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IVMS-CNS Pharmacology- Intro to Drugs of Abuse II-Opioids

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  • 1. CNS Pharmacology- Introduction to Drugs of Abuse II/Opoids Prepared and Presented by: Marc Imhotep Cray, M.D. Professor Basic Medical Sciences Clinical: E-Medicine Articles Opioid Abuse
  • 2. 2
  • 3. 3 OPIOIDS or NARCOTICS I. Morphine II. Codeine III. Meperidine IV. Methadone V. Designer Opioids
  • 4. 4 I. Morphine, Heroin, Hydromorphone,Oxymorp hone A. Pharmacology - Heroin is very lipid soluble - Short half-life (t½ = 3 min) - Heroin  6-mono-acetyl morphine  morphine OPIOIDS or NARCOTICS
  • 5. 5 Desirable Effects:  Euphoria  Sedation  Relief of anxiety and various other forms of distress  Analgesia  Depression of cough reflex* Subjective CNS effects:  Drowsiness  Difficulty concentrating  Apathy  Decreased physical activity  Lethargy  Extremities feel heavy and the body feels warm OPIOIDS or NARCOTICS
  • 6. 6 Undesirable Effects: Dysphoria Dizziness Nausea Vomiting Constipation* Biliary tract spasm Urinary retention OPIOIDS or NARCOTICS
  • 7. 7 OPIOIDS 1).Psychological dependence  I.V. use preferred by most users => “rush” or “high”  Oral abuse => meperidine  Emotional or motivational symptoms, “craving”.  Iatrogenic addiction 2).Physical dependence  May develop on repeated use of therapeutic doses  Narcotic Abstinence Syndrome (Withdrawal)
  • 8. 8  Withdrawal, onset related to time-effect curve and t½ of narcotic  6-8hr =>drug seeking behavior, restless, anxious  8-12hr => Pupils dilated, reactive to light; increased pulse rate, blood pressure, yawning; chills; rhinorrhea; lacrimation; gooseflesh; sweating; restless sleep.  48-72 hrs (peak) => All of the above plus muscular weakness, aches (cramps) and twitches; nausea, vomiting and diarrhea;  temperature and respiration rate elevated; heart rate and blood pressure elevated; dehydration OPIOIDS
  • 9. 9  Withdrawal, onset related to time-effect curve and t½ of narcotic Not life threatening, no convulsions, no delirium, no disorientation Treatment of withdrawal: symptoms => clonidine OPIOIDS
  • 10. 10 B. Concurrent or Substitute use:  Alcohol, sedatives or cocaine/amphetamines C. Tolerance  Yes, develops to all effects except constipation and pupillary effects  Cross-tolerance and cross- dependence with other narcotics (Implication in narcotic addict => need to increase dose to experience euphoria)  High level of tolerance is possible; huge amounts of drug can be tolerated after chronic use; potential for overdose if relapse occurs and addict resumes with same high level of drug  Implications for chronic administration for pain OPIOIDS
  • 11. 11 D. Toxicology 1.Tissue and organ toxicity - “Heroin lung” with acute overdose - No apparent tissue damage 2. Psychic toxicity - Acute and chronic drive reduction 3. Behavioral toxicity - Criminal behavior to obtain drugs 4. Associated diseases/Death - Unsterile syringes: AIDS, hepatitis, SBE, malaria, tetanus, localized infections, pulmonary infiltration of contaminants Neuropathies, Violent deaths OPIOIDS
  • 12. 12 E. Acute Intoxication/Overdose 1. Disruption of central control of peripheral sympathetic activity - Respiratory depression => apnea=> DEATH - Circulatory depression => BP - Pupils constricted (may be dilated with meperidine) - Convulsions with propoxyphene and meperidine - - Arrhythmias w propoxyphene - Pulmonary edema -  Reflexes OPIOIDS
  • 13. 13 E. Acute Intoxication/Overdose (con’t) 2. CNS depression - Euphoria/dysphoria =>drowsiness =>sedation => coma Treatment of overdose => Naloxone (Narcan ®) I.V. (0.1-0.4 mg) repeated as necessary Short acting opioid antagonist (1-2 hrs). Give every 30 minutes until patient is controlled Follow by methadone Nalmefene could also be used, has longer half-life Also used to control and reverse effects of therapeutically administered narcotics (anesthesia and labor) OPIOIDS
  • 14. 14 F. Treatment of Depenndence  Narcotic dependence is one of very few cases where there are partially effective pharmacological therapies 1. Opioid replacement a. Methadone, Dolophin®  Long half-life produces a longer but less stressful withdrawal (although more prolonged).  Onset =>24hrs, peak =>5-7 days  Lessens the “highs” and “lows” of withdrawal  Oral administration OPIOIDS
  • 15. 15 b. LAAM (L-a-acetyl methadol, methadyl acetate)  Structurally similar to methadone.  Longer-acting opiate  Taken orally in liquid form, lasts 72hrs (visits 3 X a week)  “Take home" medication OPIOIDS
  • 16. 16 OPIOIDS c. Buprenorphine  Partial agonists which substitutes for low doses of opioids but antagonizes high doses  Can be administered sublingually every 24-48 hours as an alternative to methadone
