Paroxetine Drug Profile

What is Paroxetine?

Paroxetine is a selective serotonin reuptake inhibitor (SSRI) antidepressant medication used to treat depression and various anxiety disorders. It belongs to a class of drugs that work by increasing levels of serotonin, a neurotransmitter in the brain that helps regulate mood, emotions, and behavior. Paroxetine is available in both immediate-release and controlled-release formulations.

Uses

Paroxetine is FDA-approved for several mental health conditions:

• Major depressive disorder: Treatment of episodes of major depression and prevention of relapse
• Generalized anxiety disorder: Management of excessive worry and anxiety that interferes with daily functioning
• Panic disorder: Treatment of panic attacks and prevention of future episodes, with or without agoraphobia
• Social anxiety disorder: Treatment of social phobia and fear of social situations
• Obsessive-compulsive disorder: Reduction of obsessive thoughts and compulsive behaviors
• Post-traumatic stress disorder: Treatment of PTSD symptoms including flashbacks, nightmares, and emotional numbing

How it works

Paroxetine works by blocking the reuptake of serotonin in the brain, which means it prevents nerve cells from reabsorbing this important neurotransmitter after it has been released. This action increases the amount of serotonin available in the spaces between nerve cells, enhancing communication between neurons and helping to improve mood and reduce anxiety. The therapeutic effects typically develop gradually over several weeks of treatment.

Side effects

Common side effects include:

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• Nausea and stomach upset
• Drowsiness or fatigue
• Dry mouth
• Dizziness
• Sexual dysfunction or decreased libido
• Sweating
• Constipation
• Weight gain

Serious side effects requiring immediate medical attention:

• Serotonin syndrome (high fever, agitation, confusion, rapid heartbeat)
• Suicidal thoughts or behaviors, especially in young adults
• Severe allergic reactions with rash, swelling, or difficulty breathing
• Abnormal bleeding or bruising
• Severe withdrawal symptoms if stopped abruptly

Warnings and precautions

• Suicide risk: Paroxetine carries a black box warning for increased risk of suicidal thoughts and behaviors in children, adolescents, and young adults under 25, especially during the first few weeks of treatment
• Pregnancy considerations: Paroxetine is classified as pregnancy category D, meaning it may cause harm to an unborn baby, particularly heart defects when used during the first trimester
• Withdrawal syndrome: Discontinuation should be gradual under medical supervision, as abrupt cessation can cause severe withdrawal symptoms including dizziness, flu-like symptoms, and “brain zaps”
• Liver function: Patients with severe liver impairment may require dosage adjustments as the drug is metabolized in the liver
• Elderly patients: Lower starting doses may be necessary due to increased sensitivity and slower drug clearance

Interactions

Paroxetine has numerous drug interactions due to its effects on liver enzymes:

• MAO inhibitors: Dangerous combination that can cause serotonin syndrome; requires at least 14-day washout period
• Blood thinners (warfarin): Increased bleeding risk due to paroxetine’s effects on platelet function
• Other serotonergic drugs (tramadol, triptans): Risk of serotonin syndrome when combined
• Tamoxifen: Paroxetine may reduce tamoxifen’s effectiveness in breast cancer treatment
• Tricyclic antidepressants: Paroxetine increases blood levels of these drugs, potentially causing toxicity
• Phenytoin: Reduced effectiveness of this seizure medication
• St. John’s Wort: Herbal supplement that increases serotonin syndrome risk
• NSAIDs and aspirin: Increased bleeding risk when used together

Check interactions with the GMJ Interaction Checker

Dosage

Typical adult dosages vary by condition being treated. For depression, the usual starting dose is 20 mg once daily in the morning, which may be increased to 40-50 mg daily if needed. For anxiety disorders, starting doses are often 10-20 mg daily. Panic disorder treatment typically begins at 10 mg daily and may increase to 40 mg daily. Elderly patients usually start with lower doses of 10 mg daily. Dosage adjustments should always be made gradually and under medical supervision. Your healthcare provider will determine the appropriate dose based on your specific condition, response to treatment, and other individual factors.

Sources: FDA DailyMed drug labels (public domain), BNF, WHO Essential Medicines List. This article is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider before starting or stopping any medication.

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