antinociceptive interaction between adenosine and carbamazepine in mice

there are several reports that adenosine and carbamazepine have pharmacodynamic interaction. i n this study the antinociceptive interaction o f these two agents was evaluated in mice by the hot plate test. agents were injected intraperitoneally. 0.2 and 0.4 mg/kg doses of r-phenylisopropyladenosine (r-pia) substantially showed antinociceptive effects. carbamazepine had antinociceptive actions except at a dose of 0.8 mg/kg. theophylline (12.5 mg/kg), as a non-selective antagonist of adenosine receptors, showed a nociceptive effect. dipyridamole, an uptake blocker of adenosine, had no antinociceptive effect even with a dosage of 90 mg!k:g. theophylline did not decrease the antinociceptive effect of carbamazepine, while dipyridamole increased the antinociceptive effect of carbamazepine 30 min utes after administration. carbamazepine (8 mg/kg) inhibited the antinociceptive effect of rpia. this study supports the possibility that the interaction between adenosine and carbamazepine may be related to their actions at adenosine receptor sites in the brain.