Vilazodone

Vilazodone is a serotonin reuptake inhibitor (SSRI) and partial serotonin (5-HT1A) receptor agonist that is used in treatment of major depressive disorder ¹, ², ³, ⁴, ⁵, ⁶. Vilazodone is an antidepressant that is thought to work through the modulation of serotonin neurotransmission in the central nervous system (brain and spinal cord), including the inhibition of serotonin reuptake at the serotonin transporter (SERT), an increased amount of serotonin (5-hydroxytryptamine or 5HT) remains in the synaptic cleft and can stimulate postsynaptic receptors for a more extended period ⁷. Because of these characteristics, vilazodone has been termed a serotonin partial agonist–reuptake inhibitor (SPARI) ⁷, ⁴.

Vilazodone was approved for use in the United States in 2011 for use in treatment of major depressive disorder ⁸, ⁹, ⁵. However, there is limited clinical experience with its use.

Vilazodone is available as tablets of 10, 20 and 40 mg under the brand name Viibryd ⁹. Take vilazodone at around the same time every day. The recommended starting dosage of vilazodone in adults is 10 mg per day for adults younger than 65 years of age, and 5 mg per day for adults 65 and older, which can then be increased to the typical maintenance dose of 40 mg once daily. Vilazodone is usually taken with food once a day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take vilazodone exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Your doctor will probably start you on a low dose of vilazodone and gradually increase your dose, not more than once every 7 days.

Vilazodone controls depression but does not cure it. It may take several weeks before you feel the full benefit of vilazodone. Continue to take vilazodone even if you feel well. Do not stop taking vilazodone without talking to your doctor. Your doctor will probably decrease your dose gradually. If you suddenly stop taking vilazodone, you may experience withdrawal symptoms such as dizziness; nausea; headache; confusion; irritability; agitation; difficulty falling asleep or staying asleep; anxiety; extreme tiredness; seizures; pain, burning, or tingling in the hands or feet; frenzied or abnormally excited mood; or sweating. Tell your doctor if you experience any of these symptoms while you are decreasing your dose of vilazodone or soon after you stop taking vilazodone.

Common, non-serious side effects of Vilazodone include diarrhea, nausea, fatigue, drowsiness, headache, insomnia, weight gain and sexual dysfunction. Vilazodone overdose is associated with acute serotonin syndrome. Rare, but potentially severe adverse effects include suicidal thinking and behavior, activation of symptoms of mania, serotonin syndrome, sexual dysfunction, hyponatremia and hypersensitivity reactions.

Vilazodone mechanism of action

The mechanism of the antidepressant effect of Vilazodone is thought to be related to its enhancement of serotonergic activity in the brain through selective inhibition of serotonin reuptake ⁷. Vilazodone binds with high affinity to the serotonin reuptake site but not to the norepinephrine or dopamine reuptake site. As a result, vilazodone potently and selectively inhibits the reuptake of serotonin ⁴.

Even though vilazodone is also a partial agonist at serotonergic 5-HT1A receptors, the net result of this activity on serotonergic transmission and its role in the antidepressant effect of vilazodone are not fully understood ⁴.

The half-life of vilazodone is approximately 25 hours ⁴.

When vilazodone is taken with food, the drug’s absolute bioavailability is 72% ⁴. After daily dosing of vilazodone 40 mg under fed conditions, the mean maximum plasma concentration (Cmax) at steady state was 156 ng/mL, and the mean area-under-the-curve (AUC 0–24 hr) concentration was 1,645 ng • hours/mL. When vilazodone was administered with a high-fat or light meal, the mean maximum plasma concentration (Cmax) was increased by approximately 147% to 160%, and the area-under-the-curve concentration was increased by approximately 64% to 85% ⁴.

If vomiting occurs within 7 hours after administration, vilazodone’s absorption is decreased by about 25%; however, a replacement dose is not required ⁴.

Vilazodone has a large volume of distribution (value unknown). It is approximately 96% to 99% protein-bound ⁴.

Vilazodone is extensively metabolized in the liver, primarily via the cytochrome P450 (CYP) 3A4 isoenzyme. CYP2C19 and CYP2D6 are minor metabolic pathways. Non-CYP450 metabolism also occurs, possibly by carboxylesterase. Only 1% and 2% of the dose are recovered in urine and feces, respectively, as unchanged vilazodone.

