What is the recommended dose of fluvoxamine (selective serotonin reuptake inhibitor)?

Fluvoxamine Dosing Recommendations

Adult Dosing

Start fluvoxamine at 50 mg once daily at bedtime, then increase by 50 mg increments every 4-7 days as tolerated up to a maximum of 300 mg/day, with doses above 100 mg/day split into two divided doses (larger dose at bedtime). 1

Standard Titration Protocol

• Initial dose: 50 mg at bedtime 1
• Titration schedule: Increase by 50 mg every 4-7 days based on tolerability 1
• Therapeutic range: 100-300 mg/day for OCD and anxiety disorders 1
• Dosing frequency: Once daily if ≤100 mg/day; twice daily (unequal split with larger dose at bedtime) if >100 mg/day 1
• Maximum dose: 300 mg/day 1

Special Populations

• Elderly patients: Use lower initial doses and slower titration due to decreased clearance 1
• Hepatic impairment: Modify initial dose and titration schedule due to decreased clearance 1

Pediatric Dosing (Ages 8-17)

Start at 25 mg once daily at bedtime in children and adolescents, then increase by 25 mg increments every 4-7 days, with maximum doses of 200 mg/day for children up to age 11 and 300 mg/day for adolescents. 1

Age-Specific Protocols

• Starting dose: 25 mg at bedtime for all pediatric patients 1
• Titration increments: 25 mg every 4-7 days 1
• Children (ages 8-11): Maximum 200 mg/day due to 2-3 times higher steady-state plasma concentrations compared to adolescents 2, 3
• Adolescents (ages 12-17): Maximum 300 mg/day (similar pharmacokinetics to adults) 2, 3
• Dosing frequency: Twice daily if total dose >50 mg/day, with larger dose at bedtime 1
• Gender consideration: Female children may achieve therapeutic effect at lower doses 1

Clinical Response Timeline

• Initial improvement: Statistically significant improvement may occur within 2 weeks 4
• Clinically meaningful response: Typically by week 6 4
• Maximal benefit: Week 10-12 or later 4
• Trial duration: Continue for at least 10-12 weeks at therapeutic dose before declaring treatment failure 1, 5

Dose-Response Relationship

Higher doses (100-150 mg/day) demonstrate significantly better response rates (73.7%) compared to lower doses (50-75 mg/day, 47.1% response) in depression treatment. 5

• Target therapeutic doses of 100-150 mg/day for optimal efficacy 5
• If no improvement by 6 weeks at adequate dose, consider changing treatment strategy 5

Critical Safety Considerations

Drug Interactions

• Contraindicated with MAOIs: Risk of serotonin syndrome 4
• Extensive CYP450 interactions: Fluvoxamine inhibits CYP1A2, CYP2C19, CYP2C9, CYP3A4, and CYP2D6, creating greater potential for drug-drug interactions compared to other SSRIs 4
• Avoid combining with other serotonergic agents: Including tramadol, dextromethorphan, other SSRIs/SNRIs, and certain opioids 4

Discontinuation Syndrome

• Fluvoxamine carries higher risk: Associated with discontinuation syndrome along with paroxetine and sertraline 4
• Symptoms include: Dizziness, fatigue, myalgias, headaches, nausea, insomnia, sensory disturbances, anxiety, and agitation 4
• Taper gradually: Never discontinue abruptly 1

Common Adverse Effects

• Gastrointestinal: Nausea (most common), abdominal discomfort, diarrhea 2, 3, 6
• CNS effects: Insomnia, sedation, dizziness 2, 3
• Generally mild to moderate severity and often resolve with continued treatment 6

Monitoring Requirements

• Suicidality: Monitor closely during first months and after all dose adjustments, particularly in patients ≤24 years old 4
• Serotonin syndrome: Watch for mental status changes, neuromuscular hyperactivity, autonomic instability, especially within 24-48 hours of dose changes or adding serotonergic agents 4
• Behavioral activation: Monitor for agitation, hypomania, or mania 4

Common Pitfalls to Avoid

• Inadequate dosing: Many patients require 100-300 mg/day for optimal response; 50-75 mg/day is often subtherapeutic 5
• Insufficient trial duration: Must continue for at least 10-12 weeks at therapeutic dose before declaring failure 1, 5
• Forgetting twice-daily dosing: Doses >100 mg/day (adults) or >50 mg/day (pediatrics) require split dosing 1
• Ignoring drug interactions: Fluvoxamine has the most extensive CYP450 interactions among SSRIs 4
• Abrupt discontinuation: High risk of discontinuation syndrome requires gradual taper 4, 1

High-Dose Considerations

• Off-label high doses: Case reports document successful treatment with 600 mg/day in treatment-resistant OCD, though this exceeds FDA-approved maximum 7
• Standard maximum remains 300 mg/day per FDA labeling 1