Vilazodone

DEA NFLIS-Drug Category -> Antidepressants

Pharmaceuticals -> Listed in ZINC15

Antidepressants -> Selective serotonin reuptake inhibitors (SSRI)

Breast Feeding; Lactation; Milk, Human; Antidepressive Agents; Serotonin Uptake Inhibitors

The Approved Drug Products with Therapeutic Equivalence Evaluations identifies currently marketed prescription drug products, including vilazodone hydrochloride, approved on the basis of safety and effectiveness by FDA under sections 505 of the Federal Food, Drug, and Cosmetic Act. /Vilazodone hydrochloride/

Extinguishing media: Water spray- Carbon dioxide, dry chemical powder, or appropriate foam. Special protective equipment for firefighters: Wear self-contained breathing apparatus and protective clothing to prevent contact with skin and eyes. /Vilazodone hydrochloride/

Procedure(s) of personal percaution(s): Wear respirator, chemical safety goggles, rubber boots, and heavy rubber gloves. Methods for cleaning up: Sweep up, place in a bag and hold for waste disposal. Avoid raising dust. Ventilate area and wash spill site after material pickup is complete. /Vilazodone hydrochloride/

SRP: Expired or waste pharmaceuticals shall carefully take into consideration applicable DEA, EPA, and FDA regulations. It is not appropriate to dispose by flushing the pharmaceutical down the toilet or discarding to trash. If possible return the pharmaceutical to the manufacturer for proper disposal being careful to properly label and securely package the material. Alternatively, the waste pharmaceutical shall be labeled, securely packaged and transported by a state licensed medical waste contractor to dispose by burial in a licensed hazardous or toxic waste landfill or incinerator.

Concomitant administration of vilazodone and moderate CYP3A4 inhibitors (e.g., erythromycin) can result in increased plasma vilazodone concentrations. During concurrent administration with moderate inhibitors of CYP3A4 (e.g., erythromycin), the dosage of vilazodone should be reduced to 20 mg once daily in patients experiencing intolerable adverse effects.

Concomitant administration of vilazodone and potent CYP3A4 inhibitors (e.g., clarithromycin, ketoconazole) can increase plasma vilazodone concentrations by approximately 50%. The manufacturer states that the dosage of vilazodone should be reduced to 20 mg once daily if administered concomitantly with a potent CYP3A4 inhibitor.

Potentially serious, sometimes fatal adverse reactions may occur in patients who are receiving or have recently received a monoamine oxidase (MAO) inhibitor and then initiate therapy with antidepressant(s) that are pharmacologically similar to vilazodone (e.g., SSRIs), or in those who received SSRI therapy shortly before initiation of an MAO inhibitor. Concomitant use of MAO inhibitors with vilazodone is contraindicated. In addition, at least 2 weeks should elapse between discontinuance of an MAO inhibitor and initiation of vilazodone and vice versa.

Linezolid, an anti-infective agent that is also a reversible MAO inhibitor, has been associated with drug interactions resulting in serotonin syndrome, including some associated with SSRIs. Because of this potential risk, linezolid generally should not be used in patients receiving vilazodone. While the US Food and Drug Administration (FDA) has not received reports of serotonin syndrome with concomitant use of linezolid and vilazodone to date, the risk is considered comparable to that with SSRIs. However, the FDA states that certain life-threatening or urgent situations may necessitate immediate linezolid treatment in a patient receiving a serotonergic drug. In such emergency situations, the availability of alternative anti-infectives should be considered and the benefits of linezolid should be weighed against the risk of serotonin syndrome. If linezolid is indicated in such emergency situations, vilazodone must be immediately discontinued and the patient monitored for symptoms of CNS toxicity for 2 weeks or until 24 hours after the last linezolid dose, whichever comes first. Treatment with vilazodone may be resumed 24 hours after the last linezolid dose. If nonemergency use of linezolid is being planned for a patient receiving vilazodone, vilazodone should be withheld for at least 2 weeks prior to initiating linezolid. Treatment with vilazodone should not be initiated in a patient receiving linezolid; when necessary, vilazodone may be started 24 hours after the last linezolid dose.

For more Interactions (Complete) data for Vilazodone (13 total), please visit the HSDB record page.

