Oripavine

Oripavine is an opiate and the major metabolite of thebaine. It is the prototypical molecule of a series of semi-synthetic opioids which includes buprenorphine. Although its analgesic potency is comparable to morphine, it is not used clinically due to its severe toxicity and low therapeutic index.

Pharmacological Properties
Oripavine possesses an analgesic potency comparable to morphine; however, it is not clinically useful due to severe toxicity and low therapeutic index. In both mice and rats, toxic doses caused tonic-clonic_seizures followed by death, similar to thebaine.

Oripavine has a potential for dependence which is significantly greater than that of thebaine but slightly less than that of morphine.

Legal Status
Due to the relative ease of synthetic modification of oripavine to produce other narcotics (by either direct or indirect routes via thebaine), the World Health Organization's Expert Committee on Drug Dependence recommended in 2003 that oripavine be controlled under Schedule I of the 1961 Single Convention on Narcotic Drugs. On March 14 2007, the United Nations Commission on Narcotic Drugs formally decided to accept these recommendations, and placed oripavine in the Schedule I.

Until recently, oripavine was a Schedule II drug in the United States by default as a thebaine derivative, although it was not explicitly listed. However, as a member state under the 1961 Single Convention on Narcotic Drugs, the US was obligated to specifically control the substance under the Controlled Substances Act following its international control by the UN Commission on Narcotic Drugs. On September 24 2007, the Drug Enforcement Administration formally added oripavine to Schedule II.