Assessment of topical non-steroidal anti-inflammatory drugs in animal models

Four commercial gel preparations of topical anti-inflammatory agents have been assessed in six animal models commonly used to determine the biological activity of non-steroidal anti-inflammatory agents for systemic administration. Only UV-induced erythema of the skin, adjuvant induced arthritis and the measurement of vascular permeability proved suitable for differentiation of the potency of the four topical agents. Carrageenin-induced paw oedema, the cotton pellet test and the assessment of the pain threshold according to Randall and Selitto were of little value. The effects of the gel preparation of diclofenac (CAS 15307-86-5) diethylammonium (Voltaren Emulgel) were comparable to two preparations containing 1% and 5% active ingredient, respectively. Gel 4 showed low overall activity. The experiments demonstrated that some of the models used for the assessment of anti-inflammatory agent for systemic administration proved suitable for the testing of topical preparations and that percutaneous absorption was insufficient to elicit anti-inflammatory effect in the animals at sites remote from the site of application.