IDENTIFICATION AND USE: Vilazodone is a white to off-white solid that is formulated into film-coated tablets. Vilazodone is a combined selective serotonin-reuptake inhibitor and serotonin type 1-A (5-hydroxytryptamine (5-HT1A) receptor partial agonist. It is used for the treatment of major depressive disorder in adults. HUMAN EXPOSURE AND TOXICITY: In clinical trials toxic effects of vilazodone at 200-280 mg included serotonin syndrome, lethargy, restlessness, hallucinations, and disorientation. Serotonin syndrome, a potentially life-threatening toxicity has also been reported at therapeutic doses. Serotonin syndrome symptoms may include mental status changes (agitation, hallucinations, delirium, and coma), autonomic instability (tachycardia, labile blood pressure, dizziness, diaphoresis, flushing, hyperthermia), neuromuscular symptoms (tremor, rigidity, myoclonus, hyperreflexia, incoordination), seizures, and/or gastrointestinal symptoms (nausea, vomiting, diarrhea). While serotonin syndrome has been reported during vilazodone monotherapy, it is a particular concern when used with other serotonergic drugs and with drugs that impair metabolism of serotonin (in particular, monamine oxidase inhibitors (MAOIs). The concomitant use of vilazdone with MAOIs intended to treat psychiatric disorders is contraindicated. Vilazodone is also not approved for use in pediatric patients. Pooled analyses of short-term placebo-controlled studies of antidepressant drugs (selective serotonin reuptake inhibitors and others) showed that these drugs increase the risk of suicidal thinking and behavior in children, adolescents, and young adults with major depressive disorder and other psychiatric disorders. Also, some neonates exposed to serotonegic antidepressants (including vilazodone) late in the third trimester of pregnancy have developed complications requiring prolonged hospitalization, respiratory support, and tube feeding. Such complications can arise immediately upon delivery. Reported clinical findings have included respiratory distress, cyanosis, apnea, seizures, temperature instability, feeding difficulty, vomiting, hypoglycemia, hypotonia, hypertonia, hyperreflexia, tremor, jitteriness, irritability, and constant crying. In some cases, the clinical picture is consistent with serotonin syndrome. Infants exposed to vilazodone in pregnancy may also have an increased risk for persistent pulmonary hypertension of the newborn, a rare heart and lung condition associated with substantial neonatal morbidity and mortality. ANIMAL STUDIES: Vilazodone caused some developmental toxicity in rats, but was not teratogenic in rats or rabbits. When vilazodone was administered to pregnant rats at an oral dose of 30 times the maximum recommended human dose during the period of organogenesis and throughout pregnancy and lactation, the number of live born pups was decreased. There was an increase in early postnatal pup mortality, and among surviving pups there was decreased body weight, delayed maturation, and decreased fertility in adulthood. There was some maternal toxicity at this dose.

/SIGNS AND SYMPTOMS/ There is limited clinical experience regarding human overdosage with Viibryd. Four patients and 1 patient's child experienced an overdose of Viibryd; all recovered. The adverse reactions associated with overdose of Viibryd at doses of 200-280 mg as observed in clinical trials included serotonin syndrome, lethargy, restlessness, hallucinations, and disorientation.

/SIGNS AND SYMPTOMS/ Potentially life-threatening serotonin syndrome or neuroleptic malignant syndrome (NMS)-like reactions have been reported with antidepressants alone, but particularly with concurrent use of other serotonergic drugs (including serotonin (5-hydroxytryptamine; 5-HT) type 1 receptor agonists (triptans)), drugs that impair the metabolism of serotonin (e.g., MAO inhibitors), or antipsychotics or other dopamine antagonists. Manifestations of serotonin syndrome may include mental status changes (e.g., agitation, hallucinations, coma), autonomic instability (e.g., tachycardia, labile blood pressure, hyperthermia), neuromuscular aberrations (e.g., hyperreflexia, incoordination), and/or GI symptoms (e.g., nausea, vomiting, diarrhea). In its most severe form, serotonin syndrome may resemble NMS, which is characterized by hyperthermia, muscle rigidity, autonomic instability with possible rapid fluctuation in vital signs, and mental status changes. Patients receiving vilazodone should be monitored for the development of serotonin syndrome or NMS-like signs and symptoms. Concurrent or recent (i.e., within 2 weeks) therapy with MAO inhibitors intended to treat depression is contraindicated. If concurrent therapy with vilazodone and a 5-HT1 receptor agonist (triptan) is clinically warranted, the patient should be observed carefully, particularly during initiation of therapy, when dosage is increased, or when another serotonergic agent is initiated. Concomitant use of vilazodone and serotonin precursors (e.g., tryptophan) is not recommended. If signs and symptoms of serotonin syndrome or NMS occur, treatment with vilazodone and any concurrently administered serotonergic or antidopaminergic agents, including antipsychotic agents, should be immediately discontinued and supportive and symptomatic treatment initiated.

