Paroxetine

Antidepressant Drug

Drug class: Selective Serotonin Reuptake Inhibitor

Paroxetine (SEROXAT)（中文：帕羅西汀）

Common Strengths of Paroxetine

Paroxetine are available in the following strengths:

• 10 mg, 20 mg, 30 mg, 40 mg tablets
• 12.5 mg, 25 mg, 37.5 mg, controlled-release tablets
• 10 mg/5 mL oral suspension
• 10 mg/mL oral drops

Drug Trade Names of Paroxetine

SEROXAT

Drug Usage

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

Mechanism of Action

Paroxetine is a selective serotonin reuptake inhibitor (SSRI). It works by increasing serotonin levels in the brain by inhibiting its reuptake into presynaptic neurons, thereby enhancing serotonergic acitivity.

Route of Administration

Oral

Dosages

• Depression: 20 mg/day initially, may increase to 50 mg/day maximum
• Obsessive-compulsive disoreder (OCD): 20 mg/day initially, may increase to 60 mg/ day maximum
• Panic disorder: 10 mg/day initially, may increase to 60 mg/day maximum
• Social anxiety disorder, generalized anxiety disorder, Post-traumatic stress disorder (PTSD): 20 mg/day initially, may increase to 50 mg/day maximum

Renal dose based on eGFR:

• For severe renal impairment (eGFR ≥ 30 mL/min):
  • Immediate-release tablets: 10 mg/day initially, may titrate up to 40 mg/day maximum
  • Controlled-release tablets: 12.5 mg/day initially, may titrate up to 50 mg/day maximum

Side Effects

Frequency	Adverse reactions
Common	These side effects are generally mild and often subside as the body adjusts to the medication.
	Nausea: Often mitigated by taking the medication with food
	Headaches: Drinking plenty of fluids and resting can help; avoid excessive alcohol consumption
	Insomnia: Taking fluoxetine in the morning may reduce sleep disturbances
	Fatigue or Weakness: Resting and avoiding activities that require alertness, such as driving
	Sexual Dysfunction: This includes decreased libido and difficulty achieving orgasm
	Constipation or diarrhea
	Dry Mouth: Using sugar-free gum or candy can help alleviate dry mouth
	Dizziness: Moving slowly when changing positions can help reduce dizziness
	Sweating
	Anxiety
	Tremor/shaking
Serious	Serious side effect are less common but require immediate medical attention.
	Suicidal Thoughts or Actions: especially in the first few months of treatment or when the dose is changed. Symptoms include new or worsening depression, anxiety, or unusual changes in mood or behavior.
	Serotonin Syndrome: This potentially life-threatening condition can occur when there is too much serotonin in the body. Symptoms include agitation, hallucinations, rapid heart rate, fever, nausea, vomiting, diarrhea, and muscle twitching.
	Severe Allergic Reactons: These include symptoms like difficulty breathing, swelling of the face, lips, tongue, or throat, and severe rash or hives.
	Abnormal Bleeding: Can manifest as unusual bruising or bleeding.
	Low Sodium Levels: Particularly in older adults, symptoms include headache, confusion, weakness, and difficulty concentrating.
	Mania: Symptoms include excessively high energy, severe trouble sleeping, racing thoughts, reckless behavior, and unusually grand ideas
	Seizures
	Angle-closure glaucoma (eye pain, vision changes)
	Bone fractures (increased riks)
	QT interval prolongation may lead to heart arrhythmias
	Discontinuation syndrome if stopped abruptly

Pharmacokinetics

• Metabolism: Hepatic via mainly CYP2D6 and CYP3A4
• Elimination: Primarily renal
• Half-life: approximately 21 hours
• Onset: 4 - 6 weeks for full antidepressant effect

Drug Precautions

Pregnancy

Use only if the potential benefit justifies the risk to the fetus

Breastfeeding

Present in breast milk

Children and Elderly

Not approved for use in pediatric patients. Lower doses are recommended for elderly due to increased sensitivity to side effects

Monitoring Requirements

• Monitor for suicidal thoughts, especially in young adults
• Monitor for serotonin syndrome, especially when combined with other serotonergic drugs
• Regularly assess liver function and electrolyte levels
• Suicidal thoughts, serotonin syndrome, liver function, electrolyte levels

Drug Interactions

• Contraindicated with thioridazine due to risk of serotonin syndrome and QT prolongation
• Caution with other serotonergic drugs, NSAIDs, anticoagulants, and drugs affecting CYP2D6 metabolism

FAQ

How Should I Take the Tablet?

Take orally with or without food, usually once daily in the morning.

What Should I Avoid While Taking?

Avoid alcohol and activities requiring mental alertness until you know how the tablet affects you.

What Happens if I Miss a Dose?

Take the missed dose as soon as you remember unless it is almost time for your next dose. Do not double doses.