What is the recommended dosage of Fluvoxamine for obsessive-compulsive disorder (OCD)?

Fluvoxamine Dosing for Obsessive-Compulsive Disorder

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

Adult Dosing Algorithm

Initial Dosing:

• Begin with 50 mg as a single dose at bedtime 1
• This starting dose applies to most adults, though elderly or hepatically impaired patients may require lower initial doses due to decreased clearance 1

Titration Schedule:

• Increase by 50 mg increments every 4-7 days based on tolerability 1
• The therapeutic range established in controlled trials is 100-300 mg/day 2, 1
• Maximum dose: 300 mg/day 1

Dose Division:

• Total daily doses ≤100 mg: give as single bedtime dose 1
• Total daily doses >100 mg: split into two divided doses, with the larger portion given at bedtime 1

Treatment Duration:

• Allow at least 8-12 weeks at maximum tolerated dose before declaring treatment failure 3
• Although efficacy beyond 10 weeks has not been documented in controlled trials, OCD is chronic and continuation is reasonable for responders 1
• Maintain treatment for 12-24 months after achieving remission due to high relapse rates 3

Pediatric Dosing (Ages 8-17)

Starting Dose:

• 25 mg once daily at bedtime 1

Titration:

• Increase by 25 mg increments every 4-7 days as tolerated 1
• Children up to age 11: maximum 200 mg/day 1
• Adolescents: may titrate up to adult maximum of 300 mg/day 1
• Female children may achieve therapeutic effect at lower doses 1

Dose Division:

• Doses >50 mg/day should be split into two divided doses, with larger dose at bedtime 1

Critical Drug Interactions

Fluvoxamine is a potent CYP1A2 inhibitor and moderate inhibitor of CYP2C19 and CYP3A4, requiring careful attention to drug interactions. 4, 2

• Avoid concomitant use with alprazolam or triazolam due to significant interaction risk 4, 2
• Reduce alprazolam or triazolam dose by 50% if co-administration is unavoidable 4
• Monitor for interactions with other medications metabolized by these pathways 2

Discontinuation

Taper gradually rather than stopping abruptly to minimize discontinuation syndrome. 1

• Fluvoxamine has a shorter half-life compared to some other SSRIs, increasing risk of discontinuation symptoms 2
• Monitor patients for withdrawal symptoms during dose reduction 1
• In pregnant women during third trimester, carefully weigh risks/benefits and consider tapering to avoid neonatal complications 1

Special Populations

Elderly and Hepatically Impaired:

• Use lower initial doses and slower titration due to decreased clearance 1
• These patients are more prone to adverse effects at standard doses 1

Common Pitfalls to Avoid

• Inadequate dose or duration: Many patients require doses in the 200-300 mg/day range and full 8-12 weeks for response 2, 3
• Premature discontinuation: Stopping too early increases relapse risk 3
• Missing drug interactions: Always check for CYP1A2, CYP2C19, and CYP3A4 substrates before prescribing 2
• Single daily dosing at higher doses: Doses >100 mg/day should be split to improve tolerability 1

Tolerability Profile

Fluvoxamine is generally well tolerated, with nausea being the most common adverse event (>10% of patients), followed by somnolence, asthenia, headache, dry mouth, and insomnia 5. The drug has fewer anticholinergic and cardiovascular effects compared to tricyclic antidepressants like clomipramine, with superior tolerability despite similar efficacy 6.