/SIGNS AND SYMPTOMS/ Infants exposed to selective serotonin-reuptake inhibitors (SSRIs) in pregnancy may have an increased risk for persistent pulmonary hypertension of the newborn (PPHN). PPHN occurs in 1-2 per 1,000 live births in the general population and is associated with substantial neonatal morbidity and mortality. Several recent epidemiologic studies suggest a positive statistical association between SSRI use (including Viibryd) in pregnancy and PPHN. Other studies do not show a significant statistical association.

/SIGNS AND SYMPTOMS/ Neonates exposed to Viibryd and other selective serotonin-reuptake inhibitors (SSRIs) or serotonin and norepinephrine reuptake inhibitors (SNRIs), late in the third trimester have developed complications requiring prolonged hospitalization, respiratory support, and tube feeding. Such complications can arise immediately upon delivery. Reported clinical findings have included respiratory distress, cyanosis, apnea, seizures, temperature instability, feeding difficulty, vomiting, hypoglycemia, hypotonia, hypertonia, hyperreflexia, tremor, jitteriness, irritability, and constant crying. These features are consistent with either a direct toxic effect of SSRIs and SNRIs or, possibly, a drug discontinuation syndrome. It should be noted that, in some cases, the clinical picture is consistent with serotonin syndrome

For more Human Toxicity Excerpts (Complete) data for Vilazodone (6 total), please visit the HSDB record page.

/LABORATORY ANIMALS: Developmental or Reproductive Toxicity/ When vilazodone was administered to pregnant rats at an oral dose of 30 times the MRHD during the period of organogenesis and throughout pregnancy and lactation, the number of live born pups was decreased. There was an increase in early postnatal pup mortality, and among surviving pups there was decreased body weight, delayed maturation, and decreased fertility in adulthood. There was some maternal toxicity at this dose. These effects were not seen at 6 times the MRHD.

/LABORATORY ANIMALS: Developmental or Reproductive Toxicity/ No teratogenic effects were observed when vilazodone was given to pregnant rats or rabbits during the period of organogenesis at oral doses up to 200 and 36 mg/kg/day, respectively. These doses are 48 and 17 times, in rats and rabbits, respectively, the maximum recommended human dose (MRHD) of 40 mg on a mg/m2 basis. Fetal body weight gain was reduced, and skeletal ossification was delayed in both rats and rabbits at these doses; these effects were not observed at doses up to 10 times the MRHD in rats or 4 times the MRHD in rabbits.

/ALTERNATIVE and IN VITRO TESTS/ Vilazodone is a novel compound with combined high affinity and selectivity for the 5-hydroxytryptamine (5-HT) transporter and 5-HT(1A) receptors.Vilazodone was tested as a prototype compound, which benefits from dual pharmacological effects that could increase extracellular 5-HT to levels higher than those produced by conventional selective serotonin reuptake inhibitors (SSRIs). In Sf9 cells, vilazodone increased guanosine 5'-O-(3-[(35)S]thiotriphosphate) binding to 69% of the magnitude of the full 5-HT(1A) receptor agonist R-(1)-trans-8-hydroxy-2-[N-n-propyl-N-(39-iodo-29-propenyl)] aminotetralin (8-OH-PIPAT), indicating that it is a partial agonist at 5-HT(1A) receptors. Acute, systemic administration of vilazodone produced a larger maximal increase of extracellular 5-HT than the SSRI fluoxetine in both the ventral hippocampus (HPv) (558 versus 274%) and the frontal cortex (FC) (527 versus 165%). Regional differences in the response to the two drugs were also observed. These effects may be attributed to the differential regulation of 5-HT release in the HPv and FC by 5-HT(1A) autoreceptors. When challenged with the 5-HT(1A) receptor agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT), vilazodone-induced increases in extracellular 5-HT were greatly reduced in the HPv but to a lesser extent in the FC. In behavioral studies, vilazodone produced antidepressant-like effects in the forced swimming test in both rats and mice but only within a narrow dosage range. Like fluoxetine, vilazodone did not produce the symptoms of the 5-HT behavioral syndrome in rats but, unlike fluoxetine, pretreatment with vilazodone blocked expression of the 5-HT behavioral syndrome induced by 8-OH-DPAT. Taken together, the results show that vilazodone augments extracellular 5-HT levels in forebrain regions to a greater extent than fluoxetine. At higher doses, however, weak efficacy of vilazodone at postsynaptic 5-HT(1A) receptors may inhibit the expression of rodent antidepressant-like behaviors.

