How Viibryd (Vilazodone) Works: The Science

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Viibryd (Vilazodone): A Novel Antidepressant for Major Depressive Disorder

Viibryd (vilazodone) is a prescription medication that belongs to a class of drugs called serotonin modulators1. It is used to treat major depressive disorder (MDD), a condition characterized by persistent and severe low mood, loss of interest, and impaired functioning 2. Viibryd is taken orally once a day, usually with food 1.

Viibryd was developed by Merck KGaA, a German pharmaceutical company, under the code name EMD-68843 3. It was first tested in clinical trials in 2001, and showed promising results for the treatment of depression 3. In 2004, Merck KGaA licensed the drug to Clinical Data, Inc., a US biotechnology company, for further development and commercialization 3. In 2011, Viibryd was approved by the US Food and Drug Administration (FDA) as the first serotonin modulator for MDD1. In 2018, Viibryd was also approved by Health Canada for the same indication 4.

Viibryd is considered both a selective serotonin reuptake inhibitor (SSRI) and a serotonin (5-HT1A) receptor partial agonist 1. Serotonin is a neurotransmitter that regulates mood, emotion, cognition, and other brain functions 5. SSRIs work by blocking the reabsorption of serotonin into nerve cells, thus increasing its availability in the brain 5. Serotonin receptor partial agonists work by stimulating certain types of serotonin receptors, which may enhance or modulate the effects of serotonin 5. The exact way that Viibryd works to treat depression is not fully understood, but it is thought to involve both mechanisms of action 1.

1. In these trials, Viibryd was compared to placebo (a dummy pill) or other antidepressants over a period of 8 to 10 weeks. The primary outcome measure was the change in the Hamilton Depression Rating Scale (HAM-D), a tool that assesses the severity of depressive symptoms. The results showed that Viibryd was significantly more effective than placebo in reducing HAM-D scores in five out of seven trials. In two trials, Viibryd also showed comparable efficacy to Lexapro (escitalopram), another SSRI antidepressant.

The recommended starting dose of Viibryd is 10 mg once daily for 7 days, followed by 20 mg once daily for 7 days, then increased to 40 mg once daily as the target dose1. The dose may be adjusted by the doctor based on the patient’s response and tolerance. The maximum dose of Viibryd is 40 mg per day. Viibryd should be taken with food to improve its absorption and reduce nausea1.

Like all medications, Viibryd may cause side effects in some people. The most common side effects of Viibryd are nausea, diarrhea, vomiting, dizziness, trouble sleeping, decreased sexual interest or ability, and dry mouth 1 . These side effects are usually mild and tend to improve over time. However, some side effects may be serious and require medical attention. These include:

• Increased risk of suicidal thoughts or actions in children, adolescents, and young adults up to age 24. This risk is higher during the first few months of treatment or when the dose is changed. Patients and their caregivers should monitor for any changes in mood or behavior and report them to the doctor immediately 1 .
• Serotonin syndrome, a potentially life-threatening condition caused by too much serotonin in the body. This can occur when Viibryd is taken with other medications that affect serotonin levels, such as other antidepressants, migraine medications, opioid painkillers, herbal supplements, or illicit drugs. Symptoms of serotonin syndrome include agitation, confusion, hallucinations, fast heartbeat, high blood pressure, fever, sweating, tremors, muscle stiffness or twitching, nausea, vomiting, diarrhea, or loss of consciousness. Seek emergency medical help if you experience any of these symptoms while taking Viibryd1 .
• Bleeding problems, especially when Viibryd is taken with other medications that increase the risk of bleeding, such as aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), blood thinners, or other antidepressants. Viibryd may affect the ability of the blood to clot, which can lead to easy bruising, bleeding gums, nosebleeds, heavy menstrual bleeding, or more serious bleeding events. Tell your doctor if you have any bleeding problems or if you notice any unusual bleeding while taking Viibryd 1 .
• Mania or hypomania, a condition characterized by abnormally elevated mood, energy, activity, or impulsivity. This can occur in people who have bipolar disorder (a mood disorder that involves alternating episodes of depression and mania) or who are at risk of developing it. Viibryd may trigger or worsen manic episodes in some people. Tell your doctor if you have a history of bipolar disorder or if you experience any signs of mania while taking Viibryd, such as racing thoughts, excessive talking, decreased need for sleep, reckless behavior, or extreme irritability 1 .
• Pancreatitis, a condition that causes inflammation of the pancreas, an organ that produces digestive enzymes and hormones. This can occur in rare cases when taking Viibryd. Symptoms of pancreatitis include severe abdominal pain, nausea, vomiting, fever, or jaundice (yellowing of the skin or eyes). Stop taking Viibryd and seek medical help if you develop any of these symptoms 1 .
• Syndrome of inappropriate antidiuretic hormone secretion (SIADH), a condition that causes the body to retain too much water and lower the level of sodium in the blood. This can occur in rare cases when taking Viibryd. Symptoms of SIADH include headache, confusion, weakness, muscle cramps, seizures, or coma. Tell your doctor if you have any of these symptoms while taking Viibryd 1 .

