High-Potency Benzodiazepines: Recent Clinical Results

As high-potency benzodiazepines, essentially alprazolam, clonazepam, and lorazepam, have beenused to treat anxiety disorders for almost 2 decades, most efficacy and safety data appeared severalyears ago. The release of new formulations of 2 of them, clonazepam and alprazolam, invites reviewof these broadly effective anxiolytics. Clonazepam has recently become available in a lyophilizedwafer that disintegrates when exposed to saliva and enhances ease of administration without alteringits pharmacology, as shown by bioequivalence studies. Two U.S. multicenter trials carried out in the1990s, among others, have provided strong confirmatory evidence for the use of clonazepam in panicdisorder. Other recently published data on clonazepam pertain to its use as augmentation therapy withselective serotonin reuptake inhibitors and in the prevention of recurrences of major depressive disorder.A new, extended-release formulation of alprazolam now allows for once-daily rather than t.i.d. orq.i.d. dosing. With extended release, the blood drug concentrations of alprazolam remain within thetherapeutic window for several hours, which should reduce fluctuation in therapeutic effect and curbthe clock-watching phenomenon between doses. The literature concerning the use of this new formulationof alprazolam in panic disorder is reviewed.