Tolerance-like phenomenon of nifedipine-induced antinociception.
We confirmed that repeated injection of nifedipine evokes an acute tolerance in rats. Nociceptive response was assessed by the tail-flick test. Rats, randomly divided into 3 groups, were injected once a week for 1 month with nifedipine intraperitoneally at the doses of: (A) 2 mg/kg; (B) 10 mg/kg; and (C) 10 mg/kg at the first injection and followed by dimethyl sulfoxide in the subsequent injections. After one month, group A and C were injected with 10 mg/kg and group B with 30 mg/kg nifedipine. In group A, 2 mg/kg of nifedipine did not change the TF latency but its repeated injections prevented the antinociceptive effect of 10 mg/kg nifedipine. In group B, only the first dose of 10 mg/kg and the last dose of 30 mg/kg produced a significant antinociception. In group C, the first but not the last dose of 10 mg/kg nifedipine, produced a significant antinociception. Our data suggest that a single dose of 10 mg/kg nifedipine or repeated doses of 2 mg/kg produced a tolerance-like phenomenon in nifedipine-induced antinociception.
Department of Anesthesiology, Chang Gung Memorial Hospital, Taipei, Taiwan.
C H
CH
Wong
V K
VK
Zbuzek
W H
WH
Wu
D000700:Analgesics / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D004361:Drug Tolerance; D008297:Male; D009543:Nifedipine / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D000700:Analgesics; D009543:Nifedipine