To describe with prospective methodology the therapeutic response to clonazepam or paroxetine in a 3-year treatment of panic disorder (PD).

A total of 120 PD outpatients (DSM-IV) were openly treated with clonazepam or paroxetine for 8 weeks. Those who responded entered a 3-year follow-up. Demographic and clinical features were compared in the two groups.

Efficacy was evaluated by Intent to treat, last value carried forward. The Hamilton Scale for Anxiety (HAMA) did not differ between the groups at baseline and during the first two months. In the acute treatment phase and at the end of the long-term follow-up both groups had a significant and similar response - 86.8% of the clonazepam group and 73.0% of the paroxetine group had a complete remission of panic attacks. The mean dose for clonazepam was 1.9 ± 0.2 mg/day and for paroxetine 33.8 ± 9.8 mg/day. There was no difference in the scale scores, and the reduction in panic attacks from baseline to end-point did not differ significantly between the groups. The most common adverse events during treatment were tremor/shaking, nausea/vomiting, sexual dysfunction and appetite/weight change in the paroxetine group and drowsiness, sexual dysfunction and memory/concentration complains in the clonazepam group.

PD patients using clonazepam or paroxetine had an equivalent response during acute and long term treatment. The patients using clonazepam had significantly less side effects than the paroxetine group.

Acknowledgements: Brazilian Council for scientific and technological development (CNPq).

Grant: 554411/2005-9.