Pharmacy Author: Omudhome Ogbru, PharmD
Pharmacy and Medical Editor: Jay W. Marks, MD

GENERIC NAME: bupropion

BRAND NAME: Wellbutrin, Wellbutrin SR, Wellbutrin XL, Zyban

DRUG CLASS AND MECHANISM: Bupropion is an antidepressant medication that affects chemicals within the brain that nerves use to send messages to each other. These chemical messengers are called neurotransmitters. Many experts believe that depression is caused by an imbalance among the amounts of neurotransmitters that are released. Nerves, in a process referred to as reuptake, may recycle released neurotransmitters. Bupropion works by inhibiting the reuptake of dopamine, serotonin, and norepinephrine; an action that results in more dopamine, serotonin, and norepinephrine to transmit messages to other nerves. Bupropion is unique and unlike other antidepressants in that its major effect is on dopamine, an effect that is not shared by the selective serotonin reuptake inhibitors or SSRIs [for example, paroxetine (Paxil), fluoxetine (Prozac), sertraline (Zoloft)] or the tricyclic antidepressants or TCAs [for example, amitriptyline (Elavil), imipramine (Tofranil), desipramine (Norpramin)]. The FDA approved bupropion in December 1985.

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes

PREPARATIONS: Tablets: 75, 100, and 150 mg. Sustained Release tablets: 100, 150, and 200 mg. Extended Release tablets: 150 and 300 mg.

STORAGE: Tablets should be kept at room temperature, 15-25°C (59-77°F).

PRESCRIBED FOR: Bupropion is used for the management of major depression and seasonal affective disorder (depression that occurs primarily during the fall and winter). It is also prescribed for smoking cessation.

DOSING: Bupropion usually is given in one, two or three daily doses. For immediate-release tablets, no single dose should exceed 150 mg and each dose should be separated by 6 hours.

For depression the recommended dose of immediate-release tablets is 100 mg 3 times daily (300 mg/day); maximum dose is 450 mg daily. The initial dose is 100 mg twice daily. The dose may be increased to 100 mg 3 times daily after three days.

The initial dose of sustained-release tablets is 150 mg daily; target dose is 150 mg twice daily; maximum dose is 200 mg twice daily.

The initial dose of extended-release tablets is 150 mg daily; target dose is 300 mg daily; maximum dose is 450 mg daily. Extended release tablets are administered once daily.

When used for smoking cessation, bupropion usually is started as 150 mg once daily for three days, and then the dose is increased if the patient tolerates the starting dose. Smoking is discontinued two weeks after starting bupropion therapy.

Wellbutrin SR is given as two daily doses. Wellbutrin XL is given as one dose daily.

DRUG INTERACTIONS: Bupropion should be used cautiously in patients receiving drugs that reduce the threshold for seizures. Such drugs include prochlorperazine (Compazine), chlorpromazine (Thorazine), and other antipsychotic medications of the phenothiazine class. Additionally, persons who are withdrawing from benzodiazepines [for example, diazepam (Valium), alprazolam (Xanax)] are at increased risk for seizures.

Carbamazepine (Tegretol) may reduce the effect of bupropion by reducing the blood concentration of bupropion. Monamine oxidase inhibitors should not be combined with bupropion because of the risk of severe reactions. At least 14 days should elapse between discontinuation of an MAOI and initiation of bupropion. Bupropion may affect the action of warfarin (Coumadin).

PREGNANCY: There are no adequate studies of bupropion in pregnant women. In one study, there was no difference between bupropion and other antidepressants in the occurrence of birth defects. Bupropion should only be used in pregnancy if the benefit outweighs the potential risk.

NURSING MOTHERS: Bupropion is secreted in breast milk.

SIDE EFFECTS: The most common side effects associated with bupropion are agitation, dry mouth, insomnia, headache, nausea, constipation, and tremor. In some people, the agitation or insomnia is most marked shortly after starting therapy. Some patients may experience weight loss. Uncommonly, patients may experience manic episodes or hallucinations. Four of every 1000 persons who receive bupropion in doses less than 450 mg/day experience seizures. When doses exceed 450 mg/day, the risk increases ten-fold. Other risk factors for seizures include past injury to the head and medications which can lower the threshold for seizures. (See drug interactions.)

Antidepressants increased the risk of suicidal thinking and behavior (suicidality) in short-term studies in children and adolescents with depression and other psychiatric disorders. Anyone considering the use of bupropion or any other antidepressant in a child or adolescent must balance this risk with the clinical need. Patients who are started on therapy should be closely observed for clinical worsening, suicidality, or unusual changes in behavior.

Additional drug information: Zyban (bupropion hydrochloride) FDA approved labeling at RxList.
http://www.rxlist.com/zyban-drug/article.htm

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