  • 17. 17 F. Treatment of Dependence  Major problem in detoxification and maintenance of abstinence is the motivational component of the CNS effect, which is responsible for the “drug craving” sensations,  Also conditional dependence and social factors play an important role. OPIOIDS
  • 18. 18 Opiate Antagonists cause precipitated abstinence Naltrexone:  Used for the long term maintenance of abstinence  Long half-life, oral, 3 times a week Naloxone:  Use in life- threatening situations for overdose  Short half life (1-2-hrs) control and reverse effects of therapeutically administered narcotics (anesthesia and labor). OPIOIDS
  • 19. 19 II.Codeine (Methylmorphine); Dihydrocodeine; Hydrocodone (Dicodid®, Hycodan®); Oxycodone (Percodan®). A. Pharmacology  << Potent than morphine IM, but almost never administered parentally  "Weak" opioids.  Used as a cough suppressants (antitussive) and combined with aspirin and acetaminophen as painkillers.  Dependence liability < < than morphine OPIOIDS
  • 20. 20 III. Meperidine (Demorol®); Alphaprodine, (Nisentil®) A. Pharmacology - Less potent than morphine - IM More rapid onset, shorter duration Similar to heroin - Used in anesthesiology - Dependence liability - Same as Morphine OPIOIDS
  • 21. 21 IV. Methadone A. Pharmacology  Pharmacodynamic profile very similar to morphine  Longer acting (10 hrs) vs Morphine (4-5 hrs)  Equipotent and equieffective to morphine  Tolerance and dependence develop more slowly than with morphine  Withdrawal signs and symptoms are milder but more prolonged  Use for detoxification or maintenance of a heroin addict OPIOIDS
  • 22. 22 IV. Methadone B. Concurrent or substitute use - Yes Other narcotics C. Tolerance: Same as Morphine, Cross- tolerance with other narcotics D. Acute intoxication/Overdose: Similar to other narcotics E. Withdrawal: Same as Morphine F. Treatment: None G. Mechanism of action: m opioid receptors OPIOIDS
  • 23. 23 V. Designer Opioids a. MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine). A meperidine/heroin-like drug, MPTP was synthesized in the 1980’s. It contained MPP+ impurities that cause Parkinson's like-symptoms in the young adults who used it by destroying DA neurons. b. Fentanyl (Sublimaze) China White: alpha-methyl fentanyl => deaths by overdose 6000 times more potent than morphine OPIOIDS
  • 24. 24 G. Mechanism of action 1. Anatomy of m opioid receptors: nucleus accumbens (N. Acc.), ventral tegmental area (VTA), caudate, thalamus, cortex, spinal cord2. Actions in thalamus => Sensory modalities. 3. Actions in spinal cord => Analgesia 4. Actions at Mesolimbic dopaminergic system => Reward. Inhibit the release of GABA at the VTA Desinhibition of DA =>DA activity OPIOIDS
  • 25. 25 Mechanism of action Opioids act at the Mesolimbic Dopaminergic System => Reward Center of the Brain. Inhibit the release of GABA at the VTA  Desinhibition of Dopamine neurons  DA activity OPIOIDS
  • 26. 26
  • 27. 27 Drugs and Neurotransmitters & Mental Disorders Interactive Tutorials and Animation Learning Tools  Psychotropic Medications and Neurotransmitters Wisconsin Online  Alcohol and the brain from PBS  The Effect of Drugs and Disease on Snaptic Transmission Harvard Education  Nicotine Patch by Nucleus Communications  GABA Inhibition of Glutamate Bay Area Pain Medical Associates  Acute Pain Bay Area Pain Medical Associates  How Drugs Affect Neurotransmitters INMHA
  • 28. 28 Drugs and Neurotransmitters & Mental Disorders Interactive Tutorials and Animation Learning Tools  Schizophrehia UNIVERSITY OF CENTRAL LANCASHIRE  Epilepsy UNIVERSITY OF CENTRAL LANCASHIRE  Pharmacologic Action of Meth RnCeus.com  How is Pain Produced University of Edinburgh  How Much Alcohol can YOU TAke BBC  The Brain: Understanding Neurobiology Through the Study of Addiction National Institutes of Health  The Science of Addiction University of Utah, Genetic Science Learning Center  Stimulants and Antidepressants Dr. Ian Winship of the University of Alberta  Tranquilizers and CNS Depressants Dr.Ian Winship of the University of Alberta  Genetics of Addiction Genetics Science Learning Center
  • 29. 29 eMedicine Articles on Addiction  Alcohol-Related Psychosis  Alcoholism  Amphetamine-Related Psychiatric Disorders  Caffeine-Related Psychiatric Disorders  Cannabis Compound Abuse  Cocaine-Related Psychiatric Disorders  Hallucinogens  Inhalant-Related Psychiatric Disorders  Injecting Drug Use  Nicotine Addiction  Opioid Abuse  Phencyclidine (PCP)-Related Psychiatric Disorders  Sedative, Hypnotic, Anxiolytic Use Disorders  Stimulants  Substance-Induced Mood Disorders: Depression and Mania

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