Anti-inflammatory and analgesic activities of a trans-cutaneous non-steroidal anti-inflammatory agent, etofenamate gel, in experimental animals

Abstract

Anti-inflammatory and analgesic activities of topically applied etofenamate gel (5% etofenamate) were investigated in experimental animals. Etofenamate gel showed a dose related inhibition against vascular permeability caused by histamine in mice and ultra violet light-induced erythema in guinea pigs at doses of 10-100 mg/site and 25-200 (ED50=26.6) mg/site, respectively. The erythema was not inhibited with its topical application of 100 mg/site to the skin distant from the erythema. Granuloma formation, caused by felt-pellet implantation, was inhibited in a dose dependent manner by repeated application of etofenamate gel (10-100 mg/site/day). Etofenamate gel inhibited the pain-like responses in both the arthritic joint and the edematous hind paw of rats with 50-200 mg/joint and 100 mg/paw, respectively. In these tests, the vehicle gel did not show any significant activity. The potency of etofenamate gel was stronger than that of adrenal-extracts ointment (Mobilat) and approximately comparable to indomethacin ointment (1% indomethacin) in a weight basis of formulations. Topical application of etofenamate (0.5-2 mg/ear) resulted in a dose related decrease of contact hypersensitivity to oxazolone in mice, and its activity was nearly equipotent to flufenamic acid and about one-fourth that of indomethacin. From these results, it was suggested that etofenamate gel, applied topically to the inflamed tissue, showed a certain inhibitory activity against acute and subacute-chronic inflammation and inflammatory pain-like responses.