737:chemistry / Q000493:pharmacokinetics*; D016503:Drug Delivery Systems; D004353:Drug Evaluation, Preclinical; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D010539:Permeability; D051381:Rats; D017207:Rats, Sprague-Dawley; D012867:Skin / Q000187:drug effects / Q000378:metabolism; D012869:Skin Absorption / Q000187:drug effects*; D012995:Solubility; D013329:Structure-Activity Relationship
chemical_list: D000277:Adjuvants, Pharmaceutic; D000894:Anti-Inflammatory Agents, Non-Steroidal; D005231:Fatty Acids, Unsaturated; D004008:Diclofenac