The antinociceptive effects of intraperitoneal administration of central acting drugs in mice

Abstract

The antinociceptive effects of intraperitoneal injection of central acting drugs on tail-flick response of the mice were determined. This study was performed after the approval of Adnan Menderes University Laboratory Animals Ethics Committee. Initially, weight of mice were measured and their tail flick responses were recorded. Twenty-four hours later, diazepam (5 and 50 mg/kg), midazolam (1 and 10 mg/kg), phenytoin (50 mg/kg), biperiden (30 mg/kg), nicotine (5 mg/kg) and atropine (30 mg/kg) were administrated intraperitoneally. The tail-flick latencies were reduced significantly in 5 mg/kg diazepam and 10 mg/kg midazolam injected groups. On the other hand, the tail-flick latencies were increased significantly in diazepam (50 mg/kg), phenytoin, biperiden, and nicotine injected groups. These results suggest that phenytoin, biperiden, and nicotine have antinociceptive and diazepam and midazolam have dose-dependent hyperalgesic effects. In conclusion, hyperalgesic and antinociceptive effects of central acting drugs should be considered when they are combined with analgesic drugs during acute or chronic pain treatment.