Therapeutic response to benzodiazepine in panic disorder subtypes

CONTEXT: This study makes a comparison between two subtypes of panic disorder regarding the clinical efficacy of clonazepam, a benzodiazepine. OBJECTIVES: To evaluate the clinical efficacy of clonazepam in a fixed dosage (2 mg/day), compared to placebo, in the treatment of panic disorder patients and to verify whether there are any differences in the responses to clonazepam between panic disorder patients with the respiratory and non-respiratory subtypes. TYPE OF STUDY: Randomized study with clonazepam and placebo. SETTING: Outpatient Anxiety and Depression Unit of the Institute of Psychiatry, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil. PARTICIPANTS: 34 patients with a diagnosis of panic disorder with agoraphobia, between 18 and 55 years old. PROCEDURES: Administration of clonazepam or placebo for 6 weeks, in panic disorder patients, after they were classified within two subtypes of panic disorder: respiratory and non-respiratory. MAIN MEASUREMENTS: Changes in the number of panic attacks in comparison with the period before the beginning of the study; Hamilton Anxiety Scale; Global Clinical Impression Scale; and Patient's Global Impression scale. RESULTS: In the group that received clonazepam, by the end of the 6th week there was a statistically significant clinical improvement, shown by the remission of panic attacks (p < 0.001) and decrease in anxiety (p = 0.024). In the group that received clonazepam there was no significant difference between the respiratory and non-respiratory subtypes of panic disorder, regarding the therapeutic response to clonazepam. CONCLUSION: Clonazepam was equally effective in the treatment of the respiratory and non-respiratory subtypes of panic disorder, suggesting there is no difference in the therapeutic response between the two subtypes