Are Viibryd (vilazodone) and trazodone in the same class of medications?

Are Viibryd and Trazodone the Same Class?

No, Viibryd (vilazodone) and trazodone are not in the same medication class—they have distinct pharmacological classifications despite both being antidepressants that affect serotonin.

Pharmacological Classification

Vilazodone (Viibryd)

• Vilazodone is classified as a selective serotonin reuptake inhibitor (SSRI) and 5-HT1A receptor partial agonist, working by enhancing serotonergic activity through selective inhibition of serotonin reuptake with high affinity binding to 5-HT1A receptors 1
• This dual mechanism results in faster onset of action, greater efficacy, and better tolerability with reduced sexual side effects compared to traditional SSRIs 1

Trazodone

• Trazodone belongs to the class of serotonin receptor antagonists and reuptake inhibitors (SARIs), which is a distinct pharmacological category 2
• Trazodone is a triazolopyridine derivative, chemically and pharmacologically unrelated to other currently available antidepressants including SSRIs 3
• The most potent pharmacological effect of trazodone is antagonist action at 5-HT2/1C receptors, rather than serotonin reuptake inhibition 4
• Trazodone also antagonizes alpha-2 adrenergic receptors, H1 receptors, and alpha-1 adrenergic receptors, contributing to its sedative properties 1

Key Mechanistic Differences

The fundamental distinction is that vilazodone primarily works by blocking serotonin reuptake (like SSRIs), while trazodone primarily works by blocking serotonin receptors (5-HT2A/2C antagonism) 2, 4

• Vilazodone enhances serotonergic activity with no significant effects on norepinephrine or dopamine uptake 1
• Trazodone acts as an antidepressant via antagonist action at 5-HT2/1C receptors, with serotonin reuptake inhibition being a secondary mechanism 4

Clinical Implications of Different Classes

Efficacy Profiles

• Vilazodone is effective for major depressive disorder with improvement noted within 1 week and increased remission rates at 6 weeks 1
• Trazodone has demonstrated comparable antidepressant activity to tricyclic antidepressants and SSRIs, but is not effective for obsessive-compulsive disorder or panic disorder (unlike SSRIs such as fluoxetine) 4

Side Effect Profiles

• Vilazodone's most common adverse effects are diarrhea, nausea, vomiting, and insomnia, which typically resolve within 4-5 days 1
• Trazodone's most common adverse effect is drowsiness/sedation, followed by headache, dizziness, and dry mouth, with minimal anticholinergic activity 2, 5

Dosing Differences

• Vilazodone is dosed at 40 mg daily for depression 1
• Trazodone is used at lower doses (25-100 mg) for insomnia versus higher doses (up to 400 mg outpatient, 600 mg inpatient) for depression 5, 1

Common Pitfall to Avoid

Do not assume all antidepressants that affect serotonin are in the same class—the mechanism by which they affect serotonin (reuptake inhibition vs. receptor antagonism) determines their classification, side effect profile, and clinical applications 2, 4