/OTHER TOXICITY INFORMATION/ Vilazodone has been reported to be an inhibitor of 5-hydoxytryptamine (5-HT) reuptake and a partial agonist at 5-HT1A receptors. Using [35S]GTPgammaS binding in rat hippocampal tissue, vilazodone was demonstrated to have an intrinsic activity comparable to the 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT). Vilazodone (1-10 mg/kg p.o.) dose-dependently displaced in vivo [3H]DASB (N,N-dimethyl-2-(2-amino-4-cyanophenylthio)benzylamine) binding from rat cortex and hippocampus, indicating that vilazodone occupies 5-HT transporters in vivo. Using in vivo microdialysis, vilazodone (10 mg/kg p.o.) was demonstrated to cause a 2-fold increase in extracellular 5-HT but no change in noradrenaline or dopamine levels in frontal cortex of freely moving rats. In contrast, administration of 8-OH-DPAT (0.3 mg/kg s.c.), either alone or in combination with a serotonin specific reuptake inhibitor (SSRI; paroxetine, 3 mg/kg p.o.), produced no increase in cortical 5-HT whilst increasing noradrenaline and dopamine 2 and 4 fold, respectively. A 2-fold increase in extracellular 5-HT levels (but no change in noradrenaline or dopamine levels) was observed after combination of the 5-HT(1A) receptor antagonist, N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(pyridinyl)cyclohexanecarboxamide) (WAY-100635; 0.3 mg/kg s.c.) and paroxetine (3 mg/kg p.o.). In summary, vilazodone behaved as a high efficacy partial agonist at the rat hippocampal 5-HT1A receptors in vitro and occupied 5-HT transporters in vivo. In vivo vilazodone induced a selective increase in extracellular levels of 5-HT in the rat frontal cortex. This profile was similar to that seen with a 5-HT1A receptor antagonist plus an SSRI but in contrast to 8-OH-DPAT either alone or in combination with paroxetine.

/OTHER TOXICITY INFORMATION/ The recently approved antidepressant vilazodone, a serotonin (5-HT)1A receptor partial agonist/selective 5-HT reuptake inhibitor offers new possibilities to study the underlying mechanisms of depression pharmacotherapy and of 5-HT augmenting antidepressants. ... 5-HT levels /were measured/ in two subregions of the rat prefrontal cortex by microdialysis, and 5-hydroxytryptophan (5-HTP) accumulation and tissue 5-HT concentrations ex vivo. Vilazodone-induced maximal 5-HT levels were similar in the medial and the lateral cortex and were up to sixfold higher than those induced by paroxetine, citalopram, or fluoxetine tested in parallel. Depolarization/autoreceptor-insensitive 5-HT release by vilazodone could be excluded. The citalopram (1 uM, locally infused)-induced increase of 5-HT was further increased by vilazodone (1 mg/kg i.p.), but not by citalopram (10 mg/kg i.p.). Unlike fluoxetine, vilazodone-induced extracellular 5-HT output was not potentiated by cotreatment with the 5-HT1A receptor blocker N-[2-(4-{2-methoxyphenyl}-1-piperazinyl)-ethyl]-N-2-pyridinylcyclohexanecarboxamide (WAY 100635). In contrast to fluoxetine, vilazodone exhibited intrinsic 5-HT1A agonist activity: it reduced, similar to (+/-)-8-hydroxy-2-(dipropylamino)-tetralin (8-OH-DPAT), 5-HTP accumulation in striatum and n. raphe of reserpinized rats. Hence, vilazodone's agonistic actions must be 5-HT1A receptor-related since endogenous 5-HT is lacking in the reserpine-depleted animal. In spite of high intrinsic 5-HT1A activity in reserpinized rats, the net effect of vilazodone at release-regulating 5-HT1A autoreceptors must be inhibitory, leading to markedly increased 5-HT output. Another possibility is that vilazodone rapidly desensitizes autoinhibitory 5-HT1A receptors by an unknown mechanism.

