Dependence potential of oripavine.

The dependence potential of thebaine is at least partially attributed to oripavine which is one of the principal metabolites of thebaine. The analgesic potency of oripavine in mice is found to be much higher than that of thebaine and comparable to morphine. The reinforcing effect of this substance also appears to be more potent than thebaine. In rats the physical dependence potential of oripavine at a dose of 4 mg/kg is almost comparable to that of morphine at 0.5 mg/kg. Studies carried out on monkeys show that oripavine possesses weak morphine-antagonist properties. Further pharmacological studies of the metabolites of thebaine are recommended.