paroxetine

Paroxetine is a selective serotonin reuptake inhibitor (SSRI) used as an antidepressant and to treat various anxiety and mood disorders. In addition to major depressive disorder, it is prescribed for generalized anxiety disorder, social anxiety disorder, panic disorder, obsessive-compulsive disorder, post-traumatic stress disorder, premenstrual dysphoric disorder, and, in certain formulations, vasomotor symptoms associated with menopause (Brisdelle). It is commonly sold under brand names such as Paxil, Paxil CR, and Pexeva.

Paroxetine works by blocking the reabsorption of serotonin in the brain, increasing its availability in the synaptic cleft. It is administered orally and is extensively metabolized in the liver, with a typical half-life of about 21 to 24 hours, though the exact duration can vary among individuals. It has notable interactions with the cytochrome P450 system, particularly CYP2D6, and is a potent inhibitor of this enzyme, which can affect the metabolism of other drugs, including tamoxifen.

Common and important adverse effects include nausea, dry mouth, sleep disturbances, sexual dysfunction, weight changes, sweating, and dizziness. Paroxetine can cause sedation or agitation in some people and carries a risk of hyponatremia in older adults. It has a relatively high incidence of discontinuation or withdrawal symptoms if stopped abruptly, so gradual tapering is recommended. There is an increased risk of suicidal thoughts in younger patients, especially early in treatment or when adjusting doses. Serotonergic agents in combination raise the risk of serotonin syndrome.

In pregnancy, paroxetine is generally avoided when possible due to potential fetal risks, including congenital heart defects. As with all medications, use during pregnancy and lactation should involve careful discussion of benefits and risks.