Paroxetine, but not Vortioxetine, Impairs Sexual Functioning Compared With Placebo in Healthy Adults: A Randomized, Controlled Trial
Authors: Jacobsen Paula , Zhong Wei , Nomikos George , Clayton Anita 
Published: August 2019

Abstract

Introduction
Sexual dysfunction is prevalent among patients with depression, but assessment of treatment-emergent sexual dysfunction (TESD), a common side effect of antidepressants, can be confounded by the treatment of depressive symptoms in some patients.

Aim
To evaluate sexual functioning in healthy volunteers administered vortioxetine compared with paroxetine, an antidepressant known to cause sexual dysfunction, and placebo.

Methods
This phase 4, multicenter, randomized, double-blind, placebo-controlled, 4-arm, fixed-dose, head-to-head study compared sexual functioning in healthy volunteers administered vortioxetine (10 and 20 mg once daily [QD]), paroxetine (20 mg QD), or placebo for 5 weeks. Approximately equal numbers of men and women ages 18–40 years with normal sexual functioning (self-reported Changes in Sexual Functioning Questionnaire Short-Form [CSFQ-14] score &gt; 47 for men; &gt; 41 for women) were enrolled. Two modified full analysis sets adjusting for treatment non-compliance were prespecified.

Main Outcome Measure
The primary endpoint was change in CSFQ-14 total score for vortioxetine (10 and 20 mg) vs paroxetine after 5 weeks. Additional endpoints included CSFQ-14 change scores vs placebo, CSFQ-14 subscales, and patient global impression.

Results
Of the 361 subjects enrolled (mean age, 28.4 years), approximately 57% were white, 34% black/African American, and 4% Asian. Vortioxetine 10 mg was associated with significantly less TESD than paroxetine (mean difference, +2.74 points; P = .009). Although vortioxetine 20 mg was associated with numerically less TESD than paroxetine (mean difference, +1.05 points), this difference did not reach statistical significance. Non-compliance appeared to influence results, particularly the paroxetine and vortioxetine 20 mg arms. Paroxetine, but not vortioxetine, was associated with statistically significantly more TESD vs placebo. Vortioxetine also had better outcomes than paroxetine in the 3 phases and 5 dimensions of sexual functioning measured by CSFQ-14.

Clinical Implications
These data establish that vortioxetine is associated with less TESD than paroxetine in healthy individuals, suggesting that vortioxetine may be a drug of choice in managing depressive disorders when sexual functioning is a concern.

Strengths & Limitations
Conducting the study in healthy adults mitigated the risk of an underlying condition (eg, depression) confounding the results. Assay sensitivity was demonstrated by statistically significant TESD with paroxetine vs placebo. The single comparator, paroxetine, and short study duration limit the generalizability of these results.

Conclusion
Vortioxetine is associated with less TESD than paroxetine in healthy adults across all phases and dimensions of the sexual response cycle. Vortioxetine was not significantly different from placebo on sexual functioning; however, the difference was significant between paroxetine and placebo, validating study results.