BLACK BOX WARNING
- suicidality in children, adolescents, and young adults
vilazodone
Brand: Viibryd
⚠ BBW Prototype Drug
Drug Class: SPARI (serotonin partial agonist reuptake inhibitor)
Drug Family: antidepressant
Subclass: novel antidepressant
Organ Systems: cns
Mechanism of Action
Combines SSRI activity (SERT blockade) with 5-HT1A partial agonism, similar to buspirone. The partial agonism at 5-HT1A autoreceptors may accelerate the desensitization that underlies antidepressant onset, and 5-HT1A postsynaptic partial agonism may contribute to anxiolytic effects.
SERT (serotonin transporter)5-HT1A receptor (partial agonist)
Indications
- major depressive disorder
Contraindications
- concurrent MAOI use
Adverse Effects
Common
- diarrhea
- nausea
- vomiting
- insomnia
- dry mouth
Serious
- serotonin syndrome
- suicidal ideation
- abnormal bleeding
- hyponatremia
Pharmacokinetics (ADME)
| Absorption | bioavailability ~72% with food (must take with food); food increases Cmax by ~147-160% |
| Distribution | protein binding ~96-99% |
| Metabolism | primarily via CYP3A4 (major) with minor CYP2C19 and CYP2D6 contribution |
| Excretion | fecal (~2% unchanged); renal (~1% unchanged) |
| Half-life | 25 hours |
| Onset | 2-4 weeks for antidepressant effect |
| Peak | 4-5 hours |
| Duration | 24 hours |
| Protein Binding | 96-99% |
| Vd | approximately 1400 L |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| MAOIs | serotonin syndrome | contraindicated |
| strong CYP3A4 inhibitors | increases vilazodone exposure by 50%; reduce dose to 20 mg/day | major |
| strong CYP3A4 inducers | decreases vilazodone levels; increase dose to 80 mg/day | moderate |
Nursing Considerations
- Vilazodone must be taken with food; administration on an empty stomach reduces bioavailability by 50% and may reduce efficacy.
- Dose titration is required: start at 10 mg for 7 days, then 20 mg for 7 days, then target 40 mg daily; this gradual titration minimizes GI side effects.
- Diarrhea is the most common adverse effect (28% in trials), occurring predominantly in the first 2 weeks; reassure patients this often resolves.
- Unlike SSRIs, sexual dysfunction appears less prevalent with vilazodone, possibly due to 5-HT1A agonism counteracting 5-HT2A-mediated sexual effects.
Clinical Pearls
- Vilazodone's dual mechanism (SERT + 5-HT1A partial agonism) theoretically combines the antidepressant benefit of SSRIs with the anxiolytic mechanism of buspirone in a single molecule.
- It requires a starter pack and mandatory food administration, making medication reconciliation and patient education critical to achieving therapeutic drug levels.
Safety Profile
Pregnancy use-with-caution
Lactation use-with-caution
Renal Adjustment Not required
Hepatic Adjustment Not required
TDM Not required
Concordance Terms
Cross-referenced clinical concepts — click any term to see all content where it appears.