Vilazodone has not been systematically evaluated in patients with seizure disorders; such patients were excluded from clinical studies. As with other antidepressants, vilazodone should be used with caution in patients with a history of seizure disorder

/SRP:/ Immediate first aid: Ensure that adequate decontamination has been carried out. If patient is not breathing, start artificial respiration, preferably with a demand valve resuscitator, bag-valve-mask device, or pocket mask, as trained. Perform CPR if necessary. Immediately flush contaminated eyes with gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient forward or place on the left side (head-down position, if possible) to maintain an open airway and prevent aspiration. Keep patient quiet and maintain normal body temperature. Obtain medical attention. /Poisons A and B/

/SRP:/ Basic treatment: Establish a patent airway (oropharyngeal or nasopharyngeal airway, if needed). Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if needed. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if necessary ... . Monitor for shock and treat if necessary ... . Anticipate seizures and treat if necessary ... . For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with 0.9% saline (NS) during transport ... . Do not use emetics. For ingestion, rinse mouth and administer 5 mL/kg up to 200 mL of water for dilution if the patient can swallow, has a strong gag reflex, and does not drool ... . Cover skin burns with dry sterile dressings after decontamination ... . /Poisons A and B/

/SRP:/ Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in severe respiratory distress. Positive-pressure ventilation techniques with a bag valve mask device may be beneficial. Consider drug therapy for pulmonary edema ... . Consider administering a beta agonist such as albuterol for severe bronchospasm ... . Monitor cardiac rhythm and treat arrhythmias as necessary ... . Start IV administration of D5W TKO /SRP: "To keep open", minimal flow rate/. Use 0.9% saline (NS) or lactated Ringer's (LR) if signs of hypovolemia are present. For hypotension with signs of hypovolemia, administer fluid cautiously. Watch for signs of fluid overload ... . Treat seizures with diazepam or lorazepam ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Poisons A and B/

No specific antidotes for vilazodone are known. In case of an overdose, provide supportive care, including close medical supervision and monitoring. Treatment should consist of those general measures employed in the management of overdosage with any drug. Consider the possibility of multiple drug overdose. Ensure an adequate airway, oxygenation, and ventilation. Monitor cardiac rhythm and vital signs. General supportive and symptomatic measures are also recommended. ... Removal of vilazodone by dialysis has not been studied; however, the high volume of distribution of vilazodone suggests that dialysis will not be effective in reducing vilazodone plasma concentrations.

For more Antidote and Emergency Treatment (Complete) data for Vilazodone (8 total), please visit the HSDB record page.

◉ Summary of Use during Lactation

◈ What is vilazodone?

The Approved Drug Products with Therapeutic Equivalence Evaluations identifies currently marketed prescription drug products, including vilazodone hydrochloride, approved on the basis of safety and effectiveness by FDA under sections 505 of the Federal Food, Drug, and Cosmetic Act. /Vilazodone hydrochloride/

N - Nervous system

QN - Nervous system

Vilazodone increases serotonin levels in the brain by inhibiting the reuptake of serotonin while acting as a partial agonist on serotonin-1A receptors. Due to this activity vilazodone has sometimes been referred to as a selective partial agonist and reuptake inhibitor (SPARI).

Vilazodone selectively inhibits serotonin reuptake in the central nervous system as well as acting as a partial agonist of 5HT-1A receptors. The exact mechanism for how these effects translate to its antidepressant effects are not known, though there is an association between these effects and antidepressive activity.

