Paroxetine augmentation in patients with generalised social anxiety disorder, non-responsive to mirtazapine or placebo.

Objectives: The aim of the study was to investigate if combination of mirtazapine with paroxetine causes a greater therapeutic effect and less sexual side effects than paroxetine monotherapy in social anxiety disorder (SAD).

Methods: Twenty one patients with generalised SAD, non-responsive to a 12 week trial with mirtazapine and 22 patients, non-responsive to placebo received paroxetine (20-40 mg) in addition to their double-blind treatment with mirtazapine or placebo for another 12 weeks. The Liebowitz Social Anxiety Scale (LSAS) and the Clinical Global Impression-Improvement (CGI-I) scale were used to measure efficacy. Sexual functioning was assessed by the Arizona Sexual Experiences Scale (ASEX).

Results: Both treatments showed a significant LSAS reduction and their response rates (based on LSAS reduction ≥ 40% and CGI-I ≤ 2) were similar (paroxetine and mirtazapine: 52.4%, paroxetine and placebo: 59.1%). Sexual dysfunction (based on ASEX ≥ 19) was found in half of patients treated with paroxetine and placebo, and in 38% of patients treated with paroxetine and mirtazapine.

Conclusion: The present study did not find support for a greater efficacy of combination pharmacotherapy in SAD, however results suggest that combination of paroxetine with mirtazapine might cause less sexual dysfunction than treatment with paroxetine alone.