Usage
- Vilazodone is prescribed for the treatment of Major Depressive Disorder (MDD) in adults.
- Pharmacological classification: Vilazodone is classified as a serotonin partial agonist and reuptake inhibitor (SPARI). It is considered an atypical antidepressant.
- Mechanism of Action: Vilazodone enhances serotonin levels in the brain by inhibiting serotonin reuptake and partially activating serotonin 5-HT1A receptors. This combined action is thought to contribute to its antidepressant effect.
Alternate Names
- International Nonproprietary Name (INN): Vilazodone hydrochloride
- Brand Names: Viibryd
How It Works
- Pharmacodynamics: Vilazodone’s primary mechanism of action is the combination of serotonin reuptake inhibition and 5-HT1A receptor partial agonism. This leads to increased serotonin levels in the synaptic cleft, which is believed to improve mood and alleviate depressive symptoms.
- Pharmacokinetics:
- Absorption: Vilazodone is well-absorbed after oral administration, particularly when taken with food. Food increases its bioavailability.
- Metabolism: Primarily metabolized in the liver via multiple pathways, including CYP3A4.
- Elimination: Excreted mainly through the kidneys. The elimination half-life is approximately 25 hours.
- Mode of Action: At the cellular level, vilazodone binds to the serotonin transporter (SERT), blocking the reuptake of serotonin from the synaptic cleft. It also acts as a partial agonist at the 5-HT1A receptor.
- Receptor binding, enzyme inhibition, or neurotransmitter modulation: Vilazodone inhibits SERT and partially activates the 5-HT1A receptor.
- Elimination pathways: Primarily renal excretion with hepatic metabolism involving CYP3A4.
Dosage
Standard Dosage
Adults:
- Initial dose: 10 mg orally once daily with food for 7 days.
- Usual dose: 20 mg to 40 mg orally once daily with food.
- Titration: Increase from 20 mg to 40 mg after at least 7 days, based on individual patient response and tolerability.
- Maximum dose: 40 mg/day in most cases; however, some clinicians may prescribe up to 80mg based on individual patient needs.
Children:
- Vilazodone is not approved for use in children. Safety and efficacy have not been established in this population.
Special Cases:
- Elderly Patients: No dose adjustment is generally recommended based on age alone. However, starting at the lower end of the dosing range and careful titration are advised.
- Patients with Renal Impairment: No dose adjustment is typically necessary.
- Patients with Hepatic Dysfunction: No dose adjustment is usually required for mild to moderate impairment. Vilazodone has not been studied in patients with severe hepatic impairment.
- Patients with Comorbid Conditions: Caution is advised in patients with bipolar disorder, as vilazodone can trigger mania or hypomania. Careful monitoring is also recommended in patients with a history of seizures.
Clinical Use Cases
Vilazodone is specifically indicated for the treatment of Major Depressive Disorder. It does not have specific dosage recommendations for procedures such as intubation, surgical operations, mechanical ventilation, ICU use, or emergency situations. Other medications are typically used in these settings.
Dosage Adjustments
- Concomitant CYP3A4 Inhibitors: When co-administered with strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, clarithromycin), the vilazodone dose should not exceed 20 mg daily.
- Concomitant CYP3A4 Inducers: In patients taking strong CYP3A4 inducers (e.g., carbamazepine, rifampin), the dose may be increased (up to a maximum of 80 mg/day), based on clinical response, over 1-2 weeks. The dose should be tapered down upon discontinuation of the inducer.
Side Effects
Common Side Effects
- Diarrhea
- Nausea
- Insomnia
- Vomiting
- Dizziness
- Dry mouth
Rare but Serious Side Effects
- Serotonin syndrome (symptoms may include high fever, agitation, confusion, muscle rigidity, tremors)
- Suicidal thoughts or behaviors (especially in young adults)
- Hyponatremia (low sodium levels in the blood)
- Bleeding problems (especially with concomitant use of anticoagulants or NSAIDs)
- Manic episodes (in patients with bipolar disorder)
- Seizures
- Allergic reactions
Long-Term Effects
The long-term effects of vilazodone are still being studied. However, potential concerns include sexual dysfunction, which may persist even after discontinuation of the drug.
Adverse Drug Reactions (ADR)
Clinically significant ADRs primarily include serotonin syndrome, suicidal ideation, and hyponatremia. These require prompt medical intervention.
Contraindications
- Concomitant use of Monoamine Oxidase Inhibitors (MAOIs). A 14-day washout period is required between discontinuing an MAOI and starting vilazodone, and vice versa.
