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Opioids

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Archana Dhavalshankh Halgaonkar

Opioid analgesics are drugs that selectively relieve pain by acting in the central nervous system or on peripheral pain mechanisms without significantly altering consciousness. There are several classifications of opioids including agonists, partial agonists, mixed agonists/antagonists. Morphine is an agonist that provides strong analgesia through inhibition of excitatory neurotransmitters in the spinal cord and altering pain processing in the brain. Adverse effects include respiratory depression, vomiting, sedation, and dependence/tolerance with repeated use. Opioids are commonly used to treat severe pain from fractures, myocardial infarction, cancer, burns and post-operatively.

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OPIOIDANALGESICS DR. ARCHANA DHAVALSHANKH PRO & HEAD, DEPT OF PHARMACOLOGY D Y PATIL MEDICAL COLLEGE, KOLHAPUR
OPIOID ANALGESICS Analgesics are the drugs which selectively relieves pain by acting in the CNS or on peripheral pain mechanisms, without significantly altering the consciousness. Opioids and NSAIDS(Non-opioids) Opioids: any drug which binds to the opioid receptors (pharmacologically related) in the CNS and antagonized by naloxone
OPIOID ANALGESICS- Terminology Opiates: Drugs derived from opium Natural or semi-synthetic Narcotics: Drugs derived from opium or opium like compounds, with potent analgesic effects associated with significant alteration of mood and behavior, and with the potential for dependence and tolerance following repeated administration.
OPIOID ANALGESICS- Classification Agonist Partial Agonist Mixed Agonist & antagonist Morphine Codeine Diacetylmorphine (Heroin) Pholcodine Pethidine Methadone Propoxyphene Levorphanol Tramadol Buprenorphine Meptazinol Nalbuphine Pentazocine Butorphanol
Effects of different Opioid Receptor Stimulation
OPIOID ANALGESICS-Mechanism of action
Pharmacological actions - (CNS ) Analgesia: Strong analgesic Visceral pain is relieved better than somatic pain Degree of analgesia increases with dose Nociceptive pain is better relieved than Neurotic pain Associated reactions to pain are also relieved apprehension, fear and autonomic effects Tolerance to pain is better
MORPHINE Analgesia action Two components spinal and supraspinal Inhibits release of excitatory transmitters from primary afferents at Substantia gelatinosa of dorsal horn Exerted through Interneurons gating of pain At supraspinal level in cortex, midbrain and medulla - alter processing and interpretation and send inhibitory impulses through descending pathway
Pharmacological actions - (CNS ) Sedation: Drowsiness and indifference to surroundings Inability to concentrate and extravagant imagination colorful day dream Apparent excitement Larger doses produce sleep EEG resembles normal sleep Mood effects: In Normal persons calming effect, - mental clouding, - feeling of detachment, - lack of initiative etc. - unpleasant in absence of pain DYSHORIA But in persons with pain & addicts sense of wellbeing, pleasurable floating feelings kick EUPHORIA
