Benzodiazepines

Authors: Flaherty, Alice W.; Rost, Natalia S.

Title: Massachusetts General Hospital Handbook of Neurology, The, 2nd Edition

Copyright 2007 Lippincott Williams & Wilkins

> Table of Contents > Drugs > Benzodiazepines

Benzodiazepines

A. Indications

Anxiolysis, sedation, muscle spasms, seizures.

B. Time course

Diazepam has the shortest onset; oxazepam the shortest duration. Short-acting drugs, e.g., alprazolam, can cause rebound anxiety.

C. Mechanism

Benzodiazepines are GABA-A receptor agonists.

D. Side effects

Respiratory depression, hypotension. Mildly teratogenic during first trimester only. Although shorter acting ones, e.g., alprazolam,

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are less sedating, they cause more rebound and withdrawal. Do not use them as analgesics; they can worsen pain.

  • Withdrawal: Can occur after prolonged use, so taper slowly. Sx are similar to alcohol withdrawal and can be life threatening.

  • Overdose: Flumazenil partly reverses effects but probably not the respiratory depression, and it may trigger seizures. Try 0.2 mg (2 mL) IV over 30 sec, then 0.3 mg q min to effect, max. of 3 mg (10 doses). Since half-life is 15 min-2.5 h, consider IV drip of 1 mg/h.

Table 46. Benzodiazepine half-life and metabolism.

Generic Name Brand Name Half-Life PO Dose (mg) Liver Metab?
Alprazolam Xanax 12 h 0.25-0.5 tid
Clonazepam Klonopin 18-48 h 0.25-2 tid Yes
Chlordiazepoxide Librium 24 h 5-25 tid/qid Yes
Diazepam Valium 20-80 h 2-10 bid/qid Yes
Lorazepam Ativan 8-20 h 0.5-2 q6-8h
Oxazepam Serax 8 h 10-15 tid/qid

E. Comorbid dz

  • Liver failure: In cirrhotics and the elderly, benzodiazepines metabolized in the liver (e.g., diazepam) can linger for weeks. Lorazepam or oxazepam, metabolized primarily in the kidney, are preferred. If pt has hepatic encephalopathy, avoid benzodiazepines completely; use narcotics if sedation is required.

  • Kidney failure: Use lorazepam, oxazepam (no active metabolites).

  • The elderly: Oxazepam is usually better tolerated than lorazepam.



The Massachusetts General Hospital. Handbook of Neurology
The Massachusetts General Hospital Handbook of Neurology
ISBN: 0781751373
EAN: 2147483647
Year: 2007
Pages: 109

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