Opioid analgesics 2-prof azza
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Opioid analgesics 2-prof azza Presentation Transcript

  • 1. Opioid Analgesics BY PROF. AZZA EL-MEDANY
  • 2. CLASSIFICATION    Natural ( Morphine) Semisynthetic ( Codine ) Synthetic ( Mepiridine, Methadone, Fentanyl, Tramadol )
  • 3. Another Classification     Strong agonist Moderate agonists Mixed agonists /antagonists Pure antagonist
  • 4. Mechanism of actions   Binding to opioid receptors (mu,delta, kappa ,sigma ) at presynaptic nerve fibres resulting in decreasing calcium influx leading to decrease in releasing excitatory neurotransmitters Post synaptic activation of receptors increase potassium efflux (hyperpolarization )
  • 5. Morphine ( Natural & Strong agonist) PHARMACOKINETICS :  ROUTES OF ADMINISTRATION  METABOLISM  DISTRIBUTION  EXCRETION
  • 6. Routes of administration     Oral absorption is erratic IMI , SC injection are preferred Chronic pain , slow release preparation Non medical route , inhalation of powder or smoke
  • 7. Metabolism & excretion  In liver to active metabolite ( morphine -6 glucuronide & morphine -3 glucuronide  Half-life 4-6 hours. Crosses BBB & placental barrier Excreted in urine  
  • 8. Pharmacological actions  Analgesia Without loss of consciousness Severe type of pain
  • 9. Sedation Euphoria
  • 10. Respiration    Respiratory depressant which is dose dependent Large dose causes respiratory failure & death Reduce the sensitivity of respiratory center to CO2
  • 11. Eye  Miosis ( pin point pupil) Through mu & kappa receptors at Edinger westphal neuclus of 3rd nerve
  • 12. Cough center  Antitussive Potent depressant for cough center
  • 13. Histamine release  From mast cells ( urticaria, sweating , vasodilataion , bronchospasm )
  • 14. Endocrinal effect  Decrease : LH, FSH, ACTH , testosterone  Increase : Prolactin, growth hormone, ADH leading to urine retention
  • 15. Nausea & Vomiting  Stimulation of CRTZ
  • 16. GIT    Constipation Constrict biliary smooth muscle may result in biliary colics Sphincter of Oddi may constrict resulting in reflux of biliary & pancreatic secretions & elevated plasma lipase & amylase
  • 17. Urinary System    Decrease in renal function Urine retention Spasm of smooth muscles of ureter causing renal colics
  • 18. Uterus  Prolong labor
  • 19. CVS  Large dose causing hypotension & bradycardia  With respiratory depression & retention of CO2 causing cerebral vasodilataion & ↑ in CSF pressure
  • 20. CLINICAL USES         CANCER PAIN SEVERE BURN SEVERE VISCERAL PAIN ( except, renal & biliary colics , acute pancreatitis ) DIARRHOEA COUGH ACUTE PULMONARY OEDEMA Myocardial ischemia PREANAESTHETIC MADICATION
  • 21. ADVERSE EFFECTS         RESPIRATORY DEPRESSION NAUESEA & VOMITING CONSTIPATION URINE RETENTION HYPOTENSION ALLERGY TOLERANCE ( not to mitotic, convulsant, or constipating effects ) ADDICTION ( abstinence syndrome)
  • 22. Withdrawal manifestations      Severe body ache Insomnia Diarrhea Goose flesh Lacrimation
  • 23. CONTRAINDICATIONS      HEAD INJURY PREGNANCY BRONCHIAL ASTHMA or impaired pulmonary function Liver & Kidney diseases (including renal& biliary colics ) Endocrine diseases ( myxedema & adrenal insufficiency)
  • 24. Continue    Old people are more sensitive ( decrease in metabolism , lean body mass & renal function ) Not given to infants With MAOI
  • 25. Meperidine ( Pethidine)    Synthetic Strong agonist More effective on kappa receptors
  • 26. PHARMACOKINETICS      Well absorbed orally (Has a high oral bioavailability ) Given also by IMI Half-life ( short ) 2-4 hours Give an active metabolite which has CNS stimulant effect Excreted in urine
  • 27. Pharmacological Actions     Less analgesic , less constipating ( weak effect ) , less depressant on foetal respiration than morphine Atropine –like action Smooth muscle relaxant effect No cough suppressant effect