Pharmacological actions Neuro-endocrine: GnRH and CRH are inhibited FSH, LH and ACTH levels are lowered only short term tolerance develops Decrease in levels of Sex hormone and corticosteroids, but no infertility Increases ADH release oliguria CVS:NO DIRECT EFFECT ON HEART Vasodilatation histamine release, depression of vasomotor centre and directly on blood vessels decreasing the tone Cardiac work reduction due to consistent vasodilatation GIT: CONSTIPATION Due to direct action on intestine reducing propulsive movement, spasm of sphincters, decrease in all GIT secretions Smooth Muscles: Billiarycolic closure of sph. Of Oddi Bladder: Urinary urgency but difficulty Bronchi- Bronchospasm
Pharmacological actions of Morphine Depression Stimulation Respiratory Centre- Both rate and depth of respiration are diminished. Dangerous in Head injury and asthmatics CTZ sensitize CTZ to vestibular and other impulses Temperature Regulating Centre Vagal Centre - Bradycardia Cough Centre Edinger Westphal Nucleus miosis Vasomotor Centre - high doses cause fall in BP Hippocampal cells convulsions (inhibition of GABA release
Pharmacokinetics AbsorptionandDistribution Variable orally (usually not given orally 1st pass metabolism, given IM or IV) Widely distributed liver, spleen, kidney etc. Enters Brain slowly Readily crosses placental barrier dependence in fetus Metabolism In Liver by glucuronidation water soluble metabolites Morphine-6-glucuronide analgesic in renal failure prolong analgesia Morphine-3-glucoronide No analgesia neuroexcitatory Excretion Via Urine, Plasma t1/2 = 2-3 Hrs Action lasts for 4-6 Hrs Completely eliminated in 24 Hrs Preparation: 10, 15, and 20 mg. (IV: 2 10 mg)
Adverse Effects 1. Respiratory Depression: Infant and Old 2. Vomiting 3. Sedation, Mental Clouding sometimes dysphoria 4. Hypotensive effect 5. Rise in Intracranial Pressure 6. Apnoea: Newborn 7. Urinary retention 8. Idiosyncrasy and allergy 9. Tolerance and dependence 10. Acute Morphine Poisoning: occurs if >50 mg (Lethal dose 250 mg) Gastric lavage with KMNO4, Specific antidote: Naloxone: 0.4 to 0.8 mg IV repeatedly in 2-3 minutes till respiration picks up
Therapeutic uses Analgesic: 1. Long Bone Fracture 2. Myocardial Infarction 3. Terminal stages of cancer 4. Burn patients 5. Postoperative patients 6. Visceral pains pulmonary embolism, pleurisy, acute pericarditis 7. Biliary colic and renal colic 8. Obstetric analgesia 9. Segmental analgesia Other Therapeutic uses Preanesthetic Medication Balanced anesthesia and surgical analgesia Acute Left ventricular failure Cardiac asthma Cough not used but Codeine is used Diarrhoea colostomy - Loperamide, Diphenoxylate
Contraindications 1. Two Extremes of Age 2. Bronchial asthma 3. Respiratory insufficiency empysema 4. Head Injury 5. Shock Hypotension 6. Undiagnosed acute abdomen 7. BHP 8. Renal Failure, Liver diseases and hypothyrodism 9. Unstable personalities
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Opioids

  • 1. OPIOIDANALGESICS DR. ARCHANA DHAVALSHANKH PRO & HEAD, DEPT OF PHARMACOLOGY D Y PATIL MEDICAL COLLEGE, KOLHAPUR
  • 2. OPIOID ANALGESICS Analgesics are the drugs which selectively relieves pain by acting in the CNS or on peripheral pain mechanisms, without significantly altering the consciousness. Opioids and NSAIDS(Non-opioids) Opioids: any drug which binds to the opioid receptors (pharmacologically related) in the CNS and antagonized by naloxone
  • 3. OPIOID ANALGESICS- Terminology Opiates: Drugs derived from opium Natural or semi-synthetic Narcotics: Drugs derived from opium or opium like compounds, with potent analgesic effects associated with significant alteration of mood and behavior, and with the potential for dependence and tolerance following repeated administration.
