Men with major depressive disorder appear to have significantly better sexual function with the selective norepinephrine-serotonin reuptake inhibitor duloxetine than with the selective serotonin reuptake inhibitor escitalopram, according to a presentation at the annual meeting of the American Psychiatric Association.

The eight-week study involved more than 680 patients. The sexual functioning assessment was part of a larger trial, the primary end point of which was to compare the onset of antidepressant efficacy between duloxetine and escitalopram. In this study, 42 percent of duloxetine patients met the definition of onset of efficacy compared with 35 percent of escitalopram patients.

Onset of efficacy was defined as at least a 20 percent decrease in Maier Subscale of the Hamilton Depression Rating Scale (HAM-D17) at week two and sustained throughout eight weeks of acute treatment. The study showed the onset of response to duloxetine to be at least as fast as that of escitalopram.

At the end of the acute period of the sexual functioning assessment (eight weeks), 37 percent of male patients treated with duloxetine reported a worsening in sexual functioning, 59 percent treated with escitalopram reported worsening, and 49 percent taking placebo experienced worsening, as measured by the Changes in Sexual Functioning Questionnaire (CSFQ).

In contrast, 36 percent of women treated with duloxetine reported a worsening of sexual functioning, 38 percent taking escitalopram reported worsening, and 26 percent taking placebo experienced worsening, as measured by the same questionnaire.

"Sexual dysfunction is common among patients with depression, affecting up to 64 percent of people with the illness," said Dr. Madelaine Wohlreich, a study co-author and medical advisor at Eli Lilly and Company. "Antidepressant treatment can also impact sexual functioning, so differences in the likelihood of sexual side effects are an important consideration for patients taking antidepressants."

Sexual dysfunction can be marked by a loss of sexual drive, interest, and/or performance. Loss of sexual functioning is a common side effect of antidepressant treatments, causing up to 70 percent of those who experience it to stop taking medication.

"When sexual dysfunction due to medication occurs, a person may be inclined to stop treatment, which can have a devastating impact on his or her illness," said Wohlreich. "In the case of depression, noncompliance with antidepressants can lead to a relapse."

At four and eight weeks, there was statistically significant worsening of sexual functioning for escitalopram compared to patients treated with placebo, while duloxetine was not statistically different from placebo at any time.

At eight weeks, categorical changes in sexual functioning differed significantly for men treated with duloxetine compared to men treated with escitalopram. There were no significant differences between medications in women.

Anorgasmia was the only treatment-emergent sexual adverse event reported statistically more frequently for duloxetine or escitalopram compared with placebo during the course of the study.

At the end of the study, there were no significant differences in discontinuation rates due to sexual side effects for those treated with duloxetine compared to those treated with escitalopram.

Adverse events causing discontinuation included erectile dysfunction, decreased libido, and orgasmic dysfunction including anorgasmia and ejaculation delay.