An open clinical trial of clonazepam in the treatment of patients with recurrent panic attacks

Clomipramine and clonazepam increase cholecystokinin levels in rat ventral tegmental area and limbic regions

Recent reports suggest that a cholecystokinin (CCK)-related dysfunction may be a target by which drugs can modulate anxiety and panic disorders. In the present study, effects of subchronic (14 days) treatment with the monoamine uptake inhibitors nortriptyline (30 mumol/kg per day), amitriptyline (29 mumol/kg per day), clomipramine (32 mumol/kg per day) and alaproclate (39 mumol/kg per day), as well as with the benzodiazepine clonazepam (0.25 mumol/kg per day), on rat brain levels of CCK- and substance P-like immunoreactivity, were compared. The drugs were administered by continuous s.c. infusion using implanted osmotic pumps. The plasma concentrations of the monoamine uptake inhibitors were similar after 1 and 2 weeks of treatment, indicating that steady-state plasma levels had been reached during the first week. Treatment with clomipramine or clonazepam increased the CCK-like immunoreactivity level in the ventral tegmental area (by 64.4 +/- 28.8% and 105.1 +/- 28.8%, respectively) and in the cingulate cortex (by 30.3 +/- 10.1% and 36.0 +/- 11.8%, respectively) (P < 0.05 or P < 0.01). Clomipramine also significantly increased the CCK-like immunoreactivity level in the periaqueductal grey by 85.1 +/- 29.7%. Neither nortriptyline nor amitriptyline or alaproclate produced any significant alterations in the CCK- or substance P-like immunoreactivity levels in the areas examined. The present results may suggest that an altered utilization of CCK in limbic circuits could be of importance for the well documented clinical effect of clomipramine and clonazepam in panic disorders.

Profiles of the antipanic compounds, triazolobenzodiazepines and phenelzine, in two animal tests of anxiety

Two animal tests of anxiety (the elevated plus-maze and the social interaction test) were used to investigate the effects of several antipanic agents. In the elevated plus-maze, the triazolobenzodiazepines adinazolam (2 and 5 mg/kg) and alprazolam (1 mg/kg), tested after 5 days of pretreatment, demonstrated significant anxiolytic effects, while phenelzine (9 mg/kg), after 21 days of pretreatment, demonstrated nonsignificant anxiolytic effects. In the social interaction test, the triazolobenzodiazepines generally did not produce an anxiolytic profile, and phenelzine even revealed significant anxiogenic activity. The antipanic agents therefore distinguish between the two tests of anxiety. The lack of a strong anxiolytic profile with these agents in both tests lends support to the distinction between generalized anxiety and panic disorder.

The role of central- and peripheral-type benzodiazepine receptors in anxiolytic-agent augmentation of NaCl solution intake: effects of clonazepam and Ro 5-4864

Two 1,4 benzodiazepines bind preferentially to the central- and peripheral-type benzodiazepine receptor in the brain, clonazepam and Ro 5-4864, respectively. They were administered to rats to determine if the relation between known anxiolytic action and efficacy in augmenting NaCl solution ingestion in rehydrating rats would remain the case for these prototypic agents. Clonazepam (0.062-32.0 mg/kg, PO) was highly potent and efficacious and increased 1.5% NaCl solution intake in a dose-related fashion. Water intake could also be increased, but to a relatively minor degree. Ro 5-4864 (4-8 mg/kg, IP) did not affect 1.5% NaCl solution ingestion, nor did this dose range suppress the augmenting effect of clonazepam (0.5-2.0 mg/kg, PO) on the solution intake. Since clonazepam does, and Ro 5-4864 does not, possess punishment-attenuation properties in other tests, drug augmentation of NaCl solution ingestion by rehydrating rats continues to correlate well with known anxiolytic action.