Comparison of analgesic and anti-inflammatory activity of meloxicam gel with diclofenac and piroxicam gels in animal models: pharmacokinetic parameters after topical application

Abstract

Meloxicam, a non-steroidal anti-inflammatory drug, is a preferential inhibitor of cyclooxygenase-2 and has demonstrated potent analgesic and anti-inflammatory activity after oral administration. The present work was carried out to elucidate the anti-inflammatory and analgesic activity of a newer topical gel formulation of meloxicam (1% w/w gel) and compare it with 0.5% w/w piroxicam and 1% w/w diclofenac gels in experimental animal models. The study was also extended to determine the pharmacokinetic profile of a newer formulation of meloxicam gel after topical application on depilated skin of rats. The anti-inflammatory activities of meloxicam, piroxicam and diclofenac gels were compared using carrageenan-induced acute paw oedema and complete Freund's adjuvant-induced chronic paw oedema in rats. Meloxicam gel showed increased protection against inflammation as compared to piroxicam and diclofenac gels. Acetic acid-induced writhing and formalin-induced phase I and phase II pain models were used to compare their analgesic activity. Meloxicam gel showed significant protection in formalin-induced phase II pain whereas its analgesic activity was less as compared to diclofenac and piroxicam gels in writhing test and formalin-induced phase I pain. The pharmacokinetic studies showed peak plasma drug concentration (C(max)) of 48.48 +/- 6.57 microg/ml at 2 h (T(max)) after topical application of 500 mg of meloxicam gel formulation. The area under the curve as calculated from 0 to 6 h was found to be 114.18 +/- 4.23 and 194.13 +/- 3.78 microg x h/ml for 0 to infinity. The results indicate that topical preparation of meloxicam could be an effective alternative to diclofenac and piroxicam gels in inflammatory conditions and its associated pain with the possibility of less systemic side-effects.