Buspirone, a novel nonbenzodiazepine anxiolytic.

The chemistry, pharmacology, pharmacokinetics, clinical efficacy, adverse effects, dosage, administration, and availability of buspirone hydrochloride, a novel nonbenzodiazepine anxiolytic, are reviewed. Buspirone hydrochloride is an azaspirodecanedione anxiolytic. The exact mechanism of its anxiolytic action is unknown. It does not appear to influence the benzodiazepine-gamma-aminobutyric acid-chloride ionophore complex as the benzodiazepines do. It antagonizes striatal-dopamine autoreceptors, and it may act as a midbrain modulator exerting selective anxiolytic activity. Buspirone is rapidly absorbed after oral administration. Administration with food appears to slow the rate of drug absorption and increase the amount of unchanged drug reaching the systemic circulation. Buspirone's elimination half-life is 2.5-3 hours. It is extensively metabolized, with less than 1% of an administered dose excreted as unchanged drug. The contribution of its metabolites to its anxiolytic effects is unknown. Buspirone has been shown to be as effective as diazepam and clorazepate and more effective than placebo in the treatment of generalized anxiety. Buspirone lacks the sedative, muscle relaxant, and anticonvulsive effects of the benzodiazepines. Its adverse effects are minimal, with dizziness, nervousness, and headaches as the most common side effects. Buspirone does not impair driving skills, interact with alcohol or concomitant medications, or produce physiologic dependence. It appears to have little potential for abuse. The average daily adult dose is 15-20 mg. Buspirone hydrochloride is an effective drug in the treatment of generalized anxiety disorder that is comparable with the conventional benzodiazepine anxiolytics.