paroxetine (Paxil, Pexeva)

Paroxetine is an oral drug that is used for treating depression. It is in a class of drugs called selective serotonin reuptake inhibitors (SSRIs), a class that also contains fluoxetine (Prozac), citalopram (Celexa), and sertraline (Zoloft). Paroxetine affects neurotransmitters, the chemicals that nerves within the brain use to communicate with each other. Neurotransmitters are manufactured and released by nerves and then travel and attach to nearby nerves. Thus, neurotransmitters can be thought of as the communication system of the brain. Serotonin is one neurotransmitter that is released by nerves in the brain. The serotonin either travels across the space that lies between nerves and attaches to receptors on the surface of nearby nerves or it attaches to receptors on the surface of the nerve that produced it, to be taken up by the nerve and released again (a process referred to as re-uptake).

Many experts believe that an imbalance among neurotransmitters is the cause of depression. Paroxetine works by preventing the reuptake of one neurotransmitter, serotonin, by nerve cells after it has been released. Since reuptake is an important mechanism for removing released neurotransmitters and terminating their actions on adjacent nerves, the reduced uptake caused by paroxetine increases free serotonin that stimulates nerve cells in the brain. The FDA approved paroxetine in December 1992.

Paxil, Paxil CR, Pexeva

GENERIC AVAILABLE: Yes

Yes

Common side effects of paroxetine are:

• nausea,
• headaches,
• anxiety,
• insomnia,
• drowsiness,
• constipation,
• weakness,
• dry mouth,
• sweating,
• diarrhea and
• loss of appetite.

Other important side effects include:

• increased blood pressure
• seizures
• sexual dysfunction

Some patients may experience withdrawal reactions upon stopping paroxetine. Symptoms of withdrawal include:

• anxiety,
• nausea,
• nervousness, and
• insomnia.

The dose of paroxetine should be gradually reduced when therapy is discontinued.

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 paroxetine 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.

The recommended dose is 20-60 mg daily of immediate release tablets or 12.5-75 mg daily using controlled release tablets. Paroxetine is given as a single daily dose, usually in the morning. As with all anti-depressants, the full effect may not occur until after a few weeks of therapy.

Doses for obsessive-compulsive disorders and panic disorders are often higher than those for depression. Doses often are adjusted to find the optimal dose.

Elderly patients, debilitated persons, and patients with certain kidney or liver diseases may need lower doses because they metabolize and eliminate paroxetine more slowly and, therefore, are prone to develop high blood levels and toxicity.

All SSRIs, including paroxetine, should not be taken with any of the monoamine oxidase inhibitor (MAOI) class of antidepressants, for example, isocarboxazid (Marplan), phenelzine (Nardil), tranylcypromine (Parnate), selegiline (Eldepryl, Carbex), and procarbazine (Matulane) or other drugs that inhibit monoamine oxidase such as linezolid (Zyvox) and intravenous methylene blue.

Such combinations may lead to confusion, high blood pressure, tremor, hyperactivity, coma, and death. (A period of 14 days without treatment should lapse when switching between paroxetine and MAOIs.) Similar reactions occur when paroxetine is combined with other drugs for example, tryptophan, St. John's wort, meperidine (Demerol), tramadol (Ultram) that increase serotonin in the brain.

Paroxetine may increase the effect of the blood thinner, warfarin (Coumadin), leading to excessive bleeding. Therefore, warfarin therapy should be monitored more frequently in patients who are also taking paroxetine. Combining SSRIs such as paroxetine with aspirin, nonsteroidal anti-inflammatory drugs or other drugs that affect bleeding may increase the likelihood of upper gastrointestinal bleeding. Phenytoin (Dilantin) and phenobarbital may decrease the amount of paroxetine in the body and possibly reduce its effectiveness.

Use of paroxetine during pregnancy may result in congenital heart defects. Paroxetine should not be administered to pregnant women unless the need justifies the risk.

Paroxetine is secreted in breast milk. Mothers who are taking paroxetine should consider not breastfeeding.

What preparations of paroxetine are available?

Tablets: 10, 20, 30, and 40 mg; Paxil CR Tablets: 12.5, 25, and 37.5 mg; Suspension: 10 mg/5ml

How should I keep paroxetine stored?

Tablets should be kept at room temperature, 59 F - 86 F (15 C - 30 C). The suspension and controlled release tablets should be stored at or below 77 F (25 C).