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New Study Compared Sexual Functioning of Patients Treated with Wellbutrin XL (bupropion HCl extended-release tablets) Versus Effexor XR (venlafaxine HCl extended-release tablets)


Data Showed Venlafaxine XR Worsens Sexual Function

LAS VEGAS, November 10, 2005 Sexual functioning worsened in patients with major depressive disorder treated with venlafaxine XR as compared to patients treated with Wellbutrin XL, according to the results of a new study presented today at the 18th Annual U.S. Psychiatric & Mental Health Congress.

This is the first head-to-head 12-week study to compare the impact on sexual functioning of Wellbutrin XL, the once-daily norepinephrine and dopamine reuptake inhibitor (NDRI), to the serotonin and norepinephrine reuptake inhibitor (SNRI) venlafaxine XR among patients with major depressive disorder. Wellbutrin XL has been previously shown to have a lower risk of sexual dysfunction as compared to the serotonin reuptake inhibitor (SSRI) Lexapro (escitalopram oxalate) in similarly designed studies.

The study showed statistically significant worsening in sexual functioning among patients with major depressive disorder who were treated with venlafaxine XR, regardless of baseline sexual function and despite improvement of depressive symptoms. Venlafaxine XR negatively impacted multiple domains of sexual functioning as compared to Wellbutrin XL, including desire/interest, desire/frequency and orgasm. Sexual function was not impacted by Wellbutrin XL.

Up to 14 million adults are affected by major depressive disorder, commonly referred to as depression, in any given year. In the U.S., 10 percent of women and 4 percent of men over the age of 18 now take antidepressants. But, of these, as many as 59 percent may experience sexual side effects as a result of their medication.

People taking antidepressants are often reluctant to discuss sexual side effects with their doctor and many believe that all treatments are the same, said Anita Clayton, MD, Universityof Virginia, Charlottesville, VA, and lead author of the study. This trial provides comparative data on which to base treatment decisions for those patients who express concerns about or experience sexual side effects.

About the Study

This study was a 12-week,randomized, double-blind, multicenter trial comparing Wellbutrin XL and venlafaxine XR in 342 adult outpatients with moderate to severe major depressive disorder with regard to sexual functioning, efficacy and safety. Patients received escalating doses of either Wellbutrin XL (150-450 mg/day) or venlafaxine XR (75-225 mg/day).

Overall sexual functioning was measured by the vector of mean change in the Changes in Sexual Functioning Questionnaire (CSFQ-C) total score across weeks five, six, nine and 12, using mixed model repeated measures technique.

Efficacy measures included the 17-item Hamilton Depression Rating Scale (HAMD-17), administered via interactive voice response, Clinical Global Impression of Severity (CGI-S), and Clinical Global Impression of Improvement (CGI-I). The Frequency and Intensity of Side Effect Rating (FISER) and Global Rating of Side Effect Burden (GRSEB) scales were used in addition to routine safety evaluations at clinic visits.

General Safety and Tolerability

With the exception of venlafaxine XRs negative impact on sexual functioning, Wellbutrin XL and venlafaxine XR were generally well tolerated. General adverse events were similar to those previously reported for both treatments. Of the most common adverse events, diarrhea, decreased appetite, fatigue, somnolence, sedation, and yawning occurred more frequently (by a factor of 2 or more) in the venlafaxine XR group relative to Wellbutrin XL, while nasopharngitis, anxiety and irritability occurred more frequently in the Wellbutrin XL group relative to venlafaxine XR.

Important Safety Information

Wellbutrin XL is not for everyone. There is a risk of seizure when taking Wellbutrin XL so people who have had a seizure or eating disorder, or have abruptly stopped using alcohol or sedatives, should not take Wellbutrin XL. People should not use Wellbutrin XL with monoamine oxidase inhibitors (MAOIs), or medicines that contain bupropion. When used with a nicotine patch or alone, there is a risk of increased blood pressure, sometimes severe. To reduce risk of serious side effects, people should tell their doctor if they have liver or kidney problems. Other side effects may include weight loss, dry mouth, nausea, difficulty sleeping, dizziness, or sore throat.

Wellbutrin XL is approved only for adults 18 years and over. In some children and teens, antidepressants increase suicidal thoughts or actions. Whether or not a person is taking antidepressants, they or their family should call the doctor right away if they have worsening depression, thoughts of suicide, or sudden or severe changes in mood or behavior, especially at the beginning of treatment or after a change in dose (see Patient Information: What is important information I should know and share with my family about taking antidepressants?, available at


GlaxoSmithKline, one of the worlds leading research-based pharmaceutical and healthcare companies, is committed to improving the quality of human life by enabling people to do more, feel better and live longer. GlaxoSmithKline has U.S.operations in Philadelphia and Research Triangle Park, N.C.

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Please consult full prescribing information available at or by contacting Robin Gaitens at GlaxoSmithKline at 919-483-2839.


Effexor XR is a registered trademark of Wyeth Pharmaceuticals, Inc. Lexapro is a registered trademark of Forest Laboratories, Inc.


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