Bupropion



Bupropion 880
Photo by: Eric Simard

Definition

Bupropion is an antidepressant drug used to elevate mood and promote recovery of a normal range of emotions in patients with depressive disorders. In addition, bupropion is used to as an aid in smoking cessation treatment. In the United States, bupropion is sold as an antidepressant under the brand name Wellbutrin. As a smoking cessation treatment, the drug is marketed under the brand name Zyban.

Purpose

Bupropion is principally known as an antidepressant drug used to promote recovery of depressed patients. It also has therapeutic uses in smoking cessation treatment, panic disorder , and attention-deficit/hyperactivity disorder (ADHD).

Description

Bupropion is a non-tricyclic antidepressant drug. Tricyclic antidepressants, which have a three-ring chemical structure, may cause troublesome side effects, including sedation, dizziness, faintness, and weight gain. Until the 1980s, such drugs were the mainstay of the pharmacological treatment of depression. Bupropion was one of the first antidepressants with a significantly different chemical structure to be developed by pharmaceutical researchers seeking drugs effective in treating depression but without the unwanted actions of the tricyclic antidepressants.

The exact way that bupropion works in the brain is not understood. Its mechanism of action appears to be different from that of most other antidepressant drugs, although bupropion does act on some of the same neurotransmitters and neurotransmission pathways. Neurotransmitters are naturally occurring chemicals that regulate the transmission of nerve impulses from one cell to another. Mental well-being is partially dependent on maintaining the proper balance among the various neurotransmitters in the brain. Bupropion may restore normal emotional feelings by counteracting abnormalities of neurotransmission that occur in depressive disorders.

In contrast to the drowsiness frequently caused by other antidepressants, bupropion is a mild stimulant. Bupropion is also less likely to cause weight gain and adverse effects on blood pressure and the heart. However, it is more likely to trigger epileptic seizures .

Recommended dosage

The usual adult dose of bupropion (Wellbutrin) is 100 mg, taken three times per day, with at least six hours between doses. The extended release form of the drug (Wellbutrin SR) is taken as 150 mg twice a day with at least eight hours between doses. For smoking cessation, bupropion (Zyban) is taken as 150-mg extended release tablets twice a day, with at least eight hours between doses. Bupropion treatment should be started at a lower dose, then gradually increased to a therapeutic dosage, as directed by the physician. Generally, the total dosage should not exceed 300 mg per day, except as directed by the physician.

The therapeutic effects of bupropion, like other antidepressants, appear slowly. Maximum benefit is often not evident for several weeks after starting the drug. People taking bupropion should be aware of this and continue taking the drug as directed even if they do not see immediate improvement in mood.

Since higher doses of bupropion increase the risk of seizures, no more than 150 mg should be given at any one time, and the total daily dosage should not be increased by more than 100 mg every three days. Increasing the dosage gradually also minimizes agitation, restlessness, and insomnia that may occur.

Healthy elderly patients do not appear to be more sensitive to side effects of bupropion than younger adults and do not require reduced doses. Certain medical conditions, especially liver and kidney disease, may necessitate dose reduction. Although bupropion has been taken by children and adolescents under age 18, it has not been systematically studied in these age groups.

Precautions

Bupropion is more likely to trigger epileptic seizures than other antidepressants. The drug should not be given to patients who have a history of epilepsy, take other medication to help control seizures, or have some other condition associated with seizures, such as head trauma or alcoholism. Nevertheless, in fewer than 1% of healthy people taking bupropion at the recommended dose have seizures. The possibility of seizures is increased at higher doses and following a sudden increase in dose. Patients should minimize alcohol intake while taking bupropion, since alcohol consumption increases the chance of seizures.

Because of the possibility of overdose, potentially suicidal patients should be given only small quantities of the drug at one time. Increases in blood pressure have occurred in patients taking bupropion along with nicotine treatment for smoking cessation. Monitoring blood pressure is recommended in such cases. Excessive stimulation, agitation, insomnia, and anxiety have been troublesome side effects for some patients, especially when treatment is first begun or when the dose is increased. Such adverse effects may be less intense and less frequent when the dose is increased gradually.

It has not been determined whether bupropion is safe to take during pregnancy. Pregnant women should take bupropion only if necessary. The drug is secreted in breast milk. Women taking bupropion should consult their physicians about breast-feeding.

Side effects

Bupropion is a mild stimulant and may cause insomnia, agitation, confusion, restlessness, and anxiety. These effects may be more pronounced at the beginning of therapy and after dose increases. Headache, dizziness, and tremor may occur. Despite stimulating effects, bupropion may also cause sedation.

Weight loss is more common with bupropion than weight gain, but both have been reported. Excessive sweating, dry mouth, sore throat, nausea, vomiting, decreased appetite, constipation, blurred vision, and rapid heart rate may occur.

Interactions

Bupropion should not be administered along with other medications that lower the seizure threshold, such as steroids and the asthma medication theophylline. Many psychiatric medications also lower the seizure threshold. Monoamine oxidase inhibitors (MAOs), another type of antidepressant medication, should not be taken with bupropion. Adverse effects may increase in patients taking levodopa and other medications for Parkison's disease along with bupropion. Patients should inform their doctors about all other medications they are taking before starting this drug.

Nicotine patch therapy may be administered concurrently with bupropion in smoking cessation treatment. If this is done, blood pressure must be monitored, since increased blood pressure has been reported with this combination of medications.

Certain drugs, especially those eliminated by the liver, may interfere with the elimination of bupropion from the body, causing higher blood levels and increased side effects. Conversely, bupropion may retard the elimination of other medicines, including many antidepressants, antipsychotic drugs, and heart medications, resulting in higher blood levels and potentially increased side effects.

Resources

BOOKS

American Society of Health-System Pharmacists, Inc. AHFS Drug Information. Edited by Gerald K. McEvoy, Pharm. D. Bethesda, MD: American Society of Health-System Pharmacists, Inc., 2001.

Medical Economics Co. Staff. Physicians' Desk Reference. 55th ed. Montvale, NJ: Medical Economics Company, Inc., 2001.

Nissen, David, ed. Mosby's GenRx 11th ed. St. Louis: Mosby, Inc., 2001.

The United States Pharmacopeia Convention, Inc. USP DI(r) Volume I–. Drug Information for the Health Care Professional. 21st ed. Englewood, CO: Micromedex, Inc., 2001.

The United States Pharmacopeial Convention, Inc. USP DI(r) Volume II–. Advice for the Patient. 21st ed. Englewood, CO: Micromedex, Inc., 2001.

Richard Kapit, M.D.



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