- Effect of rubbing on the in vitro skin permeation of diclofenac-diethylamine 1.16% gel.
Effect of rubbing on the in vitro skin permeation of diclofenac-diethylamine 1.16% gel.
Rubbing a topical NSAID (non steroidal anti-inflammatory drug) on the skin may increase local drug permeation, affecting its distribution to the site of pain and inflammation. The present study evaluates this hypothesis, by assessing in vitro the effect on skin permeation of applying diclofenac-dieythylamine 1.16% gel with or without rubbing. A single dose of 5โmg/cm2 diclofenac-diethylamine 1.16% gel was applied on excised human skin mounted in Franz-type diffusion cells without or with rubbing for 45โs. Drug penetration into the skin layers was determined after 1โh using the tape stripping technique. In vitro cutaneous permeation into the receptor fluid of the diffusion chamber was measured up to 24โh. Skin electrical resistance was also recorded. Application of diclofenac-diethylamine 1.16% gel with rubbing resulted to a 5-fold higher flux of diclofenac through the skin than when applied without rubbing at 8โh (Pโ=โ0.04). Skin rubbing for 45โs decreased by 2-fold skin electrical resistance when compared to the standard application. Application of diclofenac-diethylamine 1.16% gel with rubbing tended to result in higher accumulation in the stripped skin vs. the superficial skin layers when applied without rubbing (Pโ=โ0.2). These results suggest that rubbing may alter the superficial skin layer resulting in a transient faster initial diffusion of topically applied diclofenac through the stratum corneum into the deeper skin layer of the dermis to the tissue target.