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MANAGEMENT OF PAIN

MANAGEMENT OF PAIN. What is pain? How can pain be treated? Cycle-oxygenase inhibitors Opioids. “ OPIOID ANALGESICS Narcotics”. “Analgesia” = “without pain sensation” Opioids: - reduce pain sensation - reduce concern about pain.

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MANAGEMENT OF PAIN

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  1. MANAGEMENT OF PAIN What is pain? How can pain be treated? Cycle-oxygenase inhibitors Opioids

  2. “OPIOID ANALGESICSNarcotics” “Analgesia” = “without pain sensation” Opioids: - reduce pain sensation - reduce concern about pain

  3. OPIUM: exudate of seed capsules of Papaver somniferum 10% morphine OPIUM TINCTURE: laudanum, 10% opium, 1% morphine PAREGORIC: camphorated opium tincture, 0.04% morphine

  4. Opium poppies in Columbia

  5. The milky fluid that oozes from the seed pod of the poppy is opium

  6. Various poppy products

  7. HISTORY OF OPIOIDS 4000 B.C. Sumerian pictographs of opium poppy 2000 B.C. Use of opium by Greeks 15th Cent. Laudanum used in Europe A.D. 18th Cent. Opium smoking popular in Orient 1803 Serturner isolated morphine 1800’s Opium wars in China Civil war in U.S.A. 1900’s Heroin Methadone Meperidine Endorphins Naloxone

  8. OPIATES Morphine Heroin Codeine

  9. OPIOID DRUGS Prototype = MORPHINE

  10. MORPHINE BASE

  11. MORPHINE CNS actions Cardiovascular actions Gastrointestinal actions

  12. MORPHINE CNS ACTIONS • Mechanism: Acts at brain and spinal opioid receptors (especially mu receptors) • Effects 1. Analgesia-selective 2. Euphoria 3. Drowsiness (coma in overdose) 4. Pituitary: increase PRL and ADH, can decrease ACTH 5. Pupils: miosis 6. Respiratory depression 7. Depression of cough center 8. Stimulation of CTZ, depression of VC 9. Depression on multineuronal reflexes 10. Generalized stimulation (rare) 11. Central cardiovascular, GI actions

  13. MORPHINE CARDIOVASCULAR ACTIONS A. Orthostatic hypotension 1. Peripheral vasodilation (?histamine release, inhibition of NE release?) 2. Sympathetic inhibition (CNS) B. Cerebral vasodilation (hypercapnia)

  14. MORPHINE GASTROINTESTINAL ACTIONS A. Increased incidence and amplitude of circular muscle contraction B. Decreased gastric emptying C. Decreased transit, constipation D. Spasm of biliary tract, sphincter of Oddi

  15. OPIOID DRUGSSITES OF ACTION

  16. OPIOID DRUGSActions

  17. OPIOID DRUGS

  18. DISPOSITION OF OPIATES ABSORPTION DISTRIBUTION BIOTRANSFORMATION EXCRETION

  19. Fig. 1. Effect of route of administration on plasma-free morphine levels. Means  S.E. are shown.

  20. HAZARDS Respiratory depression GI: nausea, vomiting, constipation Orthostatic hypotension Perceptual disturbance Dependence

  21. HEROIN(Diacetylmorphine) 1. Analgesic 2. Penetrates into brain well, potent 3. Hydrolyzed to monoacetylmorphine and to morphine 4. Other pharmacology like morphine

  22. Heroin is manufactured in remote “laboratories” using rudimentary equipment

  23. Heroin removed from latex balloons prior to being packaged for street sales.

  24. Heroin repackaged for sale on the streets of the United States

  25. CODEINE(Methylmorphine) 1. Analgesic 2. Effective orally 3. Antitussive 4. Low dependence liability 5. Often stimulatory in overdose 6. Some O-demethylated in vivo

  26. MEPERIDINE Shorter duration of action than morphine Not an effective antitussive

  27. MEPERIDINE 1. CNS effects a. analgesia b. euphoria c. respiratory depression d. convulsions (normeperidine) e. pupil response variable 2. Smooth muscle a. spasmogenic but not constipating

  28. METHADONE 1. CNS effects a. analgesia b. respiratory c. antitussive 2. Other actions a. similar to morphine

  29. METHADONE Disposition Well absorbed, orally active Metabolized in liver Long duration of action

  30. DEXTROMETHORPHAN Antitussive Not addicting Not analgesic

  31. OPIOID ANTAGONISTS Prototype: NALOXONE Naloxone: “pure antagonist” no agonist actions Naloxone: short duration of action

  32. OPIOID ANTAGONISTS (Naloxone, naltrexone) $ Competitive antagonists at opioid receptors $ Rapid reversal of opioid agonist effects - analgesia - respiratory depression - miosis $ Do NOT directly antagonize barbiturates, alcohol, benzodiazepines

  33. MIXED AGONIST-ANTAGONIST Nalorphine (Nalline) Pentazocine (Talwin) Nalbuphine (Nubain) Butorphanol (Stadol) Buprenorphine (Temgesic) Cyclazocine

  34. MIXED OPIOID AGONISTS-ANTAGONISTS 1. NALORPHINE: not used as agonist, replaced by naloxone as antagonist (can induce respiratory depression). 2. PENTAZOCINE Used clinically as agonist Analgesic Euphoria or dysphoria Mild respiratory depression Moderate abuse potential 3. BUTORPHANIL About like pentazocine

  35. OPIOID TOLERANCE Cellular tolerance Cross-tolerance with other opioids No cross-tolerance to other drug classes

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