Opiate Metabolism
- Heroin is rapidly hydrolyzed by conversion of an acetoxy group (-OCOCH3) to a hydroxyl group (-OH) by esterase enzymes in the brain to 6-monoacetylmorphine (6-MAM or 6-AM). Trace amounts of 6-AM are excreted for approximately six to eight hours following heroin use.
- 6-AM is hydrolyzed to morphine by replacement of the remaining acetoxy group (-OCOCH3) with a hydroxyl group (-OH) by esterase enzymes. The rest of the metabolic pathway follows that of morphine.
Heroin has an extremely short half-life of about two to six minutes. The half-life of 6-acetylmorphine is six to 25 minutes.
Interpretation
- Because heroin has such a short life, its metabolites, 6-AM and morphine, are quantitated in confirmatory testing of heroin. Heroin itself is rarely detected in drug tests.
- The presence of 6-AM in the presence of morphine is definitive proof of heroin use. However, the detection of morphine in the absence of 6-AM does not rule out heroin use because 6-AM is excreted for only a few hours after use.
