Monoacetylmorphine

Monoacetylmorphine

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Systematic (IUPAC) name
3-hydroxy-6-acetyl-(5α,6α)-7,8-Didehydro-4,5-epoxy-17-methylmorphinan
Clinical data
Routes of administration	Intravenous
Legal status
Legal status	AU: S9 (Prohibited) UK: Class A US: Schedule I
Identifiers
CAS Number	2784-73-8
ATC code	none
PubChem	CID 5462507
Synonyms	6-acetylmorphine
Chemical data
Formula	C19H21NO4
Molar mass	327.374 g/mol[[]]

6-Monoacetylmorphine (6-MAM) or 6-Acetylmorphine is one of three active metabolites of heroin (diacetylmorphine), the others being morphine and the much less active 3-Monoacetylmorphine (3-MAM).

6-MAM is rapidly created from heroin in the body, and then is either metabolized into morphine or excreted in the urine. Since 6-MAM is a unique metabolite to heroin, its presence in the urine confirms that heroin was the opioid used. This is significant because on a urine immunoassay drug screen, the test typically tests for morphine, which is a metabolite of a number of legal and illegal opiates/opioids such as codeine, morphine sulfate, and heroin. 6-MAM remains in the urine for no more than 24 hours so a urine specimen must be collected soon after the last heroin use, but the presence of 6-MAM guarantees that heroin was in fact used as recently as within the last day. 6-MAM is naturally found in the brain, but in such small quantities that detection of this compound in urine virtually guarantees that heroin has recently been consumed.

Heroin is rapidly metabolized by esterase enzymes in the brain and has an extremely short half life. It has also very weak affinity to μ-opioid receptors because the 3-hydroxy group which is essential for binding to the receptor is masked by the acetyl group. So heroin is just a pro-drug, it is morphine and other minor metabolites that actively bind with μ-opioid receptors.

6-monoacetylmorphine already has a free 3-hydroxy group and shares the high lipophilicity of heroin, so it penetrates the brain just as quickly and does not need to be deacetylated at the 3-position in order to be bioactivated; this makes 6-monoacetylmorphine somewhat more potent than heroin, but it is rarely encountered as an illicit drug due to the difficulty in selectively acetylating morphine at the 6-position without also acetylating the 3-position. This can however be accomplished by using acetic acid with an appropriate catalyst to carry out the acetylation, rather than acetic anhydride, as acetic acid is not a strong enough acetylating agent to acetylate the phenolic 3-hydroxy group but is able to acetylate the 6-hydroxy group, thus selectively producing 6-MAM rather than heroin. The process used in creating black tar heroin actually leaves 6-MAM in the final product, which is one reason why black tar can be less refined, but at the same time more potent than powder varieties of heroin.

See also

• M3G, Morphine-3-glucuronide an inactive metabolite of morphine much as 3MAM is the inactive metabolite of heroin (notably here as morphine is the active metabolite of heroin itself with this chemical of this article subject being the intermediate stage)
• M6G, Morphine-6-glucuronide the active variant in close relation to 6-MAM, being relative as twin metabolites of this articles very metabolite itself, morphine, twinned to a metabolite (3MAM) of a parent compound (heroin) of this article's chemical

References

fr:Monoacétylmorphine