7.b. sedative hypnotics

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Pharmacology
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7.b. sedative hypnotics

  1. 1. SEDATIVE- HYPNOTICS • SEDATIVE is a drug that reduces excitement and calms the person without inducing sleep. • HYPNOTIC is a drug that produces sleep resembling normal sleep. • ANTIANXIETY • ANXIETY is characterized by 1.Psychological symptoms: tension, fear, lack of concentration 2.Sympathetic and somatic symptoms: tachycardia, tremors, sweating, GI distress.
  2. 2. Normal sleep • PHASES OF SLEEP:TWO Phases 1. Rapid eye movement REM sleep where sympathetic system is activated. 2. Non REM sleep where parasympathetic is activated
  3. 3. SLEEP DISORDERS • SLEEP DISORDERS 1.Somnambulism 2.Sleep terror 3.teeth grinding 4.Sleep talking. All are treated with BDZ. 5.Insomnia (lack of sleep) sed.-hypnotics 6.Hypersomnia (excess sleep or narcolepsy)treated with amphetamine. 7.Nocturnal enuresis treated with antidepressants
  4. 4. CLASSIFICATION • BENZODIAZEPINES (BDZ) : Diazepam, Midazolam, Alprazolam. • BARBITURATES: LA: Phenobarbitone. SA: Pentobarbitone. USA: Thiopentone. • NON-BDZ HYPNOTICS: Zolpidem , Zopiclone. • MISCELLANEOUS: Melatonin, Chloral hydrate, Promethazine, Opioids, Neuroleptics,etc.
  5. 5. BENZODIAZEPINES • Binds to specific site on GABA-A-BDZ Receptor chloride channel complex. • Potentiates inhibitory effect of GABA. • Increase in frequency of opening of chloride channel. • Increase in chloride conductance. • Membrane hyperpolarization causing CNS Depression
  6. 6. PHARMACOKINETICS • Usually given by oral route or I.V & occasionally by rectal route in children. • IM absorption is irregular& erratic. • PPB is variable and they are widely distributed . • They are metabolised in liver and some produce active metabolites. • Metabolites are excreted in urine.
  7. 7. Clinical uses • DIAZEPAM: is used to 1. Control convulsions in status epilepticus (diazepam-drug of first choice) but not to treat epilepsy as there is rapid development of tolerance. 2. Treat Anxiety disorder 3. Treat Insomnia. 4. Skeletal muscle relaxant in spastic disorders 5. Treat Withdrawal effects of alcohol 6. As pre-anesthetic medication (diazepam) USES OF OTHER BDZ 1. Induction and short term anesthesia ( midazolam ) 2. As antidepressant ( Alprazolam)
  8. 8. Other drugs • ALPRAZOLAM: In addition to antianxiety action it also has antidepressant action. It is Short Acting (SA). • MIDAZOLAM: Is also SA with potent amnesic effect. Used as short term anesthetic and for induction anesthesia.
  9. 9. ADVERSE EFFECTS • BZD have wide margin of safety & well tolerated. • Common side effects : Drowsiness, Confusion, Blurred vision, Amnesia, disorientation, drug tolerance and drug dependance. • Withdrawal effects : Tremors, Insomnia, Restlessness, Nervousness & loss of appetite. • Teratogenic effect: (floppy baby syndrome) baby may have respiratory depression and hypotonia.
  10. 10. PHARMACOLOGICAL ACTIONS • SEDATION &HYPNOSIS: At present BDZ are preferred drugs for short term insomnia because- 1.have wide therapeutic index. 2.cause near normal sleep. 3.produce minimal hangover effect
  11. 11. BZD-ANTAGONIST FLUMAZENIL • It competitively reverses the effects of BZD agonists & also inverse agonists. ( Beta carbolines) • It is given IV route and has rapid onset of action. • It is used to reverse the BZD sedative effect during anesthesia and also in BZD over dose as antidote. • ADR: Nausea, Confusion, Dizziness & may precipitate withdrawal symptoms (anxiety convulsions).
  12. 12. BARBITURATES • It is not used as sedative –hypnotic as they posses: 1.low therapeutic index. 2.marked respiratory depression. 3.hangover effects. 4.high degree of tolerance and drug dependence. 5.there is no antidote available • Uses: • Thiopentone is used for induction anesthesia & diagnostic aid in Psychiatry & Narcoanalysis. • Phenobarbitone used as antiepileptic.
  13. 13. BARBITURATE POISONING- TREATMENT Maintain 1. Airway ,Breathing and Circulation. 2. Electrolyte balance. 3. Gastric Lavage. 4. Alkaline diuresis giving IV sodium bicarbonate. 5. Haemodialysis in severe cases. Note: No antidote available for barbiturates
  14. 14. NON BZD HYPNOTICS • ZOLPIDEM: act on BDZ receptors &produce hypnotic effect with minimal anticonvulsant and muscle relaxation. • USED for short term insomnia as it is short acting. • Well tolerated with minimal ADR like nausea, vomiting, confusion, headache. • Flumazenil antagonizes its action. • ZOPICLONE: SAME AS ABOVE .Both are given orally. • MELATONIN: is used for jet lag given orally in the evening.

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