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,
P.166
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. | |||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
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.