Paroxetine (Page 7 of 17)

Clinical Worsening and Suicide Risk:

Patients, their families, and their caregivers should be encouraged to be alert to the emergence of anxiety, agitation, panic attacks, insomnia, irritability, hostility, aggressiveness, impulsivity, akathisia (psychomotor restlessness), hypomania, mania, other unusual changes in behavior, worsening of depression, and suicidal ideation, especially early during antidepressant treatment and when the dose is adjusted up or down. Families and caregivers of patients should be advised to look for the emergence of such symptoms on a day-to-day basis, since changes may be abrupt. Such symptoms should be reported to the patient’s prescriber or health professional, especially if they are severe, abrupt in onset, or were not part of the patient’s presenting symptoms. Symptoms such as these may be associated with an increased risk for suicidal thinking and behavior and indicate a need for very close monitoring and possibly changes in the medication.

Drugs That Interfere with Hemostasis (e.g.,NSAIDs, Aspirin and Warfarin):

Patients should be cautioned about the concomitant use of paroxetine and NSAIDs, aspirin, warfarin, or other drugs that affect coagulation since combined use of psychotropic drugs that interfere with serotonin reuptake and these agents has been associated with an increased risk of bleeding.

Interference with Cognitive and Motor Performance:

Any psychoactive drug may impair judgment, thinking, or motor skills. Although in controlled studies paroxetine tablets have not been shown to impair psychomotor performance, patients should be cautioned about operating hazardous machinery, including automobiles, until they are reasonably certain that therapy with paroxetine tablets does not affect their ability to engage in such activities.

Completing Course of Therapy:

While patients may notice improvement with treatment with paroxetine tablets in 1 to 4 weeks, they should be advised to continue therapy as directed.

Concomitant Medication:

Patients should be advised to inform their physician if they are taking, or plan to take, any prescription or over-the-counter drugs, since there is a potential for interactions.


Although paroxetine tablets have not been shown to increase the impairment of mental and motor skills caused by alcohol, patients should be advised to avoid alcohol while taking paroxetine tablets.


Patients should be advised to notify their physician if they become pregnant or intend to become pregnant during therapy (see WARNINGS — Usage in Pregnancy:Teratogenic Effectsand Nonteratogenic Effects).


Patients should be advised to notify their physician if they are breastfeeding an infant (see PRECAUTIONS — Nursing Mothers).

Laboratory Tests:

There are no specific laboratory tests recommended.

Drug Interactions


As with other serotonin reuptake inhibitors, an interaction between paroxetine and tryptophan may occur when they are coadministered. Adverse experiences, consisting primarily of headache, nausea, sweating, and dizziness, have been reported when tryptophan was administered to patients taking paroxetine tablets. Consequently, concomitant use of paroxetine tablets with tryptophan is not recommended (see WARNINGSSerotonin Syndrome ).

Monoamine Oxidase Inhibitors:



In a controlled study of healthy volunteers, after paroxetine tablets were titrated to 60 mg daily, co-administration of a single dose of 2 mg pimozide was associated with mean increases in pimozide AUC of 151% and Cmax of 62%, compared to pimozide administered alone. The increase in pimozide AUC and Cmax is due to the CYP2D6 inhibitory properties of paroxetine. Due to the narrow therapeutic index of pimozide and its known ability to prolong the QT interval, concomitant use of pimozide and paroxetine tablets is contraindicated (see CONTRAINDICATIONS).

Serotonergic Drugs:

Based on the mechanism of action of SNRIs and SSRIs, including paroxetine hydrochloride, and the potential for serotonin syndrome, caution is advised when paroxetine is coadministered with other drugs that may affect the serotonergic neurotransmitter systems, such as triptans, lithium, fentanyl, tramadol, amphetamines, or St. John’s Wort (see WARNINGSSerotonin Syndrome).

The concomitant use of paroxetine with MAOIs (including linezolid and intravenous methylene blue) is contraindicated (see CONTRAINDICATIONS). The concomitant use of paroxetine with other SSRIs, SNRIs or tryptophan is not recommended (see PRECAUTIONSDrug InteractionsTryptophan).




Preliminary data suggest that there may be a pharmacodynamic interaction (that causes an increased bleeding diathesis in the face of unaltered prothrombin time) between paroxetine and warfarin. Since there is little clinical experience, the concomitant administration of paroxetine tablets and warfarin should be undertaken with caution (see PRECAUTIONS: Drugs That Interfere with Hemostasis).


There have been rare postmarketing reports of serotonin syndrome with the use of an SSRI and a triptan. If concomitant use of paroxetine with a triptan is clinically warranted, careful observation of the patient is advised, particularly during treatment initiation and dose increases (see WARNINGSSerotonin Syndrome).

Drugs Affecting Hepatic Metabolism:

The metabolism and pharmacokinetics of paroxetine may be affected by the induction or inhibition of drug-metabolizing enzymes.


Cimetidine inhibits many cytochrome P450 (oxidative) enzymes. In a study where paroxetine tablets (30 mg once daily) were dosed orally for 4 weeks, steady-state plasma concentrations of paroxetine were increased by approximately 50% during coadministration with oral cimetidine (300 mg three times daily) for the final week. Therefore, when these drugs are administered concurrently, dosage adjustment of paroxetine tablets after the 20-mg starting dose should be guided by clinical effect. The effect of paroxetine on cimetidine’s pharmacokinetics was not studied.


Phenobarbital induces many cytochrome P450 (oxidative) enzymes. When a single oral 30-mg dose of paroxetine tablets was administered at phenobarbital steady state (100 mg once daily for 14 days), paroxetine AUC and T½ were reduced (by an average of 25% and 38%, respectively) compared to paroxetine administered alone. The effect of paroxetine on phenobarbital pharmacokinetics was not studied. Since paroxetine tablets exhibits nonlinear pharmacokinetics, the results of this study may not address the case where the 2 drugs are both being chronically dosed. No initial dosage adjustment of paroxetine tablets is considered necessary when coadministered with phenobarbital; any subsequent adjustment should be guided by clinical effect.

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