Percutaneous absorption of diclofenac acid and its salts from emulgel

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 (Ks) was also determined, and a positive relationship was found between Ks 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 Ks 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 (Sw) 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