Reserpine-induced changes in anesthetic action of fentanyl.
The effect of prior administration of reserpine on fentanyl dose-response curves for loss of the righting reflex and prevention of purposeful movement response to noxious stimulation was studied in rats. It was found that reserpine (5 mg X kg-1, 3 h before the tests) antagonized the effect of fentanyl on purposeful movement response to the tail clamp and, at the same time, strengthened its effect on the righting reflex. As a result, reserpine pretreatment reversed the order of fentanyl potency regarding these two effects. Reserpine changed fentanyl ED50 values for the purposeful movement response from 8.2 to 20.3 micrograms X kg-1 (P less than 0.0001) and for the righting reflex from 20.5 to 13.7 micrograms X kg-1 (P less than 0.0001). The results suggest that reserpine dissociates the analgesic action of fentanyl from its anesthetic action, defined as a loss of the righting reflex. This may be regarded as an indication that the analgesic action of narcotics may not adequately reflect their anesthetic potency.
D000700:Analgesics; D000777:Anesthetics; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005283:Fentanyl / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008297:Male; D009068:Movement / Q000187:drug effects; D004856:Postural Balance / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D012018:Reflex / Q000187:drug effects; D012110:Reserpine / Q000494:pharmacology*
D000700:Analgesics; D000777:Anesthetics; D012110:Reserpine; D005283:Fentanyl