CNS Depressants

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CNS Depressants

  1. 1. Central Nervous System DepressantsCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  2. 2. CNS Depressants Sedatives • Drugs that have an inhibitory effect on the CNS to the degree that they reduce: – Nervousness – Excitability – Irritability – without causing sleepCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  3. 3. CNS Depressants Hypnotics • Calm or soothe the CNS to the point that they cause sleepCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  4. 4. CNS Depressants Sedative-Hypnotics—dose dependent: • At low doses, calm or soothe the CNS without inducing sleep • At high doses, calm or soothe the CNS • to the point of causing sleepCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  5. 5. Sedative-Hypnotics: Barbiturates • First introduced in 1903, standard agents for insomnia and sedation • Habit-forming • Only a handful commonly used today due in part to the safety and efficacy of: BENZODIAZEPINESCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  6. 6. Sedative-Hypnotics: Barbiturates Four categories: • Ultrashort – mephobexital, thiamylal, thiopental • Short – pentobarbital, secobarbital • Intermediate – aprobarbital, butabarbital • Long – phenobarbitalCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  7. 7. Sedative-Hypnotics: Barbiturates Barbiturates have a very narrow therapeutic index. Therapeutic Index • Dosage range within which the drug is effective but above which is rapidly toxic.Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  8. 8. Sedative-Hypnotics: Barbiturates Mechanism of Action • Site of action: – Brain stem (reticular formation) – Cerebral cortex • By inhibiting GABA, nerve impulses traveling in the cerebral cortex are also inhibited.Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  9. 9. Sedative-Hypnotics: Barbiturates Drug Effects • Low doses: Sedative effects • High doses: Hypnotic effects (also lowers respiratory rate) Notorious enzyme inducersCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  10. 10. Sedative-Hypnotics: Barbiturates Therapeutic Uses • Hypnotics • Sedatives • Anticonvulsants • Surgical proceduresCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  11. 11. Sedative-Hypnotics: Barbiturates Side Effects Body System Effects CNS Drowsiness, lethargy, vertigo mental depression, coma Respiratory Respiratory depression, apnea, bronchospasms, coughCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  12. 12. Sedative-Hypnotics: Barbiturates Side Effects Body System Effects GI Nausea, vomiting, diarrhea Other Agranulocytosis, vasodilation, hypotension, Stevens-Johnson syndromeCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  13. 13. Sedative-Hypnotics: Barbiturates Toxicology • Overdose frequently leads to respiratory depression, and subsequently, respiratory arrest. • Can be therapeutic: – Anesthesia induction – Uncontrollable seizures: “phenobarbital coma”Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  14. 14. Sedative-Hypnotics: Barbiturates Drug Interactions • Additive effects: – ETOH, antihistamines, benzodiazepines, narcotics, tranquilizers • Inhibited metabolism: – MAOIs will prolong effects of barbiturates • Increased metabolism: – Reduces anticoagulant response, leading to possible clot formationCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  15. 15. CNS Depressants: Benzodiazepines Most frequently prescribed sedative-hypnotics • Most commonly prescribed drug classes • Favorable side effects • Efficacy • SafetyCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  16. 16. CNS Depressants: Benzodiazepines Classified as either: • Sedative-hypnotic or Anxiolytic (Medication that relieves anxiety)Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  17. 17. CNS Depressants: Benzodiazepines Sedative-Hypnotic Type • Long-Acting: – flurazepam (Dalmane), quazepam (Doral) • Short-Acting: – estazolam (Prosom), temazepam (Restoril), – triazolam (Halcion)Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  18. 18. CNS Depressants: Benzodiazepines Anxiolytic Type • alprazolam (Xanax) • chloridiazepoxide (Librium) • diazepam (Valium) • lorazepam (Ativan) • midazolam (Versed) zolpidem (Ambien) and zaleplon (Sonata) (nonbenzodiazepine hypnotic agents, share characteristics)Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  19. 19. CNS Depressants: Benzodiazepines Mechanism of Action • Depress CNS activity • Affect hypothalamic, thalamic, and limbic systems of the brain • Benzodiazepine receptorsCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  20. 20. CNS Depressants: Benzodiazepines Drug Effects • Calming effect on the CNS • Useful in controlling agitation and anxietyCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  21. 21. CNS Depressants: Benzodiazepines Therapeutic Uses • Sedation • Sleep induction • Skeletal muscle relaxation • Anxiety relief • Treatment of alcohol withdrawal • Agitation • Depression • Epilepsy • Balanced anesthesiaCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  22. 22. CNS Depressants: Benzodiazepines Side Effects • Mild and infrequent Headache Drowsiness Dizziness Vertigo Lethargy Paradoxical excitement (nervousness) “Hangover effect”Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  23. 23. CNS Depressants: Nursing Implications • Before beginning therapy, perform a thorough history regarding allergies, use of other medications,health history, and medical history. • Obtain baseline vital signs and I & O, including supine and erect BPs. • Assess for potential disorders or conditions that may be contraindications, and for potential drug interactions.Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  24. 24. CNS Depressants: Nursing Implications • Give 15 to 30 minutes before bedtime for maximum effectiveness in inducing sleep. • Most benzodiazepines (except flurazepam) cause REM rebound and a tired feeling the next day; use with caution in the elderly. • Patients should be instructed to avoid alcohol and other CNS depressants.Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  25. 25. CNS Depressants: Nursing Implications • Check with physician before taking any other medications, including OTC medications. • It may take 2 to 3 weeks to notice improved sleep when taking barbiturates. • Abruptly stopping these medications, especially barbiturates, may cause rebound insomnia.Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  26. 26. CNS Depressants: Nursing Implications • Safety is important – Keep side rails up – Do not permit smoking – Assist patient with ambulation (especially the elderly) – Keep call light within reach • Monitor for side effectsCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  27. 27. CNS Depressants: Nursing Implications • Monitor for therapeutic effects – Increased ability to sleep at night – Fewer awakenings – Shorter sleep induction time – Few side effects, such as hangover effects – Improved sense of well-being because of improved sleepCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.

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