/publications/issue/2006/2006-08/2006-08-5752

GlaxoSmithKline's Wellbutrin XL

Author: Monica Holmberg

GlaxoSmithKline's Wellbutrin XL (bupropion hydrochloride (HCl) extendedrelease tablets) has received FDA approval for the prevention of seasonal affective disorder (SAD) in adults. Also known as major depressive disorder with a seasonal pattern, SAD is characterized by depressive symptoms that begin in the fall or winter and subside in the spring and summer. The disorder is believed to be linked to seasonal changes of light. Symptoms often include depressed mood, overeating, weight gain, lethargy, and increased sleep. An estimated 6% of American adults suffer from SAD.1

Wellbutrin XL is the first medication to be approved for the prevention of the symptoms of SAD. It is available as a convenient once-daily tablet.1,2 Its initial indication was for the treatment of major depressive disorder.2

Mechanism of Action

Although the exact mechanism of Wellbutrin XL is unknown, it is believed to exert noradrenergic and/or dopaminergic effects through weak inhibition of norepinephrine and dopamine uptake. Wellbutrin XL does not inhibit monoamine oxidase or the reuptake of serotonin.2

Clinical Trials

A total of 3 double-blind, placebo-controlled studies evaluated the efficacy of Wellbutrin XL for the prevention of SAD in adults with a history of the disorder. Treatment began in the autumn and was discontinued in the spring. The dose was initiated at 150 mg daily for 1 week and then increased to 300 mg daily. Patients who did not tolerate the 300-mg dose continued the 150-mg dose. The combined data for all 3 trials showed a significantly higher rate of depression-free patients in the Wellbutrin XL group: 84.3% in the active group and 72.0% in the placebo group.1,2

Dosing

As in the clinical trials, the target treatment period for SAD is autumn through spring. Treatment should be initiated in the autumn at 150 mg once daily for 1 week. If the 150-mg dose is tolerated, it may be increased to 300 mg daily. Total daily doses above 300 mg have not been studied. The dose should be tapered to 150 mg daily for 2 weeks prior to the discontinuation of treatment in the spring.2

Safety

A worsening of depression or suicidal ideation while taking antidepressants has been noted in both adult and pediatric populations. Of specific concern, some short-term studies of antidepressants in children and adolescents with major depressive disorder have shown an increased risk for suicidality. Although Wellbutrin XL is indicated only for treatment in adults 18 years of age and older, all patients using Wellbutrin XL should be monitored for any changes in mood or behavior.1,2

Wellbutrin XL is contraindicated in patients with a current diagnosis of or history of seizure disorder, bulimia, or anorexia nervosa. Patients currently taking any other formulations of bupropion or with an allergy to bupropion should not use Wellbutrin XL. Concurrent use of Wellbutrin XL and monoamine oxidase inhibitors (MAOIs) is contraindicated. Prescribers should allow at least 14 days between discontinuing a MAOI and initiating treatment with Wellbutrin XL. Wellbutrin XL is contraindicated in patients abruptly discontinuing alcohol or sedatives such as benzodiazepines.2 Wellbutrin XL should be used cautiously in patients with renal and hepatic impairment. Dose and frequency adjustments may be necessary, and clinical outcomes should be monitored closely for both efficacy and toxicity.2

Some patients using Wellbutrin XL have experienced restlessness, agitation, anxiety, and insomnia.2 In clinical trials, the most common side effects were dry mouth, nausea, constipation, and flatulence.1

Patient Counseling

Patients should swallow Wellbutrin XL tablets whole, without crushing, chewing, splitting, or cutting them. The tablets should be taken at approximately the same time every day and may be taken with or without food. If a dose is missed, the patient should wait and take the next dose at the next scheduled time. Patients should contact their doctor immediately if signs of a severe allergic reaction, seizure, or unusual thoughts occur.2

Monica Holmberg, PharmD Dr. Holmberg is a pharmacist with Phoenix Children's Hospital, Phoenix, Ariz.

For a list of references, send a stamped, self-addressed envelope to: References Department, Attn. A. Rybovic, Pharmacy Times, Ascend Media Healthcare, 103 College Road East, Princeton, NJ 08540; or send an email request to: arybovic@ascendmedia.com