Vilazodone has been reported to be an inhibitor of 5-hydoxytryptamine (5-HT) reuptake and a partial agonist at 5-HT1A receptors. Using [35S]GTPgammaS binding in rat hippocampal tissue, vilazodone was demonstrated to have an intrinsic activity comparable to the 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT). Vilazodone (1-10 mg/kg p.o.) dose-dependently displaced in vivo [3H]DASB (N,N-dimethyl-2-(2-amino-4-cyanophenylthio)benzylamine) binding from rat cortex and hippocampus, indicating that vilazodone occupies 5-HT transporters in vivo. Using in vivo microdialysis, vilazodone (10 mg/kg p.o.) was demonstrated to cause a 2-fold increase in extracellular 5-HT but no change in noradrenaline or dopamine levels in frontal cortex of freely moving rats. In contrast, administration of 8-OH-DPAT (0.3 mg/kg s.c.), either alone or in combination with a serotonin specific reuptake inhibitor (SSRI; paroxetine, 3 mg/kg p.o.), produced no increase in cortical 5-HT whilst increasing noradrenaline and dopamine 2 and 4 fold, respectively. A 2-fold increase in extracellular 5-HT levels (but no change in noradrenaline or dopamine levels) was observed after combination of the 5-HT(1A) receptor antagonist, N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(pyridinyl)cyclohexanecarboxamide) (WAY-100635; 0.3 mg/kg s.c.) and paroxetine (3 mg/kg p.o.). In summary, vilazodone behaved as a high efficacy partial agonist at the rat hippocampal 5-HT1A receptors in vitro and occupied 5-HT transporters in vivo. In vivo vilazodone induced a selective increase in extracellular levels of 5-HT in the rat frontal cortex. This profile was similar to that seen with a 5-HT1A receptor antagonist plus an SSRI but in contrast to 8-OH-DPAT either alone or in combination with paroxetine.

The mechanism of the antidepressant effect of vilazodone is not fully understood but is thought to be related to its enhancement of serotonergic activity in the CNS through selective inhibition of serotonin reuptake. Vilazodone is also a partial agonist at serotonergic 5-HT1A receptors; however, the net result of this action on serotonergic transmission and its role in vilazodone's antidepressant effect are unknown.

The recently approved antidepressant vilazodone, a serotonin (5-HT)1A receptor partial agonist/selective 5-HT reuptake inhibitor offers new possibilities to study the underlying mechanisms of depression pharmacotherapy and of 5-HT augmenting antidepressants. ... 5-HT levels /were measured/ in two subregions of the rat prefrontal cortex by microdialysis, and 5-hydroxytryptophan (5-HTP) accumulation and tissue 5-HT concentrations ex vivo. Vilazodone-induced maximal 5-HT levels were similar in the medial and the lateral cortex and were up to sixfold higher than those induced by paroxetine, citalopram, or fluoxetine tested in parallel. Depolarization/autoreceptor-insensitive 5-HT release by vilazodone could be excluded. The citalopram (1 uM, locally infused)-induced increase of 5-HT was further increased by vilazodone (1 mg/kg i.p.), but not by citalopram (10 mg/kg i.p.). Unlike fluoxetine, vilazodone-induced extracellular 5-HT output was not potentiated by cotreatment with the 5-HT1A receptor blocker N-[2-(4-{2-methoxyphenyl}-1-piperazinyl)-ethyl]-N-2-pyridinylcyclohexanecarboxamide (WAY 100635). In contrast to fluoxetine, vilazodone exhibited intrinsic 5-HT1A agonist activity: it reduced, similar to (+/-)-8-hydroxy-2-(dipropylamino)-tetralin (8-OH-DPAT), 5-HTP accumulation in striatum and n. raphe of reserpinized rats. Hence, vilazodone's agonistic actions must be 5-HT1A receptor-related since endogenous 5-HT is lacking in the reserpine-depleted animal. In spite of high intrinsic 5-HT1A activity in reserpinized rats, the net effect of vilazodone at release-regulating 5-HT1A autoreceptors must be inhibitory, leading to markedly increased 5-HT output. Another possibility is that vilazodone rapidly desensitizes autoinhibitory 5-HT1A receptors by an unknown mechanism.

