Heroin: Difference between revisions

==Pharmacology==

Heroin itself is an inactive drug, but it is metabolized into [[morphine]] when inserted into the body.<ref name="Sawynok1986">{{cite journal | vauthors=((Sawynok, J.)) | journal=Canadian Journal of Physiology and Pharmacology | title=The therapeutic use of heroin: a review of the pharmacological literature | volume=64 | issue=1 | pages=1–6 | date=1 January 1986 | url=http://www.nrcresearchpress.com/doi/10.1139/y86-001 | issn=0008-4212 | doi=10.1139/y86-001}}</ref> When taken orally, heroin undergoes extensive first-pass metabolism via deacetylation, making it a prodrug for the systemic delivery of morphine.<ref name="Sawynok1986" /> When the drug is injected, however, it avoids this first-pass effect, very rapidly crossing the blood–brain barrier because of the presence of the acetyl groups which render it much more fat-soluble, and thus more potent, than [[morphine]] itself.<ref>{{cite journal | vauthors=((Klous, M. G.)), ((Brink, W. V. den)), ((Ree, J. M. V.)), ((Beijnen, J. H.)) | journal=Drug and Alcohol Dependence | title=Development of pharmaceutical heroin preparations for medical co-prescription to opioid dependent patients | volume=80 | issue=3 | pages=283–295 | date=12 December 2005 | url=https://www.sciencedirect.com/science/article/pii/S0376871605001511 | issn=0376-8716 | doi=10.1016/j.drugalcdep.2005.04.008}}</ref>  

Once in the brain, it is deacetylated variously into the inactive 3-monoacetylmorphine and the active 6-monoacetylmorphine (6-MAM). 6-MAM is found in some commercially prepared batches of black tar heroin, often found on the west coast of the United States. It is then deacetylated into morphine, which binds to [[μ-opioid receptors]]. Heroin itself exhibits relatively low affinity for the μ receptor, suggesting that much of the psychoactive effects of the substance come from the metabolites of heroin rather than the diacetylmorphine itself.<ref>{{cite journal | vauthors=((Inturrisi, C. E.)), ((Schultz, M.)), ((Shin, S.)), ((Umans, J. G.)), ((Angel, L.)), ((Simon, E. J.)) | journal=Life Sciences | title=Evidence from opiate binding studies that heroin acts through its metabolites | volume=33 Suppl 1 | pages=773–776 | date= 1983 | issn=0024-3205 | doi=10.1016/0024-3205(83)90616-1}}</ref>