- Hypersensitivity to vilazodone or any of its components.
Drug Interactions
- MAOIs: Concomitant use is contraindicated due to the risk of serotonin syndrome.
- Serotonergic drugs: (e.g., SSRIs, SNRIs, triptans) Increased risk of serotonin syndrome.
- CYP3A4 inhibitors: Increased vilazodone levels. Dose adjustment may be needed.
- CYP3A4 inducers: Decreased vilazodone levels. Dose adjustment may be needed.
- Anticoagulants/antiplatelet drugs: Increased risk of bleeding.
- Alcohol: Concomitant use is not recommended due to potential additive CNS depressant effects.
- Triptans: Increased risk of serotonin syndrome. Close monitoring is advised if concomitant use is necessary.
Pregnancy and Breastfeeding
- Pregnancy Safety Category: Category C. Vilazodone has shown some developmental toxicity in animal studies but not in human studies. Use only if the potential benefit outweighs the risk to the fetus.
- Breastfeeding: It is unknown if vilazodone passes into breast milk. The decision to breastfeed should be made in consultation with a physician, weighing the potential risks to the infant against the benefits of breastfeeding for both the mother and child.
Drug Profile Summary
- Mechanism of Action: Serotonin reuptake inhibitor and 5-HT1A receptor partial agonist.
- Side Effects: Common: Diarrhea, nausea, insomnia. Serious: Serotonin syndrome, suicidal thoughts, hyponatremia.
- Contraindications: Concomitant MAOI use, hypersensitivity.
- Drug Interactions: MAOIs, serotonergic drugs, CYP3A4 inhibitors/inducers, anticoagulants.
- Pregnancy & Breastfeeding: Use with caution. Consult a physician.
- Dosage: 10 mg initially, titrated to 20-40 mg daily with food. Maximum 40 mg (or up to 80 mg in some cases).
- Monitoring Parameters: Monitor for mood changes, suicidal ideation, signs of serotonin syndrome, and hyponatremia.
Popular Combinations
Vilazodone is not typically used in combination with other antidepressants. If combination therapy is required, careful monitoring for adverse effects, especially serotonin syndrome, is crucial. Augmentation with other agents, such as bupropion or buspirone, might be considered in select cases.
Precautions
- General Precautions: Screen for bipolar disorder, history of seizures, bleeding disorders, and glaucoma.
- Specific Populations:
- Pregnant Women: Weigh risks and benefits carefully.
- Breastfeeding Mothers: Potential risk to infant.
- Children & Elderly: Not recommended for children. Use with caution in the elderly.
- Lifestyle Considerations: Avoid alcohol. Use caution when operating machinery.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Vilazodone?
A: Initial dose: 10mg once daily with food for 7 days, then increase to 20mg daily. Maintenance dose: 20-40mg once daily with food. Maximum dose is generally 40mg/day, but may be increased up to 80mg/day in certain situations.
Q2: What are the most common side effects of Vilazodone?
A: Diarrhea, nausea, insomnia, and vomiting are the most common side effects.
Q3: Can Vilazodone be used with MAOIs?
A: No, Vilazodone is contraindicated with concomitant MAOI use due to the risk of serotonin syndrome.
Q4: Is Vilazodone safe during pregnancy?
A: Vilazodone is a Pregnancy Category C drug. There are limited data in humans. Use only if the potential benefit justifies the potential risk to the fetus.
Q5: How should Vilazodone be taken?
A: Vilazodone should be taken orally once daily with food.
Q6: What should I do if I miss a dose of Vilazodone?
A: Take the missed dose as soon as you remember, unless it is close to the time for your next dose. Do not take two doses at the same time.
Q7: How long does it take for Vilazodone to work?
A: Therapeutic response is typically seen after 1-2 weeks of treatment.
Q8: Can Vilazodone cause weight gain?
A: While weight gain is a possible side effect, it is reported less frequently with vilazodone compared to some other antidepressants.
Q9: What are the signs of serotonin syndrome?
A: Agitation, confusion, rapid heart rate, high fever, sweating, muscle rigidity or twitching, loss of coordination, and seizures. If these occur, seek immediate medical attention.
Q10: What are the symptoms of hyponatremia?
A: Symptoms can include confusion, headache, difficulty concentrating, memory problems, weakness, and unsteadiness. It’s crucial to monitor patients, especially the elderly and those taking diuretics, for these symptoms.
