Abstract

Purpose: This study was conducted to evaluate the permeation of diclofenac acid and its salts from emulgel through rat skin. Methods: Their penetration performances were evaluated using two-chamber side-by-side diffusion cells containing excised rat skin and the drug concentration in the receptor compartment was determined by HPLC. Results: Among the salts examined, diclofenac N-(hydroxyethyl) piperidine (D-HEPP) and diclofenac ethanolamine (D-EA) were found to be the most appropriate form of diclofenac acid to promote drug permeation in our system. The partition coefficient of the drugs between stripped skin and emulgel (K_s) was also determined, and a positive relationship was found between K_s and the cumulative amount of drug permeated over a period of 8 h (Q₈) with a correlation coefficient (r) of 0.974. Statistical analysis using the regression function of the SPSS 11.5 software allowed us to conclude that K_s was a key factor controlling drug permeation and, in the case of the physicochemical properties of the salts, the salt hydrophilicity represented by water solubility (S_w) was a primary factor influencing salt permeation. Conclusion: Diclofenac salts are more suitable for emulgel preparation than diclofenac free acid

Keywords:  Diclofenac salts   Emulgel   Percutaneous absorption   SPSS