Zeitschrift für Arzneimittelentwicklung
Offener Zugang

Abstrakt

Comparison of the Topical Analgesic Effects of a Novel Diclofenac Microemulsion to a Marketed Diclofenac Macroemulsion Formulation in Rats Using the Tail Flick Test

Tarique Benbow and Jacqueline Campbell

Current topical preparations do not provide optimal topical drug delivery. Microemulsions have been proposed to increase drug penetration across the skin, leading to increased bioavailability and efficacy of the drug product. This study compares the topical analgesic effects of novel diclofenac diethylamine (DDEA) water-in-oil (w/o) microemulsion to a marketed diclofenac diethylamine (DDEA) oil-in-water (o/w) macroemulsion (Voltaren Emulgel ^®) in the treatment of acute thermal pain using the rat tail flick test. Eighteen (N=18) Sprague-Dawley rats were divided into three (3) groups (n=6). The groups were administered the novel microemulsion of DDEA (test group), the marketed macroemulsion of diclofenac (positive control group) and the microemulsion alone (negative control group); the rat tail flick test was performed after topical administration to assess analgesia observed. Mean maximum possible effect (MPE) in percentage was calculated for each group and analyzed using the one-way ANOVA for statistical significance (p<0.05) across the groups. The group administered the DDEA o/w microemulsion had the numerical highest MPE (27.459 ± 7.849%). This was statistically significant (p<0.05) when compared to negative control group but was not statistically significant (p>0.05) when compared to the positive control group. Further studies that specify the mechanism(s) and address limitations are needed to expand these findings to clinical applications.