Wellbutrin IR, SR, XL Fact Sheet
GlaxoSmithKline; available as generic bupropion IR and SR; generic bupropion XL received approval in 2006.
Major Depressive Disorder
- Prevention of Seasonal Affective Disorder (Wellbutrin XL only)
- Smoking cessation (Zyban only)
Wellbutrin is chemically unrelated to SSRI, tricyclic or other known antidepressants; mediated by noradrenergic and/or dopaminergic mechanisms.
- XL: 150 mg and 300 mg tablets
- SR: 100 mg, 150 mg, and 200 mg film-coated tablets
- IR (original immediate release version): 75 mg and 100 mg tablets
- Zyban: 150 mg purple tablets
- XL beginning dose: 150 mg QAM; may increase to usual dose of 300 mg QAM if adequately tolerated after at least 4 days; maximum dose 450 mg QAM.
- SR beginning dose: Start at 100 mg QAM, and gradually titrate to usual dose of 150 mg BID; maximum dose 200 mg BID.
- Zyban: Begin two weeks before quit date at 150 mg QD, increase to 150 mg BID after 3 days.
- Dose must be reduced in patients with kidney or liver impairment.
Most common (for Wellbutrin SR 300 mg/day) are: anorexia, dry mouth, rash, sweating, tinnitus, and tremor (>5% and > twice placebo rate).
- Seizure risk at 300 mg/day or less is 0.1%, similar to risk with other ADs; seizure risk at 450 mg/day is about 0.4%, and at 600 mg/day almost 4%.
- Black Box Warning: In clinical trials, SSRIs and SNRIs increased the risk of suicidality in children (from 2% to 4%). No actual suicides occurred in these trials.
- Pregnancy Risk Category C
Luvox (fluvoxamine) inhibits the metabolism of bupropion, possibly increasing levels.
- Wellbutrin can increase levels of a variety of antidepressants, most notably Effexor.
All four formulations are equally effective, and there is no demonstrated difference in risk of seizure; XL has a slight convenience advantage for the patient (once-daily dosing).
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