page_title: 6-Monoacetylmorphine
section_title: Pharmacology
hierarchical_section_title: 6-Monoacetylmorphine / Pharmacology
context_page_description: 6-Monoacetylmorphine is one of three active metabolites of heroin, the others being morphine and the much less active 3-monoacetylmorphine.
context_section_description: 6-MAM occurs as a metabolite of heroin. Once it has passed first-pass metabolism, 6-MAM is then metabolized into morphine or excreted in urine.
  Heroin is rapidly metabolized by esterase enzymes in the brain and has an extremely short half-life.  It has also relatively weak affinity to μ-opioid receptors because the 3-hydroxy group, essential for effective binding to the receptor, is masked by the acetyl group.  Therefore, heroin acts as a pro-drug, serving as a lipophilic transporter for the systemic delivery of morphine, which actively binds with μ-opioid receptors.
  6-MAM 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 6-position in order to be bioactivated; this makes 6-MAM somewhat more potent than heroin.
caption: Black tar heroin
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