Background: A long-acting analgesic may be particularly desirable in patients suffering from long-lasting pain. The aim of the study was to evaluate the antinociceptive effect of a novel depot of buprenorphine decanoate and its metabolic profiles in human and animal blood.
Methods: Following their intramuscular injections in guinea pigs, the antinociceptive effects of the novel depot of buprenorphine decanoate (in oil) and the traditional dosage form of buprenorphine HCl (in saline) were evaluated. An in vitro metabolic study of buprenorphine decanoate in human and animal blood was also carried out. The antinociception of drugs was evaluated using the plantar test. The blood concentrations of drugs were assayed using a high performance liquid chromatography.
Results: We found that both the buprenorphine HCl (in saline) and buprenorphine decanoate (in oil) produced dose-related antinociceptive effect but of different duration of action. Under an equi-mole basis of 0.6 micromol/kg, the durations of action of buprenorphine HCl and decanoate were 4 and 72 h, respectively. In in vitro metabolic study in human and animal bloods, buprenorphine decanoate was totally converted to buprenorphine. Buprenorphine decanoate is a prodrug of buprenorphine.
Conclusions: Intramuscular injection of the depot of buprenorphine decanoate in guinea pigs produced a dose-related long-lasting antinociceptive effect which was much longer than that of the traditional dosage form of buprenorphine HCl. Moreover, buprenorphine decanoate is a prodrug of buprenorphine.