The topical anti-inflammatory and analgesic properties of bromfenac in rodents

Bromfenac [2-amino-3-(4-bromobenzoyl) benzeneacetic acid sodium slat sesquihydrate] is an anti-inflammatory/analgesic agent that possesses potent topical activity in rats, guinea pigs, and mice. In rat models of acute (carrageenan paw edema) and chronic (adjuvant arthritis) inflammation, preparations of bromfenac at concentrations as low as 0.01–0.32% (0.01–0.32 mg bromfenac) produced significant anti-inflammatory activity when applied to the injected paw or to the backs of rats. In the acute paw edema test, topical bromfenac was more potent than indomethacin or hydrocortisone and about as active as triamcinolone acetonide. Bromfenac, at concentrations of 0.1–0.32%, showed topical analgesic more potent than indomethacin (24.9×), more potent than ketoprofen (14.9×), and superior to piroxicam. In the guinea pig UV-erythema test, bromfenac was active (26.1×indomethacin) when applied to the UV-exposed site, but not when applied away from the site. The results suggest that bromfenac has activity topically because of a local and a systemic effect. Test results obtained with a long (4–7 hr) pretreatment time (paw edema, adjuvant arthritis, abdominal constriction) are due in great part to a systemic effect of topically applied bromfenac, while the UV-erythema test (1-hr treatment time) clearly indicates a local effect.