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Opioids/Opiates Narcotics: (Opioids) These drugs are referred to as the opioid (or opiate) narcotics because of their association with opium Opioids Compounds with opiate-like actions, including, but not confined to opiates (e.g., synthetic, endogenous opioids) Opiates alkaloids found in the opium poppy (Papaver somniferum) [Gk. opion = “poppy juice”] Types of opioids 1. Naturallyoccurring opium sap from opium poppy Two major active alkaloids morphine codeine What are narcotics? The term narcotic currently refers to naturally occurring substances derived from the opium poppy and their synthetic substitutes. What are narcotics? For the most part, the opioid narcotics possess abuse potential, but they also have important clinical value (analgesic, antitussive). The term narcotic has been used to label many substances, from opium to marijuana to cocaine. Morphine Morpheus (god of Dreams) -son of Hypnos ~ 10% of opium by weight N CH 3 H HO O Morphine OH Pharmacological effects Morphine is a particularly potent pain reliever and often is used as the analgesic standard by which other narcotics are compared. With continual use, tolerance develops to the analgesic effects of morphine and other narcotics. Physicians frequently underprescribe narcotics, because of fear of causing narcotic addiction. Codeine methylmorphine ~ 0.5% of opium Semi-synthetics Semi-synthetics Heroin diacetylmorphine addition of two acetyl groups to morphine ~ 10x more potent than morphine pharmacological effect usually thought to be identical to morphine in brain: heroin > morphine (new data suggest morphine and heroin may have different actions; 1999) Semi-synthetic analgesics Hydromorphone (Dilaudid®) Hydrocodone (Hycodan®) Oxycodone (Percodan®) Synthetics Phenylpiperidines Fentanyl “china white” Meperidine (Demerol®) (MPPP) Methadone & Congeners Methadone (Dolophine®) Propoxyphene (Darvon®) Benzomorphans Pentazocine (Talwin®) N CH 3 C O CH 2 CH 3 O Pethidine (Meperidine) H 3C N H C (CH 3)2 CH 2 O Methadone CH 3 Analgesic potency Analgesic Mild to moderate pain potency codeine, propoxyphene (Darvon®) Moderately severe pain meperdine (Demerol®) Severe pain heroin, hydromorphone (Dilaudid®) Endogenous opioids Enkephalins, endorphins and dynorphins Morphine & codeine? History of use - opium Since recorded history Ingredient in all sorts of medicinal preparations History of use - morphine “Soldiers disease” History of use Ads for heroin Analgesia Heroin vs. Morphine difference pharmacokinetic? recent evidence for different receptors - MOR-1 knockouts Reinforcing effects Reinforcing effects All classical opioid drugs of abuse have a preference for µ sites (e.g., morphine, heroin, methadone, fentanyl etc.) may contribute, but little known compounds are not self-administered psychomimetic and aversive in humans The history of narcotics The history of narcotics A 6,000-year-old Sumerian tablet The Egyptians The Greeks Arab traders China and opium trade The Opium War of 1839 American opium use Abuse, tolerance, dependence, and withdrawal All the opioid narcotic agents that activate opioid receptors have abuse potential and classified as a schedule drugs. An estimated 2.5 million people in the U.S abuse heroin or other narcotics. Tolerance begins with the first dose of a narcotic, but does not become clinically evident until 2 to 3 weeks of frequent use. Abuse of opioid narcotics Tolerance occurs most rapidly with high doses given in short intervals. Doses can be increased as much as 35 times in order to regain the narcotic effect. Physical dependence invariably accompanies severe tolerance. Psychological dependence can also develop with continual narcotic use. Heroin Abuse Heroin is classified as a Schedule I drug. Heroin is the most widely abused illegal drug in European and Far Eastern countries. Heroin was illicitly used more than any other drug of abuse in the U.S. (except for marijuana) until 15 years ago, when it was replaced by what drug? Cocaine Heroin combinations Pure heroin is a white powder Heroin is usually “cut” (diluted) with lactose When heroin 1st enters the U.S., it may be 95% pure, by the time it is sold, it is 3 to 5% pure Heroin has a bitter taste and often cut with quinine Heroin and fentanyl (Tango and Cash or Goodfellas) Heroin jeopardy A. Approximately 3,000 to 4,000 deaths Q. How many deaths occur annually in the United States from heroin overoses? A. 500,000 to 750,000 Q. What is the estimated number of heroin addicts in the United States A. These locations serve as gathering places for addicts Q. What are “shooting galleries”? Stages of dependence When narcotics such as heroin are first used by people not experiencing pain, the drugs can cause unpleasant, dysphoric sensations. Euphoria gradually overcomes the aversive effects. The positive feelings increase with narcotic use, leading to psychological dependence. Stages of dependence After psychological dependence, physical dependence occurs with frequent daily use, which reinforces ant narcotic abuse. If the user stops taking the drug after physical dependence has occurred severe withdrawal symptoms result. Methods of administration Sniffing the powder (insufflating) Injecting it into a muscle (intramuscular) Smoked Mainlining (intravenous injection) Heroin addicts and AIDS 40 to 50% of IV heroin users have been exposed to the AIDS virus Withdrawal symptoms After the effects of the heroin wear off, the addicts has only a few hours in which to find the next dose before severe withdrawal symptoms begin. A single “shot” of heroin lasts 4 to 6 hours Withdrawal symptoms - runny nose, tears, minor stomach cramps, loss of appetite, vomiting, diarrhea, abdominal cramps, chills, fever, aching bones, muscles spasms Other narcotics Morphine Methadone Fentanyl Hydromorphone Meperidine MPTP Codeine Pentazocine Propoxyphene Narcotic-related drugs Dextromethorphan Clonidine Naloxane Major effects Analgesia Relief of pain in absence of impairment in other sensory modalities Euphoria - Pleasure Produce sense of well being, reduce anxiety, positive feelings Other effects Nausea & vomiting Respiratory depression Miosis Gastrointestinal effects Cough Suppression Motor effects Sensitization Psychomotor stimulant effects Rewarding effects (conditioned place preference) Analgesia Spinal actions Dorsal horn of spinal cord primary pain afferents Dorsal horn Ventral horn 4.2 Analgesia Spinal actions inhibit incoming pain signals Projection neuron Opioid receptor Sensory neuron + Spinal cord 12.8