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Wellbutrin IR, SR, XL Fact Sheet

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Medication Name (brand): 
Wellbutrin IR, SR, XL / Zyban
Medication Name (clinical): 

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.

  • Supplied in:

  • 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.

Side Effects: 
  • 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

Drug-drug Interactions: 
  • 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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