Heroin is rapidly converted to 6-monoacetylmorphine (6-MAM or 6-AM) and then to morphine. Heroin has an extremely short half-life of about two to six minutes. The half-life of 6-monoacetylmorphine is six to 25 minutes and is excreted for approximately six to eight hours following heroin use. Because heroin has such a short half-life, it is rarely detected in drug tests. Its metabolites, 6-MAM and morphine are usually quantitated in confirmatory testing of heroin. The presence of 6-MAM in the presence of morphine is definitive proof of heroin use. However, the detection of morphine in the absence of 6-MAM does not rule out heroin use because 6-AM is excreted for only a few hours after use.