The presence of mild or moderate kidney and liver impairment does not affect the clearance of vilazodone ⁴.

Vilazodone Contraindications

Because of the risk of serious, sometimes fatal, interactions with serotonergic drugs, vilazodone is contraindicated in patients taking concomitant monoamine oxidase (MAO) inhibitors or in those who have taken them within 14 days preceding vilazodone therapy ⁴.

What is vilazodone used for?

Vilazodone is a serotonin reuptake inhibitor (SSRI) and partial serotonin (5-HT1A) receptor agonist that is used to treat major depressive disorder ¹, ², ³, ⁴, ⁵, ⁶, ¹⁰, ¹¹, ¹², ¹³, ¹⁴, ¹⁵, ¹⁶.

Before taking Vilazodone

Before taking vilazodone:

• Tell your doctor and pharmacist if you are allergic to vilazodone, any other medications, or any of the ingredients in vilazodone tablets. Ask your pharmacist or check the Medication Guide for a list of the ingredients.
• Do not use an monoamine oxidase (MAO) inhibitor within 14 days before or 14 days after you take vilazodone. A dangerous drug interaction could occur. Monoamine oxidase (MAO) inhibitors include isocarboxazid (Marplan), linezolid (Zyvox), methylene blue, rasagiline, phenelzine (Nardil), selegiline (Emsam, Zelapar), and tranylcypromine (Parnate). You must wait at least 14 days after stopping an monoamine oxidase (MAO) inhibitor before you take vilazodone.
• Tell your doctor if you also take stimulant medicine, opioid medicine, herbal products, or medicine for depression, mental illness, Parkinson’s disease, migraine headaches, serious infections, or prevention of nausea and vomiting. An interaction with vilazodone could cause a serious condition called serotonin syndrome.
• Vilazodone is not approved for use by anyone younger than 18 years old.
• Some young people have thoughts about suicide when first taking an antidepressant. Your doctor should check your progress at regular visits. Your family or other caregivers should also be alert to changes in your mood or symptoms.
• Some medications should not be taken with vilazodone. Other medications may cause dosing changes or extra monitoring when taken with vilazodone. Make sure you have discussed any medications you are currently taking or plan to take before starting vilazodone with your doctor and pharmacist. Before starting, stopping, or changing any medications while taking vilazodone, please get the advice of your doctor or pharmacist.
• The following nonprescription or herbal products may interact with vilazodone: St. John’s wort; tryptophan; aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil, Motrin) and naproxen (Aleve). Be sure to let your doctor and pharmacist know that you are taking these medications before you start taking vilazodone. Do not start any of these medications while taking vilazodone without discussing with your doctor.
• Tell your doctor if you have a low level of sodium in your blood (hyponatremia) or glaucoma (increased pressure in the eye that may cause loss of sight), and if you drink or have ever drunk large amounts of alcohol, Also tell your doctor if you have or have ever had bleeding problems, seizures, or liver disease.
• Tell your doctor if you are pregnant, especially if you are in the last few months of your pregnancy, or if you plan to become pregnant or are breast-feeding. If you become pregnant while taking vilazodone, call your doctor. Vilazodone may cause problems in newborns following delivery if it is taken during the last months of pregnancy. If you are pregnant, your name may be listed on a pregnancy registry to track the effects of vilazodone on the baby.
• If you are having surgery, including dental surgery, tell the doctor or dentist that you are taking vilazodone.
• You should know that vilazodone may make you drowsy and affect your judgment and thinking. Do not drive a car or operate machinery until you know how this medication affects you.
• Ask your doctor about the safe use of alcoholic beverages while you are taking vilazodone. Alcohol can make the side effects from vilazodone worse.
• You should know that vilazodone may cause angle-closure glaucoma (a condition where the fluid is suddenly blocked and unable to flow out of the eye causing a quick, severe increase in eye pressure which may lead to a loss of vision). Talk to your doctor about having an eye examination before you start taking this medication. If you have nausea, eye pain, changes in vision, such as seeing colored rings around lights, and swelling or redness in or around the eye, call your doctor or get emergency medical treatment right away.

Tell your doctor about all your current medicines. Many drugs can affect vilazodone, especially:

• any other antidepressants
• mephenytoin
• St. John’s wort
• tramadol
• a diuretic or “water pill”
• medicine to treat anxiety, mood disorders, or mental illness such as schizophrenia
• a blood thinner: warfarin, Coumadin, Jantoven
• migraine headache medicine: sumatriptan, Imitrex, Maxalt, Treximet, and others.

