Antinociceptive Effect of Promethazine in Mice

Objective(s) The present study was undertaken to investigate the nociception activity of promethazine, a tranquillizer devoid of hypnotic activity in mice. Materials and Methods Antinociception was evaluated, using the acetic acid-induced writhing, tail flick, hot plate and formalin pain tests. Results Promethazine (۴ and ۶ mg/kg) and acetylsalicylic acid (۱۰۰ mg/kg) produced a significant inhibition of the second phase response in the formalin pain model (P<۰.۰۵) and the drug couldn’t show an antinociceptive effect in the first phase. Morphine (۱۰ mg/kg) inhibited both first and second phase response (P<۰.۰۱). Drug also showed a dose-dependent inhibition of acetic acid-induced abdominal writhes. The tail flick and hot plate latency weren’t different from control (P>۰.۰۵) and administration of naloxone (۰.۱ mg/kg) couldn't block the antinociceptive effect of promethazine. Conclusion The data obtained suggest that antinociceptive effects of the promethazine may be mediated via peripheral and not central mechanisms.

Keywords:

Antinociceptive , Formalin test , Hot plate , Promethazine , Tail flick , Writhing test