Generic Name

Paroxetine Mesylate

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Classification

FDA Approved Indications

• Major depressive disorder
• Obsessive-compulsive disorder (OCD)
• Panic disorder
• Social anxiety disorder
• Post-traumatic stress disorder (PTSD)
• Premenstrual dysphoric disorder (Brisdelle)
• Generalized anxiety disorder

Mechanism of Action

Paroxetine selectively inhibits the reuptake of serotonin in the central nervous system, increasing serotonin activity in synaptic clefts, which helps to alleviate symptoms of depression and anxiety.

Dosage and Administration

Adult: Dose varies by condition; typical starting dose for depression is 20 mg daily, adjustable based on response. Max dose up to 50 mg daily.

Pediatric: Not approved for pediatric use for depression; for OCD in children ≥6 years, starting at 10 mg daily, max 60 mg.

Geriatric: Start at lower doses due to increased sensitivity; monitor closely.

Renal Impairment: Use with caution; dose adjustments may be necessary.

Hepatic Impairment: Use with caution; start at lower dose and titrate carefully.

Pharmacokinetics

Absorption: Well absorbed orally, with peak plasma concentrations in about 5 hours.

Distribution: Widely distributed; protein binding approximately 95%.

Metabolism: Extensively metabolized in the liver primarily via CYP2D6.

Excretion: Metabolites excreted in urine; small amount excreted unchanged in urine.

Half Life: Approximately 21 hours, allowing for once-daily dosing.

Contraindications

• Concurrent use with monoamine oxidase inhibitors (MAOIs)
• Hypersensitivity to paroxetine

Precautions

• Risk of serotonin syndrome, especially when combined with other serotonergic agents
• Suicidality risk, especially in adolescents and young adults
• Use cautiously in patients with bleeding disorders or on anticoagulants
• Do not abruptly discontinue to avoid withdrawal symptoms

Adverse Reactions - Common

• Nausea (Frequent)
• Insomnia (Frequent)
• Somnolence (Frequent)
• Dry mouth (Frequent)
• Dizziness (Frequent)

Adverse Reactions - Serious

• Serotonin syndrome (Rare)
• QT interval prolongation (Rare)
• Suicidal ideation (Less common in adults)
• Hyponatremia (Less common)

Drug-Drug Interactions

• Use with other serotonergic drugs (e.g., triptans, MAOIs, tramadol) increases serotonin syndrome risk.
• Caution with anticoagulants and antiplatelet agents due to bleeding risk.

Drug-Food Interactions

• Alcohol may increase sedative effects and risk of bleeding.

Drug-Herb Interactions

• St. John’s Wort and other serotonergic herbs may increase serotonin syndrome risk.

Nursing Implications

Patient/Family Teaching

• Take medication exactly as prescribed.
• Report signs of serotonin syndrome (confusion, hallucination, seizure, severe dizziness, vaping or fever).
• Avoid alcohol and illicit drugs.
• Do not stop medication abruptly.
• Follow-up appointments are necessary for dose adjustments.

Special Considerations

Black Box Warnings:

• Increased risk of suicidal thoughts and behaviors in children, adolescents, and young adults under 25.
• Risk of serotonin syndrome, especially with concomitant serotonergic agents.

Genetic Factors: Genetic variations in CYP2D6 can affect metabolism.

Lab Test Interference: May cause falsely elevated blood glucose levels in some assays.

Overdose Management

Signs/Symptoms: Nausea, vomiting, dizziness, tremor, sweating, seizures, serotonin syndrome symptoms.

Treatment: Supportive care, activated charcoal if recent ingestion, monitoring vital signs, benzodiazepines for agitation or seizures, serotonin syndrome management with rapid discontinuation of serotonergic agents and supportive care.

Storage and Handling

Storage: Store at room temperature, 20-25°C (68-77°F).

Stability: Stable when stored properly in a dry place.