This list is not complete and many other drugs may affect vilazodone. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Pregnancy

It is not known if vilazodone can make it harder to get pregnant ¹⁷.

Miscarriage is common and can occur in any pregnancy for many different reasons. Studies have not been done to see if vilazodone increases the chance for miscarriage. However, depression itself might increase the chance for miscarriage.

Every pregnancy starts out with a 3-5% chance of having a birth defect. This is called the background risk. Animal studies did not find an increased chance of birth defects. We have been unable to locate studies on the use of vilazodone in human pregnancies.

Studies have not been done to see if vilazodone can cause other pregnancy-related problems, such as preterm delivery (birth before week 37) or low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth).

It is not known if the use of vilazodone during pregnancy can cause withdrawal symptoms in a baby after birth. The use of other antidepressants during pregnancy has been associated with temporary symptoms in some newborns after birth. These symptoms are sometimes referred to as withdrawal. Symptoms may include jitteriness, increased muscle tone, irritability, changes in sleep patterns, tremors, trouble eating, and trouble breathing. These symptoms are usually mild and go away on their own. Some babies may need to stay in a special care nursery for several days. Not all babies exposed to an antidepressant will have these symptoms. It is important that your doctor know you are taking vilazodone so that if symptoms occur your baby can get the best care.

Studies have not been done to see if vilazodone use in pregnancy can cause behavior or learning issues for the child.

Breastfeeding

It is not known if vilazodone gets into breast milk or causes side effects for a baby who receives the milk. The benefit of continuing vilazodone while breastfeeding may outweigh the risks of an untreated mental health condition or the risks of not breastfeeding. Your doctor can talk with you about vilazodone and what treatment is best for you. Be sure to talk to your doctor about all of your breastfeeding questions.

Vilazodone dosage

Adult Dose for Depression

• Initial dose: 10 mg orally once a day for 7 days, followed by 20 mg orally once a day for an additional 7 days
• Maintenance dose: 40 mg orally once a day

Take vilazodone with food ¹⁸.

Missed Dose

If you miss a dose of vilazodone, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Monitoring

Patients who are taking vilazodone should be monitored for clinical worsening and for suicidal thinking or behavior, especially during the initial few months and at times of dose increases or decreases).

Serotonergic drugs such as vilazodone have been associated with withdrawal symptoms upon discontinuation, including dysphoric mood, irritability, agitation, anxiety, and confusion. Patients should be monitored for these symptoms when discontinuing vilazodone.

The most severe form of serotonin syndrome resembles neuroleptic malignant syndrome (NMS) and is characterized by hyperthermia, muscle rigidity, autonomic instability with possible rapid fluctuation of vital signs, and alterations in mental status. Patients should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome (NMS) -like signs and symptoms.

Because of the potential for increased bleeding, patients receiving warfarin therapy should be carefully monitored when vilazodone is initiated or discontinued.

Vilazodone side effects

Vilazodone may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• diarrhea (28%)
• nausea (23%)
• insomnia (6%)
• vomiting (5%)
• dizziness
• dry mouth
• fatigue
• unusual dreams
• joint pain (arthralgia)
• palpitations
• decreased appetite
• heartburn
• gas
• pain, burning, or tingling in the hands or feet
• uncontrollable shaking of a part of the body
• tiredness
• sexual problems in males; decreased sex drive, inability to get or keep an erection, or delayed or absent ejaculation
• sexual problems in females; decreased sex drive, or delayed orgasm or unable to have an orgasm

Some side effects can be serious. If you experience any of these symptoms or those listed in the IMPORTANT WARNING or SPECIAL PRECAUTIONS sections, see your doctor immediately:

• rash
• hives
• swelling
• difficulty breathing
• loss of consciousness
• seizures
• fever, sweating, confusion, fast or irregular heartbeat, and severe muscle stiffness or twitching, agitation, hallucinations, loss of coordination, nausea, vomiting, or diarrhea
• unusual bleeding or bruising
• nosebleeds
• small red or purple dots on the skin
• hallucinations (seeing things or hearing voices that do not exist)
• headache
• difficulty concentrating
• memory problems
• weakness
• problems with coordination
• increased falls
• fainting

Vilazodone may cause other side effects. See your doctor if you have any unusual problems while taking Vilazodone.

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