Vilazodone Dosage and Treatment Protocol for Major Depressive Disorder in Adults
The recommended dosage of vilazodone for adults with major depressive disorder is to start with 10 mg once daily with food for 7 days, then increase to 20 mg once daily, with the option to increase to 40 mg once daily after at least 7 days between dosage increases. 1
Initial Dosing and Titration
- Vilazodone must be taken with food to ensure proper absorption 1
- Initial dosage: 10 mg once daily with food for 7 days 1
- After 7 days, increase to 20 mg once daily with food 1
- The dose may be further increased to 40 mg once daily with food after a minimum of 7 days between dosage increases 1
- Target therapeutic dosage range: 20-40 mg once daily 1
Dosage Adjustments for Special Populations
- Patients taking strong CYP3A4 inhibitors: Do not exceed 20 mg once daily (e.g., when taking itraconazole, clarithromycin, voriconazole) 1
- Patients taking strong CYP3A4 inducers: Consider increasing vilazodone dosage by 2-fold, up to a maximum of 80 mg once daily over 1-2 weeks (e.g., when taking carbamazepine, phenytoin, rifampin for >14 days) 1
- Return to original dosage when the interacting medication is discontinued 1
Discontinuation Protocol
Gradual tapering is essential to minimize discontinuation symptoms:
- From 40 mg daily: Reduce to 20 mg daily for 4 days, then to 10 mg daily for 3 days 1
- From 20 mg daily: Reduce to 10 mg daily for 7 days 1
- Abrupt discontinuation should be avoided due to risk of withdrawal symptoms 1
Efficacy and Monitoring
- Significant improvement in depressive symptoms can be observed as early as 1-2 weeks after treatment initiation 2, 3
- Monitor using standardized depression scales such as Montgomery-Åsberg Depression Rating Scale (MADRS) or Hamilton Depression Rating Scale (HAM-D) 2, 3
- Vilazodone has demonstrated efficacy across a broad range of depressive symptoms and severities 3
Safety Considerations
- Prior to initiation: Screen patients for bipolar disorder to avoid triggering manic episodes 1
- Boxed warning: Increased risk of suicidal thoughts and behaviors, particularly in young adults 1
- Drug interactions: Allow at least 14 days between discontinuing MAOIs and starting vilazodone, and vice versa 1
- Common adverse effects: Diarrhea, nausea, vomiting (with 40 mg/day), and insomnia 2
- Vilazodone has limited adverse effects on sexual function and body weight compared to some other antidepressants 4, 5
Clinical Pearls
- Missed doses should be taken as soon as remembered, unless it's almost time for the next dose 1
- Two doses should never be taken at the same time 1
- Long-term treatment (up to 1 year) has shown continued improvement in depressive symptoms 4, 5
- For patients switching from SSRIs or SNRIs to vilazodone, different initiation strategies (10 mg, 20 mg, or 40 mg) have shown similar efficacy, though diarrhea appears more common with direct initiation at 40 mg 6
By following this structured protocol for vilazodone administration in adults with major depressive disorder, clinicians can optimize treatment outcomes while minimizing adverse effects.