Paroxetine

7 DRUG INTERACTIONS Table 9 presents clinically significant drug interactions with paroxetine. Table 9 Clinically Significant Drug Interactions with Paroxetine Monoamine Oxidase Inhibitors (MAOIs) Clinical Impact The concomitant use of SSRIs, including paroxetine, and MAOIs increases the risk of serotonin syndrome. Intervention Paroxetine is contraindicated in patients taking MAOIs, including MAOIs such as linezolid or intravenous methylene blue [see Dosage and Administration ( 2.5 ), Contraindications ( 4 ), Warnings and Precautions ( 5.2 )] . Examples selegiline, tranylcypromine, isocarboxazid, phenelzine, linezolid, methylene blue Pimozide and Thioridazine Clinical Impact Increased plasma concentrations of pimozide and thioridazine, drugs with a narrow therapeutic index, may increase the risk of QTc prolongation and ventricular arrhythmias. Intervention Paroxetine is contraindicated in patients taking pimozide or thioridazine [see Contraindications ( 4 )] . Other Serotonergic Drugs Clinical Impact The concomitant use of serotonergic drugs with paroxetine increases the risk of serotonin syndrome. Intervention Monitor patients for signs and symptoms of serotonin syndrome, particularly during treatment initiation and dosage increases. If serotonin syndrome occurs, consider discontinuation of paroxetine and/or concomitant serotonergic drugs [see Warnings and Precautions ( 5.2 )] . Examples other SSRIs, SNRIs, triptans, tricyclic antidepressants, opioids, lithium, tryptophan, buspirone, amphetamines and St. John's Wort. Drugs that Interfere with Hemostasis (antiplatelet agents and anticoagulants) Clinical Impact The concurrent use of an antiplatelet agent or anticoagulant with paroxetine may potentiate the risk of bleeding. Intervention Inform patients of the increased risk of bleeding associated with the concomitant use of paroxetine and antiplatelet agents and anticoagulants. For patients taking warfarin, carefully monitor the international normalized ratio [see Warnings and Precautions ( 5.5 )] . Examples aspirin, clopidogrel, heparin, warfarin Drugs Highly Bound to Plasma Protein Clinical Impact Paroxetine is highly bound to plasma protein. The concomitant use of paroxetine with another drug that is highly bound to plasma protein may increase free concentrations of paroxetine or other tightly-bound drugs in plasma. Intervention Monitor for adverse reactions and reduce dosage of paroxetine or other protein-bound drugs as warranted. Examples warfarin Drugs Metabolized by CYP2D6 Clinical Impact Paroxetine is a CYP2D6 inhibitor [see Clinical Pharmacology ( 12.3 )] . The concomitant use of paroxetine with a CYP2D6 substrate may increase the exposure of the CYP2D6 substrate. Intervention Decrease the dosage of a CYP2D6 substrate if needed with concomitant paroxetine use. Conversely, an increase in dosage of a CYP2D6 substrate may be needed if paroxetine is discontinued. Examples propafenone, flecainide, atomoxetine, desipramine, dextromethorphan, metoprolol, nebivolol, perphenazine, tolterodine, venlafaxine, risperidone. Tamoxifen Clinical Impact Concomitant use of tamoxifen with paroxetine may lead to reduced plasma concentrations of the active metabolite (endoxifen) and reduced efficacy of tamoxifen Intervention Consider use of an alternative antidepressant with little or no CYP2D6 inhibition [see Warnings and Precautions ( 5.11 )] . Fosamprenavir/Ritonavir Clinical Impact Co-administration of fosamprenavir/ritonavir with paroxetine significantly decreased plasma levels of paroxetine. Intervention Any dose adjustment should be guided by clinical effect (tolerability and efficacy). • Drugs Highly Bound to Plasma Protein: Monitor for adverse reactions and reduce dosage of paroxetine or other protein-bound drugs (e.g., warfarin) as warranted. ( 7 ) • Drugs Metabolized by CYP2D6: Reduce dosage of drugs metabolized by CYP2D6 as warranted. ( 7 ) • Concomitant use with tamoxifen: Consider use of an alternative antidepressant with little or no CYP2D6 inhibition. ( 5.11 , 7 )

Paroxetine tablets are indicated in adults for: - Major depressive disorder (MDD) - Obsessive compulsive disorder (OCD) - Panic disorder (PD) - Social anxiety disorder (SAD) - Generalized anxiety disorder (GAD) - Posttraumatic stress disorder (PTSD). The label states "paroxetine tablets, USP is not approved for use in pediatric patients."