  • 28. CLINICAL USES      Cancer pain Severe burn Severe visceral pain( renal & biliary colics ) Obstetric analgesia Preanaesthetic medication
  • 29. ADVERSE EFFECTS        Tremors & Convulsions Hyperthermia Hypotension Tolerance & Addiction Burred vision Dry mouth Urine retention
  • 30. METHADONE     SYNTHETIC OPIOID POTENT ANALGESIC AS MORPHINE GIVEN BY ORAL , I.V., S.C., AND RECTAL HAS A HIGHER ORAL BIOAVAILABILITY THAN MORPHINE
  • 31. CONTINUE     LONG PLASMA HALF- LIFE ( 24 hrs ) LESS EUPHORIC THAN MORPHINE PRODUCES MILD WITHDRAWAL SYMPTOMS TOLERANCE & PHYSICAL DEPENDENCE DEVELOP MORE SLOWLY THAN MORPHINE
  • 32. CLINICAL USES  Control withdrawal symptoms of dependant abusers from heroin & morphine  Neuropathic & cancer pain
  • 33. CODEINE       Synthesized commercially from morphine Less analgesic & euphoric than morphine Given orally Potent antitussive Always given in combination with aspirin or acetaminophen Addicting drug
  • 34. DEXTROMETHORPHAN    FREE OF ANALGESIC & ADDICTIVE EFFECTS LESS CONSTIPATING THAN CODEINE POTENT AS ANTITUSSIVE
  • 35. Fentanyl       Synthetic drug More potent as analgesic than morphine Rapid onset & very short duration of action (15-30 min ) Used as I.V. anaesthesia IN cancer pain as transdermal patches Has a respiratory depressant effect
  • 36. Sufentanyl, Alfentanyl & Remifentanil   Sufentanyl more potent than fentanyl Other two are less potent with shorter duration of action
  • 37. Heroin      Strong agonist Crosses BBB Converted to morphine No medical use Strong addicting drug
  • 38. TRAMADOL ( Synthetis )     Centrally acting analgesic through inhibition uptake of norepinephrine & serotonin Binds to mµ receptor. Less potent as analgesic than morphine Undergoes extensive metabolism
  • 39. CONTINUE   Given orally ( high oral bioavailability) & by different other routes Used in : mild & moderate acute & chronic visceral pain during labor
  • 40. ADVERSE EFFECTS & CONTRAINDICATIONS    Seizures , Nausea , Dry mouth, Dizziness , Sedation Less adverse effects on respiratory & C.V.S. Contraindicated in patients with history of epilepsy
  • 41. Loperamide    Can not cross BBB Lacking analgesic effect Used for treatment of chronic diarrhea
  • 42. OPIOIDS WITH MIXED RECEPTORS ACTIONS       BUPRENORPHINE Partial Mu receptor agonist Long duration of action Poor oral bioavailability Given parntrally ,Sublingually , Or as nasal spray Excreted in the bile & urine
  • 43. CONTINUE    Acts as morphine in normal patient & precipitate withdrawal symptoms in morphine users. Causes less : sedation , respiratory depression , hypotension than morphine. Used in detoxification & maintenance of heroin abusers
  • 44. Pentazocine      Agonist at KAPPA & antagonist at MU Receptors Given orally or parentrally Has a short duration of action Less potent , less euphoric than morphine High doses causes respiratory depression
  • 45. Adverse effects        Hallucination , nightmares , convulsions Increase Blood Pressure & Heart rate Precipitate withdrawal symptoms when given to patients dependent on morphine CONTRAINDICATIONS With Morphine Heart diseases & Hypertension Epilepsy
  • 46. OPIOID ANTAGONISTS      NALOXONE PURE ANTAGONIST AT MU RECEPTORS HAS a rapid onset of action (SECONDS ) & Short duration of action (30-60min ) Is available for I.V. route Teatment of OPIOID overdoses ( ACUTE TOXICITY )
  • 47. NOTICE  Naloxone completely reverse respiratory depression produced by opioid over doses , Incompletely reverse their analgesic effects.
  • 48. Naltrexone    Has a Long duration of action (10 HRS ) Given Orally Used clinically in : 1- Treatment of chronic Alcoholism 2-Control withdrawal symptoms of addicts 3- Reduce craving for alcohol in chronic alcoholics
  • 49. OPIOID ANTAGONISTS     In normal individual do not produce any effect. IN dependent individual Precipitate withdrawal symptoms NO Tolerance TO Their Antagonistic action NO withdrawal symptoms When Withdrawn After Chronic Use