Viibryd is not suitable for everyone and may be contraindicated in some people. Do not take Viibryd if you:

• Are allergic to vilazodone or any of the ingredients in the medication 1.
• Have taken a monoamine oxidase inhibitor (MAOI) antidepressant in the past 14 days or plan to take one in the next 14 days. This can cause a dangerous drug interaction with Viibryd. MAOIs include isocarboxazid, linezolid, phenelzine, tranylcypromine, and others 1.
• Have taken methylene blue injection in the past 14 days or plan to take it in the next 14 days. This can also cause a dangerous drug interaction with Viibryd1 .

Before taking Viibryd, tell your doctor if you:

• Have liver or kidney problems1 .
• Have a bleeding or blood clotting disorder1 .
• Have narrow-angle glaucoma1 .
• Have seizures or epilepsy1 .
• Have sexual problems1 .
• Have a history of drug abuse or addiction1 .
• Have a history of suicidal thoughts or actions1 .
• Drink alcohol1 .
• Are pregnant, planning to become pregnant, or breastfeeding1 .

Also tell your doctor about all the medications, supplements, and herbal products that you are taking or plan to take, as some of them may interact with Viibryd and affect its effectiveness or safety.

Viibryd has some advantages over other antidepressants that may make it a better choice for some people. These include:

• Novel mechanism of action. Viibryd is the first antidepressant that combines SSRI and serotonin receptor partial agonist properties. This may offer a more comprehensive and balanced modulation of serotonin signaling in the brain than other antidepressants that only target one aspect of serotonin function.
• Less emotional blunting. Some antidepressants may cause emotional blunting, which is a reduced ability to experience positive and negative emotions. This can affect the quality of life and satisfaction with treatment for some people with depression. Viibryd may cause less emotional blunting than typical SSRIs and SNRIs due to its dual action on serotonin receptors.
• Less sexual dysfunction. Some antidepressants may cause sexual dysfunction, which is a decreased interest or ability to engage in sexual activity. This can affect the self-esteem and relationships of some people with depression. Viibryd may cause less sexual dysfunction than typical SSRIs and SNRIs due to its partial agonist effect on 5-HT1A receptors, which may counteract the inhibitory effect of increased serotonin levels on sexual function.

Viibryd also has some disadvantages or limitations that may make it a less suitable option for some people. These include:

• High cost. Viibryd is a relatively new and patented drug, which means it is more expensive than older and generic antidepressants. The average retail price of Viibryd is about $400 per month, compared to about $10 per month for generic SSRIs. Although some insurance plans may cover part of the cost, many patients may still face high out-of-pocket expenses or copayments for Viibryd.
• Nausea. Viibryd is associated with a high rate of nausea, which is the most common reason for discontinuation of the drug. About 30% of patients who take Viibryd experience nausea, compared to about 10% of those who take placebo. Nausea usually occurs during the first few weeks of treatment and tends to decrease over time, but it can still be bothersome and interfere with adherence to the medication regimen. Taking Viibryd with food may help reduce nausea, but it may not eliminate it completely.
• Drug interactions. Viibryd can interact with many other medications that affect the levels or actions of serotonin or other neurotransmitters in the brain. These include other antidepressants, antipsychotics, mood stabilizers, anti-anxiety drugs, painkillers, migraine medications, herbal supplements, and illicit drugs. Some of these interactions can be dangerous and cause serious side effects such as serotonin syndrome or bleeding problems. Therefore, patients who take Viibryd should inform their doctor about all the medications they are taking or plan to take, and follow their doctor’s instructions carefully.

Viibryd is a novel antidepressant that has been shown to be effective for the treatment of major depressive disorder in adults. It has a unique mechanism of action that involves both inhibiting the reuptake of serotonin and stimulating certain serotonin receptors in the brain. It may have some benefits over other antidepressants in terms of causing less emotional blunting and sexual dysfunction. However, it also has some drawbacks such as high cost, nausea, and drug interactions. Therefore, the decision to use Viibryd should be based on a careful evaluation of the individual patient’s needs, preferences, and medical history, as well as a discussion with their doctor about the potential risks and benefits of the medication.

1. Viibryd (vilazodone) Prescribing Information. Forest Pharmaceuticals, Inc. Revised 01/2020.
2. Major Depressive Disorder: Symptoms, Causes, and Treatment. WebMD. Updated 09/17/2019.
3. Vilazodone: A Review in Major Depressive Disorder. Drugs. 2015;75(4):403-413.
4. Viibryd (vilazodone) Product Monograph. Allergan Inc. Revised 07/31/2018.
5. Vilazodone: A New Treatment Option for Major Depressive Disorder. The Mental Health Clinician. 2012;2(1):15-19.
6. Sexual Dysfunction Associated With Antidepressant Treatment. Current Psychiatry Reports. 2019;21(11):106.
7. Viibryd Prices, Coupons & Savings Tips. GoodRx. Accessed 08/23/2023.