Opioids-2009

Opioids-2009 - MEDC 417/502 Dr. McCurdy OPIOID RECEPTOR...

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MEDC 417/502 Dr. McCurdy OPIOID RECEPTOR AGENTS Medicinal Chemistry of Opioids Opioid Analgesics Analgesics (analgetics) are agents that decrease pain (at low doses) Anesthetics produce anesthesia, analgesics produce analgesia Many classes of agents can relieve pain: o NSAIDs (COX enzymes) o General and Local Anesthetics (Voltage gated Na) o Dissociative anesthetics (NMDA receptors) o All CNS depressants (ethanol, barbiturates, anticonvulsants, antipschotics) o Newer targets - Cannabinoid, α 2 , glutamate, nicotine, neurokinin, cytokines, and potassium channels Opioid analgesics is a general term Opioids include: o Opiates - natural or synthetic compounds derived from the opium alkaloids o Synthetic derivatives o Endorphins - endogenous opioid peptides Endorphins, Enkephalins, Dynorphins, Endomorphins, Nociceptin All opioids analgesics are considered addictive substances Morphine Introduction Opium juice is a milky exudate obtained from the opium poppy, Papaver somniferum , and contains many alkaloids Alkaloids containing two main ring systems occur: o Isoquinoline alkaloids (papaverine) o Phenanthrene alkaloids (morphine)
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MEDC 417/502 Dr. McCurdy Main Opium Exudate Components Over 20 isolated Morphine Codeine Noscapine Papaverine Thebaine Writings as early as 3000 bc describe use and abuse of opium Morphine was first isolated from opium by a _______________, Serturner (1803) OPIOID RECEPTORS (GPCRs) Found throughout the brain, spinal cord and peripheral nerves, as well as immune cells Three classical opioid receptors known: o Mu ( μ , MOR, OP 3 ) o Delta ( δ , DOR, OP 1 ) o Kappa ( κ , KOR, OP 2 ) A fourth was identified during cloning o ORL-1 (NOR, OFQ/N, OP 4 ) MU OPIOID RECEPTOR The “morphine” receptor Site for Endomorphins Functions in: o Analgesia o Euphoria o Increases GI transit time o Immune suppression o Emesis o Respiratory depression (volume) o Tolerance o Physical Dependence (withdrawal)
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MEDC 417/502 Dr. McCurdy DELTA OPIOID RECEPTOR Hot target for analgesics Site for Enkephalins Functions in: o Analgesia o Immune stimulation o Respiratory depression (rate) o Tolerance KAPPA OPIOID RECEPTOR Site for Dynorphins Functions in: o Analgesia o Diuresis o Dysphoria o Sedation o Miosis Endogenous Opioid Peptides Endorphins (“endogenous morphine”) β -endorphin - fragment of β -lipotropin from proopiomelanocortin (POMC) Tyr-Gly-Gly-Phe -Met-Thr-Ser-Glu-Lys-Ser-Gln-Thr-Pro-Leu-Val-Thr-Leu-Phe-
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Opioids-2009 - MEDC 417/502 Dr. McCurdy OPIOID RECEPTOR...

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