What is the recommended dosing for fluoxetine (fluoxamine)?

Fluvoxamine Dosing Recommendations

The recommended starting dose for fluvoxamine in adults is 50 mg administered as a single daily dose at bedtime, with gradual increases in 50 mg increments every 4-7 days as tolerated, up to a maximum of 300 mg daily. 1

Adult Dosing Protocol

Initial Dosing

• Start with 50 mg once daily at bedtime 1
• Increase dose in 50 mg increments every 4-7 days as tolerated 1
• Target dose range: 100-300 mg/day 1
• For doses above 100 mg/day, divide into two doses with the larger dose at bedtime 1

Special Populations

• Elderly patients: Start with lower doses due to decreased clearance 1
• Hepatically impaired patients: Start with lower doses and titrate more slowly 1
• Pregnant women (third trimester): Consider tapering dose due to risk of complications in newborns 1

Pediatric Dosing Protocol

Children (8-11 years)

• Start with 25 mg once daily at bedtime 1
• Increase in 25 mg increments every 4-7 days as tolerated 1
• Maximum dose: 200 mg/day 1
• For doses above 50 mg/day, divide into two doses 1

Adolescents (12-17 years)

• Start with 25 mg once daily at bedtime 1
• Increase in 25 mg increments every 4-7 days as tolerated 1
• Maximum dose: up to 300 mg/day (adult maximum) 1
• For doses above 50 mg/day, divide into two doses 1

Efficacy Considerations

Research indicates that higher daily doses (100-150 mg) of fluvoxamine show better response rates (73.7%) compared to lower daily doses (50-75 mg) with response rates of 47.1% 2. A 6-week trial period is generally sufficient to determine efficacy, with over 80% of responders showing improvement by the end of this period 2.

Drug Interactions

Fluvoxamine is a potent inhibitor of CYP1A2, moderate inhibitor of CYP2C19 and CYP3A4, and a weak inhibitor of CYP2D6 3. Even at low doses (10-20 mg daily), fluvoxamine can significantly inhibit the metabolism of drugs metabolized by CYP1A2 and CYP2C19 4.

Important precaution: Allow at least 14 days between discontinuation of an MAOI and initiation of fluvoxamine, and vice versa 1.

Treatment Duration

For obsessive-compulsive disorder, which is a primary indication for fluvoxamine, several months or longer of sustained pharmacologic therapy is generally required 1. Maintenance therapy with fluvoxamine may reduce the likelihood of relapses in up to 67% of patients with OCD 3.

Common Side Effects

Most common adverse events include:

• Nausea (>10% of patients) 3
• Less common: somnolence, asthenia, headache, dry mouth, and insomnia 3

Fluvoxamine has a low risk of suicidal behavior, sexual dysfunction, and withdrawal syndrome compared to other antidepressants 3.

Clinical Pearls

• If a patient does not show improvement by the end of 6 weeks, consider altering the treatment regimen 2
• Fluvoxamine has fewer anticholinergic and cardiovascular side effects compared to tricyclic antidepressants 3
• Taking the medication at bedtime may help minimize daytime sedation
• For anxiety disorders, fluvoxamine is recommended as a first-line treatment option 3