Analgesic Action of Amfenac Na a Non-steroidal Anti-inflammatory Agent

Abstract

Amfenac Na is a new non-steroidal analgesic anti-inflammatory drug which is clinically used for ailments such as rheumatoid arthritis and pain and/or inflamation after surgery. In this paper, amfenac Na is studied on the bradykinin induced-flexor reflex and the simultaneous recording of the cortical somatosensory-evoked response (SER) and the electromyogram of digastric muscle (d-EMG) evoked by a tooth pulp stimulatio n. Amfenac Na at doses of 0.1 - 1 mg/kg p. osuppressed hindlimb flexor reflexes induced by bradykinin infusion in the rat. This effect was the most potent among the drugs used; the order of potency was as follows: amfenac Na floctafenine > loxoprofen >> piroxicam = emorfazone > mefenamic acid. Similarly the intravenous injection of amfenac Na completely suppressed the flexor reflex with a dose as low as 0.1 mg/kg; the potency was almost equal to that of morphin e. On the SER and d-EMG evoked by tooth pulp stimulation a high dose (100 mg/kg i.v.) of amfenac Na showed very weak inhibition, whereas morphine (10 mg/kg i.v.) suppressed those response s. These data suggest that amfenac Na showed a very potent analgesic effect comparable to morphine, and that the site of action is mainly the periphery. © 1988, The Pharmaceutical Society of Japan. All rights reserved.