2 DOSAGE AND ADMINISTRATION • Recommended starting and maximum daily dosage for MDD, OCD, PD, and PTSD: ( 2.2 ) Indication Starting Daily Dose Maximum Daily Dose MDD 20 mg 50 mg OCD 20 mg 60 mg PD 10 mg 60 mg PTSD 20 mg 50 mg • Recommended starting dosage for SAD and GAD is 20 mg daily. ( 2.3 ) • Elderly patients, patients with severe renal impairment or severe hepatic impairment: Starting dosage is 10 mg daily. Maximum dosage is 40 mg daily. ( 2.4 ) • When discontinuing paroxetine tablets, reduce dosage gradually. ( 2.6 , 5.7 ) 2.1 Administration Information Administer paroxetine tablets as a single daily dose in the morning, with or without food. 2.2 Recommended Dosage for MDD, OCD, PD, and PTSD The recommended starting dosages and maximum dosages of paroxetine tablets in patients with MDD, OCD, PD, and PTSD are presented in Table 1. In patients with an inadequate response, increase dosage in increments of 10 mg per day at intervals of at least 1 week, depending on tolerability. Table 1 Recommended Daily Dosage of Paroxetine Tablets in Patients with MDD, OCD, PD, and PTSD Indication Starting Dose Maximum Dose MDD 20 mg 50 mg OCD 20 mg 60 mg PD 10 mg 60 mg PTSD 20 mg 50 mg 2.3 Recommended Dosage for SAD and GAD SAD The starting and recommended dosage in patients with SAD is 20 mg daily. In clinical trials the effectiveness of paroxetine tablets was demonstrated in patients dosed in a range of 20 mg to 60 mg daily. While the safety of paroxetine tablets has been evaluated in patients with SAD at doses up to 60 mg daily, available information does not suggest any additional benefit for doses above 20 mg daily [see Clinical Studies ( 14.4 )]. GAD The starting and recommended dosage in patients with GAD is 20 mg daily. In clinical trials the effectiveness of paroxetine tablets in GAD was demonstrated in patients dosed in a range of 20 mg to 50 mg daily. There is not sufficient evidence to suggest a greater benefit to doses higher than 20 mg daily [see Clinical Studies ( 14.5 )]. In patients with an inadequate response, increase dosage in increments of 10 mg per day at intervals of at least 1 week, depending on tolerability. 2.4 Screen for Bipolar Disorder Prior to Starting Paroxetine Tablets Prior to initiating treatment with paroxetine tablets or another antidepressant, screen patients for a personal or family history of bipolar disorder, mania, or hypomania [see Warnings and Precautions ( 5.6 )]. 2.5 Recommended Dosage for Elderly Patients, Patients with Severe Renal Impairment, and Patients with Severe Hepatic Impairment The recommended initial dosage is 10 mg per day for elderly patients, patients with severe renal impairment, and patients with severe hepatic impairment. Dosage should not exceed 40 mg/day. 2.6 Switching Patients to or From a Monoamine Oxidase Inhibitor (MAOI) At least 14 days must elapse between discontinuation of a monoamine oxidase inhibitor (MAOI and initiation of paroxetine tablets. In addition, at least 14 days must elapse after stopping paroxetine before starting an MAOI antidepressant [see Contraindications ( 4 ), Warnings and Precautions ( 5.2 )]. 2.7 Discontinuation of Treatment With Paroxetine Tablets Adverse reactions may occur upon discontinuation of paroxetine tablets [see Warnings and Precautions ( 5.7 )]. Gradually reduce the dosage rather than stopping paroxetine abruptly whenever possible.

The most common reactions (occurring in ≥5% of patients and at roughly twice the placebo rate) include "abnormal ejaculation, asthenia, constipation, decreased appetite, diarrhea, dizziness, dry mouth, female genital disorder, impotence, infection, insomnia, libido decreased, nausea, nervousness, somnolence, sweating, tremor, yawn." Sexual dysfunction is common, with men reporting "ejaculatory delay or failure, decreased libido, and erectile dysfunction" and women reporting decreased libido and delayed or absent orgasm. Rare but serious postmarketing events include Stevens-Johnson syndrome, toxic epidermal necrolysis, acute pancreatitis, and severe hepatic injury.