A comparison of citalopram and paroxetine in the treatment of panic disorder: A randomized, single-blind study

Background: Serotonin Selective Re-uptake Inhibitors (SSRIs) are the drugs of choice for treating panic disorder (PD). In vitro studies have shown different pharmacodynamic profiles for SSRIs, but their clinical relevance is still unknown. Paroxetine, the SSRI with the strongest serotonergic effect, also shows significant cholinergic and noradrenergic activities. In this class of drugs, citalopram is the most selective for serotonin. We compared these two drugs and their effectiveness and tolerability in a sample of patients with PD in a two-month treatment course. Method: Fifty-eight patients with PD were randomly assigned to either the paroxetine or the citalopram treatment group in a single-blind, randomized design. Each patient was assessed at days 0, 7 and 60 by the Panic Associated Symptoms Scale (PASS), the Sheehan Disability Scale (SDS) and the Fear Questionnaire (FQ). Primary outcome measures were the percentage of patients free of panic attacks, anticipatory anxiety and phobic avoidance in the last week of the trial and the percentage of good responders, as defined by a reduction of at least 50% from baseline of both PASS and SDS global scores at day 60. Results: At day 60, 86% of patients receiving citalopram and 84% of those receiving paroxetine responded well to treatment. No significant differences between the two drugs were found. Both were well tolerated, although sexual side effects and weight gain were frequent. Anticipatory anxiety decreased significantly after the first week of treatment, and no initial worsening in the panic attacks was observed. Conclusion: Paroxetine and citalopram show similar anti-panic properties and a good tolerability profile. Our results support evidence that the serotonergic system plays a significant role in the anti-panic properties of these two SSRIs.