Name: Alprazolam (Xanax)
Class: Antianxiety-Sedative-Hypnotic Agent (Benzodiazepine)
Mechanism: Acts on BZD receptors closely coupled to GABAA receptors ® enhancement of GABA inhib. action via freq. of Cl- channel opening.
Absorption: Oral ® rapid absorption (large variability in indiv. responsiveness).
Dist.: Protein binding ³50%. CNS.
Metabolism.: Liver microsomal N-dealkylation/hydroxylation, then conjug ® inactive glucuronides. No induction of hepatic microsomal enzymes.
Excretion, t½: Urine—mostly Metabolismolized. Short—12-15 hr. Active Metabolismolites.
Toxicity/S.E.s: Acute—excessive depression of CNS fxns (drowsiness, sleep, confusion, disorientation, ataxia, slurred speech, nystagmus, mild amnesia, dementia). Early morning awakening, rebound insomnia. May also cause aggression, hyperactivity, delirium, insomnia. Large doses or mixture w/depressants (e.g., EtOH) may cause resp. depression, coma, hallucinations, nightmares, confusion. Chronic—impaired thinking/memory, weight gain/loss. Habituation & physical dependence ® w/drawal syndrome. Abrupt discontinuation ® risk for convulsion (greater risk than w/older BZDs). Metabolism. ¯ in elderly and by cimetidine. Overdose ® serious resp. depression (rarely fatal w/support). Psychological and physical dependence.
Utility: Panic/depression. Anxiety, insomnia, alcohol w/drawal. Sedation—all BZDs are DOCs for sedation.
Special Features: Newer BZD (shorter t½, greater potency).