BRL 20459, a novel topically active non-steroidal anti-inflammatory drug

Anti-inflammatory pharmacology and mechanism of the orally active capsaicin analogs, NE-19550 and NE-28345

We have evaluated the properties of a new class of anti-inflammatory agents derived from capsaicin, using the analogs NE-19550 (N-vanillyloleamide) and NE-28345 (N-oleyl-homovanillamide) as examples. This class displayed an atypical profile in the assays utilized, including 1) anti-edema and antileukocyte migration activity in the rat carrageenan pleurisy assay without suppression of pleural prostanoid synthesis, 2) blockade of human platelet aggregation induced by arachidonate or PAF but not that induced by the PGH2 analog U-46619, without equivalent inhibition in vitro of mammalian cyclooxygenase or thromboxane synthetase preparations, 3) greater potency and efficacy in the rat implanted sponge assay than in the adjuvant arthritis assay, without inhibition of LTB4 or 15-HETE synthesis in vitro, 4) stronger topical activity in the mouse croton oil inflamed ear assay than the guinea pig UV erythema assay, and 5) oral activity in the rat carrageenan paw edema assay and mouse phenylquinone abdominal constriction rest combined with failure to induce gastric erosion in rats at therapeutic doses. We conclude that NE-19550 and NE-28345 do not act like conventional NSAIDs via suppression of arachidonic acid metabolism.

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

Bromfenac [2-amino-3-(4-bromobenzoyl)benzeneacetic acid sodium salt 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 activity in the acetylcholine-induced abdominal constriction test in mice. In this test, bromfenac was more potent than indomethacin (24.9X), more potent than ketoprofen (approximately 14.9X), and superior to piroxicam. In the guinea pig UV-erythema test, bromfenac was active (26.1X 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.