Serzone® (nefazodone)

BRAND NAME: Serzone®

GENERIC NAME: nefazodone

DRUG CLASS AND MECHANISM: Nefazodone is an antidepressant medication that affects chemicals in the brain that nerves use to send messages to each other, called neurotransmitters. The neurotransmitters that are released by nerves are taken up again by the nerves that release them for reuse. Many experts believe that depression is caused by an imbalance among the amounts of neurotransmitters that are released. Nefazodone works by inhibiting the uptake by nerves of serotonin and norepinephrine, two neurotransmitters, an action which results in more serotonin and norepinephrine to transmit messages to other nerves. Nefazodone is chemically unrelated to the serotonin reuptake inhibitors (SSRIs), the tricyclic antidepressants (TCAs), or the monoamine oxidase (MAO) inhibitors. It is chemically related to another antidepressant, trazodone (Desyrel), and shares its actions. Compared with trazodone, nefazodone has a lesser risk of priapism. (See side effects.)



PREPARATIONS: Tablets (hexagonal): 100, 150, 200, and 250 mg.

STORAGE: Tablets should be kept at room temperature, below 40°C (104°F).

PRESCRIBED FOR: Nefazodone is indicated for the management of depression.

DOSING: Nefazodone is given in two daily doses. As with all antidepressants, the full effect may take a few weeks to become manifest. Doses are often adjusted slowly upward to find the optimal dose. Elderly patients and debilitated persons may need lower doses.

DRUG INTERACTIONS: All antidepressants whose actions include increasing brain concentrations of serotonin, including nefazodone, should not be taken with any of the MAO (mono-amine oxidase) inhibitor- class of antidepressants Such combinations may lead to confusion, high blood pressure, tremor, and increased activity. This same type of interaction may also occur with selegiline (Eldepryl), fenfluramine (Pondimin), and dexfenfluramine (Redux). If a patient is switched from nefazodone to an MAO inhibitor, at least one week should be allowed after stopping the nefazodone.

Nefazodone should not be taken with terfenadine (Seldane) or astemizole (Hismanal) since blood concentrations of these two antihistamines can increase, and increases can cause potentially life-threatening abnormal heart rhythms. Nefazodone can markedly increase the blood concentrations of triazolam (Halcion) and alprazolam (Xanax), resulting in excessive sedation and impaired ability to perform tasks. It is recommended that people taking triazolam who need to be started on nefazodone should have their triazolam dose reduced by 75%. Similarly, those people taking alprazolam who need to start taking nefazodone should have their alprazolam dose reduced by 50%. Nefazodone may increase the blood concentration of digoxin (Lanoxin), possibly leading to digoxin toxicity with side effects such as altered vision or nausea.

PREGNANCY: There are no adequate studies of nefazodone in pregnant women. Studies in animals have not demonstrated any adverse effects on the developing fetus, but some studies in animals found that the animal offspring were of low weight and died more frequently than those whose mothers were not exposed to the drug. Nefazodone can be used in pregnancy only if the physician feels that its benefits outweigh its potential risks.

NURSING MOTHERS: It is not known if nefazodone is secreted in breast milk.

SIDE EFFECTS: The most commonly noted side effects associated with nefazodone are nausea, dizziness, insomnia, agitation, tiredness, dry mouth, constipation, lightheadedness, blurred vision, and confusion. Rarely, nefazodone is associated with priapism or prolonged penile erection. Although the erection usually subsides eventually, occasionally blood clots form within the penis and cause serious damage to the penis.

“If antidepressants are discontinued abruptly, symptoms may occur such as dizziness, headache, nausea, changes in mood, or changes in the sense of smell, taste, etc. (Such symptoms even may occur when even a few doses of antidepressant are missed.) Therefore, it is recommended that the dose of antidepressant be reduced gradually when therapy is discontinued.”

Last Editorial Review: 12/31/1997

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