Forest Laboratories, Inc. announced that Viibryd (vilazodone HCl) tablets is now available at pharmacies throughout the United States. Viibryd is a prescription medicine indicated for the treatment of adults with Major Depressive Disorder (MDD).

The US Food and Drug Administration (FDA) approved Viibryd as a new molecular entity on January 21, 2011, making it the first and only approved Selective Serotonin Reuptake Inhibitor (SSRI) and 5HT1Areceptor partial agonist. The mechanism of the antidepressant effect of Viibryd is not fully understood but is thought to be related to its enhancement of serotonergic activity in the Central Nervous System (CNS) through selective inhibition of serotonin reuptake. Vilazodone is also a partial agonist at serotonergic 5HT1Areceptors; however, the net result of this action on serotonergic transmission and its role in vilazodone's antidepressant effect are unknown.

The efficacy of Viibryd as a treatment for MDD was established in two 8-week, multi-centre, randomized, double-blind, placebo-controlled studies of 861 adult patients, 436 of whom received Viibryd, and who met the criteria for MDD. In these studies, patients were titrated over two weeks to a dose of 40 mg of Viibryd once daily with food. Viibryd was superior to placebo in the improvement of depressive symptoms as measured by the mean change from baseline (95% confidence interval) to week 8 in the Montgomery-Asberg Depression Rating Scale (MADRS) total score of -3.2 (-5.2, -1.3) and -2.5 (-4.4, -0.6) for Studies 1 and 2, respectively.

Viibryd was demonstrated to be safe in clinical studies. In the placebo-controlled, pivotal studies, the most commonly observed adverse reactions in Viibryd-treated patients were diarrhoea, nausea, vomiting and insomnia. No single adverse event led to discontinuation of treatment in greater than 1% of patients. Overall, 7.1% of the patients who received Viibryd discontinued treatment due to an adverse reaction, compared with 3.2% of placebo-treated patients.

Viibryd has not been associated with any clinically important changes in laboratory test parameters including liver function tests, ECG including QT interval or vital signs. In addition, Viibryd had no effect on body weight as measured by mean change from baseline in the 8-week studies. Among the common adverse reactions (greater-than or equal to 2%) related to sexual function with Viibryd compared to placebo were decreased libido (4% vs <1%), abnormal orgasm (3% vs 0%), delayed ejaculation (2% vs 0%, males only) and erectile dysfunction (2% vs 1%, males only).

MDD is a serious medical condition requiring treatment, which affects more than 15 million adults in the United States yearly or approximately 6.5% of the adult US population. A person diagnosed with MDD exhibits a combination of symptoms that interfere with one's ability to work, sleep, study, eat, and enjoy once-pleasurable activities. Despite the seriousness of the condition, nearly 50 percent of people with MDD do not receive treatment.

Antidepressants increased the risk compared to placebo of suicidal thinking and behaviour (suicidality) in children, adolescents, and young adults in short-term studies of Major Depressive Disorder (MDD) and other psychiatric disorders. Anyone considering the use of Viibryd or any other antidepressant in a child, adolescent, or young adult must balance this risk with the clinical need. Short-term studies did not show an increase in the risk of suicidality with antidepressants compared to placebo in adults beyond age 24; there was a reduction in risk with antidepressants compared to placebo in adults aged 65 and older.

Depression and certain other psychiatric disorders are themselves associated with increases in the risk of suicide. Patients of all ages who are started on antidepressant therapy should be monitored appropriately and observed closely for clinical worsening, suicidality, or unusual changes in behaviour. Families and caregivers should be advised of the need for close observation and communication with the prescriber. Viibryd is not approved for use in paediatric patients.

Viibryd must not be used concomitantly in patients taking MAOIs or in patients who have taken MAOIs within the preceding 14 days due to the risk of serious, sometimes fatal, drug interactions with serotonergic drugs. Allow at least 14 days after stopping Viibryd before starting an MAOI.

All patients treated with antidepressants should be monitored appropriately and observed closely for clinical worsening, suicidality, and unusual changes in behaviour, especially during the first few months of treatment and when changing the dose. Consider changing the therapeutic regimen, including possibly discontinuing the medication, in patients whose depression is persistently worse or includes symptoms of anxiety, agitation, panic attacks, insomnia, irritability, hostility, aggressiveness, impulsivity, akathisia, hypomania, mania, or suicidality that are severe, abrupt in onset, or were not part of the patient's presenting symptoms.

Families and caregivers of patients being treated with antidepressants should be alerted about the need to monitor patients daily. Prescriptions for Viibryd should be written for the smallest quantity of tablets consistent with good patient management, in order to reduce the risk of overdose.

The development of potentially life-threatening serotonin syndrome or Neuroleptic Malignant Syndrome (NMS)-like reactions has been reported with antidepressants alone, but particularly with concomitant use of serotonergic drugs (including triptans) with drugs which impair metabolism of serotonin (including MAOIs), or with antipsychotics or other dopamine antagonists. Symptoms of serotonin syndrome were noted in 0.1% of patients treated with Viibryd.

Serotonin syndrome symptoms may include mental status changes (eg, agitation, hallucinations, coma), autonomic instability (eg, tachycardia, labile blood pressure, hyperthermia), neuromuscular aberrations (eg, hyperreflexia, incoordination) and/or gastrointestinal symptoms (eg, nausea, vomiting, diarrhea). Patients should be monitored for the emergence of serotonin syndrome or NMS-like signs and symptoms while treated with Viibryd.

Like other antidepressants, Viibryd should be prescribed with caution in patients with a seizure disorder. The use of drugs that interfere with serotonin reuptake, including Viibryd, may increase the risk of bleeding events. Patients should be cautioned about the risk of bleeding associated with the concomitant use of Viibryd and NSAIDs, aspirin, warfarin, or other drugs that affect coagulation or bleeding.

Symptoms of mania/hypomania were noted in 0.1% of patients treated with VIIBRYD in clinical studies. As with all antidepressants, Viibryd should be used cautiously in patients with a history or family history of bipolar disorder, mania or hypomania. Prior to initiating treatment with an antidepressant, patients with depressive symptoms should be adequately screened to determine if they are at risk for bipolar disorder. Viibryd is not approved for use in treating bipolar depression.

Discontinuation symptoms have been reported with discontinuation of serotonergic drugs such as Viibryd. Gradual dose reduction is recommended, instead of abrupt discontinuation, whenever possible. Monitor patients when discontinuing Viibryd. If intolerable symptoms occur following a dose decrease or upon discontinuation of treatment, consider resuming the previously prescribed dose and decreasing the dose at a more gradual rate.

Advise patients that if they are treated with diuretics, or are otherwise volume depleted, or are elderly, they may be at greater risk of developing hyponatremia while taking Viibryd. Although no cases of hyponatremia resulting from Viibryd treatment were reported in the clinical studies, hyponatremia has occurred as a result of treatment with SSRIs and SNRIs. Discontinuation of Viibryd in patients with symptomatic hyponatremia and appropriate medical intervention should be instituted.

The most commonly observed adverse reactions in MDD patients treated with Viibryd in placebo-controlled studies (incidence greater-than or equal to 5% and at least twice the rate of placebo) were: diarrhoea (28% vs 9%), nausea (23% vs 5%), insomnia (6% vs 2%), and vomiting (5% vs 1%).

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