The effect of enhancer on the penetration of oxybutynin chloride via transdermal drug delivery

The transdermal therapeutic system(TTS) of oxybutynin chloride has various advantages over it oral dosage forms. The ideal oxybutynin chloride TTS requires high skin permeation rate in short time after it is applied on the skin. The skin permeation rate of oxybutynin chloride from various skin enhancers were determined using Franz diffusion cells fitted with excised rat skins. Among fatty acid studied, oleic aicd was the most effective enhancer, which increased the permeability of oxybutynin chloride approximately 4.03-fold compared with the control without penetration enhancer. Because short-chain fatty acids have insufficient lipophilicity for skin penetration, while long-chain fatty acids have a much higher affinity to lipid in the stratum corneum. Lauryl alcohol increased the permeability of oxybutynin chloride approximately 3.08-fold compared with the control. Among terpene studied, limonene was the most effective enhancer, which increased the permeability of oxybutynin chloride approximately 2.56-fold compared with the control. The number of carbonyl groups in Enhancer's ring has important effect on enhancing activity because the increase of carbonyl groups in the ring causes a permeability decrease.