  • 4. OPIOID ANALGESICS- Classification Agonist Partial Agonist Mixed Agonist & antagonist Morphine Codeine Diacetylmorphine (Heroin) Pholcodine Pethidine Methadone Propoxyphene Levorphanol Tramadol Buprenorphine Meptazinol Nalbuphine Pentazocine Butorphanol
  • 5. Effects of different Opioid Receptor Stimulation
  • 7. Pharmacological actions - (CNS ) Analgesia: Strong analgesic Visceral pain is relieved better than somatic pain Degree of analgesia increases with dose Nociceptive pain is better relieved than Neurotic pain Associated reactions to pain are also relieved apprehension, fear and autonomic effects Tolerance to pain is better
  • 8. MORPHINE Analgesia action Two components spinal and supraspinal Inhibits release of excitatory transmitters from primary afferents at Substantia gelatinosa of dorsal horn Exerted through Interneurons gating of pain At supraspinal level in cortex, midbrain and medulla - alter processing and interpretation and send inhibitory impulses through descending pathway
  • 9. Pharmacological actions - (CNS ) Sedation: Drowsiness and indifference to surroundings Inability to concentrate and extravagant imagination colorful day dream Apparent excitement Larger doses produce sleep EEG resembles normal sleep Mood effects: In Normal persons calming effect, - mental clouding, - feeling of detachment, - lack of initiative etc. - unpleasant in absence of pain DYSHORIA But in persons with pain & addicts sense of wellbeing, pleasurable floating feelings kick EUPHORIA
  • 10. Pharmacological actions Neuro-endocrine: GnRH and CRH are inhibited FSH, LH and ACTH levels are lowered only short term tolerance develops Decrease in levels of Sex hormone and corticosteroids, but no infertility Increases ADH release oliguria CVS:NO DIRECT EFFECT ON HEART Vasodilatation histamine release, depression of vasomotor centre and directly on blood vessels decreasing the tone Cardiac work reduction due to consistent vasodilatation GIT: CONSTIPATION Due to direct action on intestine reducing propulsive movement, spasm of sphincters, decrease in all GIT secretions Smooth Muscles: Billiarycolic closure of sph. Of Oddi Bladder: Urinary urgency but difficulty Bronchi- Bronchospasm
  • 11. Pharmacological actions of Morphine Depression Stimulation Respiratory Centre- Both rate and depth of respiration are diminished. Dangerous in Head injury and asthmatics CTZ sensitize CTZ to vestibular and other impulses Temperature Regulating Centre Vagal Centre - Bradycardia Cough Centre Edinger Westphal Nucleus miosis Vasomotor Centre - high doses cause fall in BP Hippocampal cells convulsions (inhibition of GABA release
  • 12. Pharmacokinetics AbsorptionandDistribution Variable orally (usually not given orally 1st pass metabolism, given IM or IV) Widely distributed liver, spleen, kidney etc. Enters Brain slowly Readily crosses placental barrier dependence in fetus Metabolism In Liver by glucuronidation water soluble metabolites Morphine-6-glucuronide analgesic in renal failure prolong analgesia Morphine-3-glucoronide No analgesia neuroexcitatory Excretion Via Urine, Plasma t1/2 = 2-3 Hrs Action lasts for 4-6 Hrs Completely eliminated in 24 Hrs Preparation: 10, 15, and 20 mg. (IV: 2 10 mg)
  • 13. Adverse Effects 1. Respiratory Depression: Infant and Old 2. Vomiting 3. Sedation, Mental Clouding sometimes dysphoria 4. Hypotensive effect 5. Rise in Intracranial Pressure 6. Apnoea: Newborn 7. Urinary retention 8. Idiosyncrasy and allergy 9. Tolerance and dependence 10. Acute Morphine Poisoning: occurs if >50 mg (Lethal dose 250 mg) Gastric lavage with KMNO4, Specific antidote: Naloxone: 0.4 to 0.8 mg IV repeatedly in 2-3 minutes till respiration picks up
  • 14. Therapeutic uses Analgesic: 1. Long Bone Fracture 2. Myocardial Infarction 3. Terminal stages of cancer 4. Burn patients 5. Postoperative patients 6. Visceral pains pulmonary embolism, pleurisy, acute pericarditis 7. Biliary colic and renal colic 8. Obstetric analgesia 9. Segmental analgesia Other Therapeutic uses Preanesthetic Medication Balanced anesthesia and surgical analgesia Acute Left ventricular failure Cardiac asthma Cough not used but Codeine is used Diarrhoea colostomy - Loperamide, Diphenoxylate
  • 15. Contraindications 1. Two Extremes of Age 2. Bronchial asthma 3. Respiratory insufficiency empysema 4. Head Injury 5. Shock Hypotension 6. Undiagnosed acute abdomen 7. BHP 8. Renal Failure, Liver diseases and hypothyrodism 9. Unstable personalities