Wellbutrin XL, Wellbutrin SR
- Generic name: bupropion extended release
- Brand names: Wellbutrin XL, SR, Zyban
150 mg, 300 mg extended release tablets
150 mg, 200 mg sustained release tablets
- Pharmacologic category: Aminoketone antidepressant, Norepinephrine and Dopamine Reuptake Inhibitor
- FDA approved: August 29, 2003
- Manufacturer: GlaxoSmithKline
- Habit forming? No
- Pregnancy risk factor: C
Generic Wellbutrin SR, sWellbutrin XL
|Bupropion SR 150 mg
|Bupropion SR 150 mg
|Budeprion XL 300 mg
|Budeprion XL 300 mg
Wellbutrin XL (extended-release) is used to relieve mental depression. It is also used to prevent episodes of
seasonal affective disorder (form of depression occurring mainly during the autumn and winter months). This medication
effectively treats depression characterized by reduced energy, pleasure and interest, with low risk of weight gain sexual
This antidepressant is often prescribed for depression when selective serotonin reuptake inhibitors (SSRIs) or
tricyclic antidepressants (TCAs) cannot be used or are not effective.
Dosing: The starting dose is 150 mg per day, which your doctor may increase to the usual adult dose of 300 mg per day.
The maximum dosage is 450 mg per day. Always make sure that you take Wellbutrin XL as prescribed by your doctor.
Difference between Wellbutrin XL and SR
Wellbutrin XL contains the same active ingredient as Wellbutrin SR, but XL is formulated in an extended-release,
once-daily tablet. This means that with XL formulation, you can take one tablet in the morning, continue with your
daily activities, and not worry about remembering to take a second dose.
Both formulations are bioequivalent in terms of systemic exposure to bupropion, but differ in their pharmacokinetics and dosing.
Wellbutrin + SSRI combination
Although not an approved indication, the combination of Wellbutrin and either an SSRI or an SNRI is generally well
tolerated and can boost antidepressant response. Combining two antidepressants has become a common strategy in the treatment
of resistant depression. The results of clinical study have shown that when the patient fails to respond to an SSRI
or venlafaxine, an addition of Wellbutrin SR can increase the chances of response .
Wellbutrin appears to significantly affect dopaminergic neurotransmission and may help with fatigue and sexual
dysfunction induced by SSRIs of SNRIs. A study by Papakostas and associates examined the impact of bupropion vs SSRIs
on sleepiness and fatigue in patients with depression. The investigators pooled data from 6 double-blind, randomized
clinical trials and found greater improvements in fatigue scores among both bupropion-treated and SSRI-treated groups
than placebo-treated patients, and greater improvements in fatigue scores among bupropion-treated than SSRI-treated
Wellbutrin may reverse SSRI-induced sexual dysfunction due to its dopaminergic effect. In addition to the SSRI
produces an increase in desire to engage in sexual activity and frequency of engaging in sexual activity .
- Metabolism: Extensively metabolized by hydroxylation or oxidation in the liver. CYP2B6 is involved in formation
of hydroxybupropion (50% as potent as bupropion). The other 2 main metabolites are threohydrobupropion and
erythrohydrobupropion, which are 20% as potent as bupropion.
- Elimination half-life: about 21 hr, about 20 hr (hydroxybupropion), about 37 hr (threohydrobupropion),
and about 33 hr (erythrohydrobupropion).
- Excretion: 87% excreted in urine, 10% in feces, and 0.5% as unchanged drug.
- once a day dosage regimen
- low risk of sexual dysfunction : does not lower libido, produce impotence or impair orgasms
- low risk of weight gain
- decreased appetite and weight loss (however, may be a harmful effect for anorectic persons)
- low potential for triggering mania in the bipolar disorder
- frequently cause agitation, anxiety, and insomnia (addition of a sedative agent or discontinuation of therapy
may be required; gradual escalation of dose may minimize symptoms)
- risk of seizures
- risk of hypertension
- high potential for interactions; it is cytochrome P450-2D6 (CYP2D6) inhibitor
- attention-deficit/hyperactivity disorder (ADHD)
- depression associated with bipolar disorder (in combination with mood stabilizers)
- enhancement of weight loss
- combination of naltrexone plus bupropion is an experimental promising therapeutic option for treatment of obesity 
- augmenting a partial response to SSRIs
Mechanism of action
The mechanism of activity is not fully understood. It is a relatively weak inhibitor of the neuronal uptake
of norepinephrine and dopamine, and does not inhibit monoamine oxidase or the reuptake of serotonin. Metabolite inhibits the
reuptake of norepinephrine. The primary mechanism of action is thought to be dopaminergic and/or noradrenergic.
Reviews, Discussion Boards & Forums
- 1. U.S. FDA. Wellbutrin XL Prescribing Information
- 2. Labbate LA, Brodrick PS, Nelson RP, Lydiard RB, Arana GW. Effects of bupropion sustained-release on sexual functioning
and nocturnal erections in healthy men. J Clin Psychopharmacol. 2001 Feb;21(1):99-103.
- 3. Greenway FL, Fujioka K, Plodkowski RA, et al. Effect of naltrexone plus bupropion on weight loss in overweight and obese adults (COR-I): a multicentre, randomised, double-blind, placebo-controlled, phase 3 trial. Lancet. 2010 Aug 21;376(9741):595-605. PubMed
- 4. Bupropion Hydrochloride Extended-Release 300 mg Bioequivalence Studies FDA
Last updated: December 2013
- According to the FDA Budeprion XL 300 mg (manufactured by Impax Laboratories) is NOT therapeutically equivalent to Wellbutrin XL 300 mg4.
- Bupropion was first synthesized by Burroughs Research in 1966,
and patented by Burroughs-Wellcome (later Glaxo-Wellcome) in 1974.
It was approved by the FDA in 1989 and marketed under the name Wellbutrin as an antidepressant.
- Wellbutrin XL is the first and only once-daily norepinephrine
and dopamine reuptake inhibitor (NDRI) for the treatment of depression in adults.