What is the starting dose of Paxil (paroxetine)?

Starting Dose of Paroxetine (Paxil)

The recommended starting dose of paroxetine (Paxil) is 20 mg once daily, typically administered in the morning with or without food. 1

Dosing Guidelines by Indication

Major Depressive Disorder

• Initial dose: 20 mg once daily
• Dose adjustments: May increase by 10 mg/day increments at intervals of at least 1 week
• Maximum dose: 50 mg/day
• Effective dose range in clinical trials: 20-50 mg/day

Anxiety Disorders

• Panic Disorder:

  • Initial dose: 10 mg once daily
  • Target dose: 40 mg/day
  • Maximum dose: 60 mg/day

• Obsessive-Compulsive Disorder (OCD):

  • Initial dose: 20 mg once daily
  • Target dose: 40 mg/day
  • Maximum dose: 60 mg/day

• Social Anxiety Disorder:

  • Initial dose: 20 mg once daily
  • Effective dose range: 20-60 mg/day, though evidence suggests no additional benefit above 20 mg/day 1

• Generalized Anxiety Disorder:

  • Initial dose: 20 mg once daily
  • Maximum dose: 50 mg/day, though evidence suggests no additional benefit above 20 mg/day 1

• Post-Traumatic Stress Disorder:

  • Initial dose: 20 mg once daily
  • Dose range: 20-50 mg/day 1

Special Populations

Elderly Patients

• Starting dose should be lower (approximately 50% of the adult starting dose) 2
• Therapeutic dose range: 20-40 mg/day 3
• Paroxetine is generally well tolerated in elderly individuals 4

Patients with Hepatic or Renal Impairment

• Consider dose adjustments for patients with hepatic impairment 2
• Consider dose adjustments for patients with renal impairment 2

Administration Guidelines

• Administer as a single daily dose, usually in the morning
• Can be taken with or without food
• Dose changes should occur at intervals of at least 1 week
• For most patients, 20 mg/day will be the optimal dose 3
• If inadequate response after 1-3 weeks, increase dose in 10-mg increments at weekly intervals 3

Important Clinical Considerations

• Paroxetine has the highest potency for serotonin reuptake inhibition among SSRIs 5
• Unlike some other SSRIs, paroxetine has weak affinity for muscarinic cholinergic receptors, which may contribute to certain side effects 5
• Steady-state levels are achieved after 4-14 days of treatment 5
• The elimination half-life of approximately 21 hours is consistent with once-daily dosing 5

Common Pitfalls to Avoid

• Avoid abrupt discontinuation to prevent withdrawal syndrome
• Avoid concurrent use with MAOIs due to risk of serotonin syndrome
• Be aware of potential drug interactions as paroxetine is both a substrate and inhibitor of cytochrome P450 2D6 enzyme 5
• Monitor for common side effects including nausea, sexual dysfunction, somnolence, headache, and dry mouth 4

Paroxetine is generally well tolerated with a safety profile similar to other SSRIs, making it an appropriate first-line treatment option for major depressive disorder and various anxiety disorders 4.