药理学科E501

1、9NarcoticsOpioids,藥理學科E501 詹銘煥,How do opioids work in your body? Why do human beings like to abuse opioids? Does your body release opioid-like substances?,You have to think,Learning Objectives,Describe the principal pharmacological effects of narcotics and their main therapeutic uses. Identify the m

2、ajor side effects of narcotics. Describe the association of AIDS with heroin abuse. Describe narcotic dependence, tolerance, addiction, to relieve diarrhea Emesis: morphine stimulates the chemoreceptor trigger zone in postrema,Pharmacological effects,Side effects,Severe respiratory depression Consti

3、pation Drowsiness, mental clouding Nausea, vomiting, itching Blood pressure drop Abuse, tolerance, dependence, combined with alcohol or barbiturates; infected with AIDS or hepatitis Heroin and crime: antisocial behavior Patterns of heroin abuse: adolescents and young adults Methods of administration

4、: sniffing, injecting, smoking, snorting Heroin addicts and AIDS Heroin and pregnancy Withdrawal symptoms:,Short-term effects: Rush“, depressed respiration, clouded mental functioning, nausea and vomiting, suppression of pain, spontaneous abortion Long-term effects: Addiction, infectious diseases, f

5、or example, HIV/AIDS anxiety Yawning打呼, perspiration出汗, running nose, tears Pupil dilation, muscle twitches, aching bones & muscles, loss of appetite Insomnia, raised BP, fever, nausea Curled-up position, vomiting, diarrhea, foot kicking,Symptoms of withdrawal from heroin, morphine, & methadone,Stop

6、s using heroin No longer associates with dealers or users of heroin Avoids dangerous activities associated with heroin use Improves employment status Refrains from criminal activity Is able to enjoy normal family and social relationship,Treatment of heroin dependence,Morphine: Methadone: Fentanyls:

7、200X potency of morphine Hydromorphone: an analgesic and cough suppressant Oxycodone: a moderate narcotic analgesic Meperidine: 1/10 potency of morphine Buprenorphine: to treat narcotic abuse & dependence Codeine: treatment of moderate pain & cough Pentazocine: slighter potent than codeine Propoxyph

8、ene: potency of codeine MPTP: a designer tragedy, Parkinson-like disease,Other Narcotics,It relieves moderate to intense pain since it was first isolated in 1803. Analgesic potency: Heroin : morphine : codeine=24 : 12 : 1 Side effects: constricted pupils, respiratory arrest, drowsiness, constipation

9、, nausea, blurred vision, etc The first exposure of morphine is unpleasant, with nausea & vomiting, followed euphoric response in continual use. Tolerance The effects of heroin and morphine are almost identical.,Morphine,It was first synthesized in Germany in 1943, World War II. Its physiological ef

10、fects are the same as those of heroin and morphine Treatment of narcotic withdrawal and dependence Psychological dependence, tolerance, and then physical dependence and addition if repeated use Methadone reduces the cravings associated with heroin use and blocks the high from heroin, but it does not

11、 provide the euphoric rush. Its longer action and a less intense withdrawal response.,Methadone,Narcotic-related drugs,Dextromethorphan: treatment of cough It is mixed with drugs such as alcohol, cocaine, & amphetamine, to give unusual psychoactive interactions. Clonidine: anti-hypertension It relie

12、ves some of the physical effects of opiate withdrawal (vomiting & diarrhea). Naloxone/naltrexone: narcotic antagonists Naloxone is a useful antidote in the treatment of narcotic overdoses.,Dextromethorphan produces a feeling of disassociation or intoxication, but its abuse can lead to psychotic beha

13、vior. In the long term, overdose of DM can cause depression, memory problems, & suicidal tendencies.,Naloxone has an extremely high affinity for -opioid receptors in the central nervous system. Naloxone is a -opioid receptor competitive antagonist, and its rapid blockade of those receptors often produces rapid onset of withdrawal symptoms. Naloxone also has an antagonist action