This study examined the effect of vilazodone, a combined serotonin (5-HT) reuptake inhibitor and 5-HT(1A) receptor partial agonist, paroxetine and fluoxetine on the sensitivity of 5-HT(1A) autoreceptors of serotonergic dorsal raphe nucleus neurons in rats. These effects were assessed by determining the intravenous dose of (+/-)-8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT) required to suppress the basal firing rate of these neurons by 50% (ID50) in anesthetized rats using in vivo electrophysiology. 5-HT uptake inhibition was determined by the ability of the compounds to reverse (+/-)-p-chloroamphetamine (PCA)-induced rat hypothalamic 5-HT depletion ex vivo. Acute vilazodone administration (0.63 and 2.1 umol/kg, s.c.), compared with vehicle, significantly increased (2-3-fold) the ID50 of 8-OH-DPAT at 4 hr, but not 24 hr after administration. Subchronic administration (3 days) significantly increased the ID50 value at 4 hr (3-4-fold) and at 24 hr (approximately 2-fold). In contrast, paroxetine and fluoxetine at doses that were supramaximal for 5-HT uptake inhibition did not significantly alter the ID50 value of 8-OH-DPAT after acute or subchronic administration. Vilazodone antagonized the action of PCA 3.5 hr and 5 hr after a single dose (ID50 1.49 and 0.46 umol/kg, s.c., respectively), but was inactive 18 hr post-administration, corroborating the electrophysiological results at 24 hr following acute administration. The results are consistent with the concept of rapid and, following repeated treatment, prolonged inhibition of 5-HT(1A) autoreceptors by vilazodone. This effect could occur by either direct interaction with, or desensitization of, these receptors, an effect which cannot be ascribed to vilazodone's 5-HT reuptake inhibiting properties.

25 hours. Other studies show a half life of 24±5.2h with a single 40mg dose and 28.9±3.2h with repeated doses.

Vilazodone /has/ a terminal half-life of approximately 25 hours.

Vilazodone is mainly metabolized by cytochrome P450(CYP)3A4 and also to a minor extent by CYP2C19 and CYP 2D6. Although the metabolic pathway for vilazodone has not been fully studied, a proposed mechanism for metabolism in rats was published in 2017.

Viibryd is extensively metabolized through CYP and non-CYP pathways (possibly by carboxylesterase), with only 1% of the dose recovered in the urine and 2% of the dose recovered in the feces as unchanged vilazodone. CYP3A4 is primarily responsible for its metabolism among CYP pathways, with minor contributions from CYP2C19 and CYP2D6. In vitro studies with human microsomes and human hepatocytes indicate that vilazodone is unlikely to inhibit or induce the metabolism of other CYP (except for CYP2C8) substrates; and an in vivo study with probe substrates for CYP2C19, 2D6 and 3A4 showed vilazodone did not alter the pharmacokinetics of the probe substrates. However, an in vivo study with probe substrate for CYP2C19 demonstrated a minor induction of CYP2C19. Strong inhibitors of CYP3A4 (e.g., ketoconazole) can reduce the metabolism of vilazodone in vivo and increase exposure. Conversely, strong inducers of CYP3A4 (e.g., carbamazepine) can decrease vilazodone exposure.

Mood-stimulating drugs used primarily in the treatment of affective disorders and related conditions. Several MONOAMINE OXIDASE INHIBITORS are useful as antidepressants apparently as a long-term consequence of their modulation of catecholamine levels. The tricyclic compounds useful as antidepressive agents (ANTIDEPRESSIVE AGENTS, TRICYCLIC) also appear to act through brain catecholamine systems. A third group (ANTIDEPRESSIVE AGENTS, SECOND-GENERATION) is a diverse group of drugs including some that act specifically on serotonergic systems.

Endogenous compounds and drugs that specifically stimulate SEROTONIN 5-HT1 RECEPTORS. Included under this heading are agonists for one or more of the specific 5-HT1 receptor subtypes.

Compounds that specifically inhibit the reuptake of serotonin in the brain.

Vilazodone's bioavailability is 72% when taken with food.

1% of the dose is recovered unchanged in the urine and 2% of the dose is recovered unchanged in the feces.

Vilazodone's volume of distribution is unknown but large

Clearance of vilazodone is 19.9-25.1L/h in patients with mild to moderate renal impairment compared to 26.4-26.9L/h in healthy controls.

Vilazodone concentrations peak at a median of 4-5 hours (Tmax) after administration and decline with a terminal half-life of approximately 25 hours. The absolute bioavailability of vilazodone is 72% with food. Administration of VIIBRYD with food (high fat or light meal) increases oral bioavailability (Cmax increased by approximately 147-160%, and AUC increased by approximately 64-85%).

Vilazodone is widely distributed and approximately 96-99% protein-bound.

Antidepressant

MEDICATION

Preparation: H. Bottcher et al., German patent 4333254; eidem, United States of America patent 5532241 (1995, 1996 both to Merck Patent GmbH).

From hydrochloride-saturated 2-propanol /Vilazodone hydrochloride/