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

2. “ OPIOID ANALGESICS Narcotics” “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 1803Serturner isolated morphine 1800’sOpium wars in China Civil war in U.S.A. 1900’sHeroin Methadone Meperidine EndorphinsNaloxone

8. OPIATES Morphine Heroin Codeine

9. OPIOID DRUGS Prototype = MORPHINE

11. MORPHINE BASE

12. MORPHINE CNS actions Cardiovascular actions Gastrointestinal actions

13. MORPHINE CNS ACTIONS A.Mechanism: Acts at brain and spinal opioid receptors (especially mu receptors) B.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

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

16. 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

17. OPIOID DRUGS SITES OF ACTION

18. OPIOID DRUGS Actions

19. OPIOID DRUGS

20. DISPOSITION OF OPIATES ABSORPTION DISTRIBUTION BIOTRANSFORMATION EXCRETION

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

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

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

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

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

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

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

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

34. 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

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

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

39. DEXTROMETHORPHAN Antitussive Not addicting Not analgesic

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

44. 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

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

46. 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

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

51. OPIOID DEPENDENCE Users seek euphoria, freedom from anxiety, pleasure Dependence primary psychological physical secondary psychological

52. OPIOID DEPENDENCE Withdrawal syndrome abstinent precipitated with antagonist

53. HEROIN/MORPHINE WITHDRAWAL Early abstinence 8 hrlacrimation, rhinorrhea, yawning, sweating 12 hr“yen” (restless sleep), miserable, dilated pupils, anorexia, gooseflesh, restlessness, irritability, tremor 48 hrsymptoms peak, severe sneezing, yawning, diarrhea, nausea, vomiting, waves of gooseflesh, alternate chills and sweating, weakness, depression, cramps, bone pain, muscle spasm, tachycardia, hypertension, sexual orgasm, dehydration 7 daysacute phase ended Protracted abstinence Weeks, months

54. OVERDOSE Triad Coma Respiratory depression Pinpoint pupils Management Support of vital functions Antidotal therapy Narcotic antagonist