Valbenazine has been approved by the US Food and Drug Administration (FDA) to treat adults with tardive dyskinesia (TD), an involuntary movement disorder caused by long-term or high dosage of antipsychotic drugs.

The pharmaceutical company, Neurocrine Biosciences, based in San Diego, California, beat the rival Teva Pharmaceuticals in the race to win the first FDA approval of its oral vesicular monoamine transporter 2 (VMAT2) inhibitor, also known as valbenazine.

“Tardive dyskinesia can be disabling and can further stigmatise patients with mental illness,” said Mitchell Mathis, director of the Division of Psychiatry Products in the FDA’s Centre for Drug Evaluation and Research.

“Approving the first drug for the treatment of tardive dyskinesia is an important advance for patients suffering with this condition.”

TD a side effect from antipsychotic drugs

TD is associated with the usage of antipsychotic medications, particularly from older medications. About 5% to 8% of the patients who were treated long-term or high dose for antipsychotic drugs resulted in development of the disorder. It is a severe side effect, which leads to uncontrollable and uncoordinated body movements.

In addition to psychiatric disorders, patients who develop TD may become socially isolated with a higher tendency of developing dysmorphophobia, and may even lead to suicide. Besides, emotional or physical stress may easily worsen the dyskinetic movements.

“Until now, one of the few options for physicians, when managing TD, was to stop, change, or lower the dose of antipsychotic medication, potentially jeopardising patients' psychiatric stability,” said Christoph U Correll, professor of psychiatry and molecular medicine at Hofstra Northwell School of Medicine.

The drug, which inhibits VMAT2 and reduces the amount of dopamine released in the brain, will now be a viable option for patients already suffering from mental illness to manage their symptoms of TD.

“A treatment for tardive dyskinesia is a welcome and exciting step in the continued effort to destigmatise mental health conditions,” said Paul Gionfriddo, president and CEO of Mental Health America.

“With an FDA approved treatment now available, individuals and doctors can have more productive and proactive conversations about TD.”

Phase III clinical trial showed 50% reduction in symptoms

The phase III trial of the VMAT 2 inhibitor conducted by Neurocrine compared once-daily valbenazine 80mg and 40mg to placebo over six weeks by involving 234 patients with underlying schizophrenia, schizoaffective disorder or mood disorders. According to the results, a total of 40% of participants who received valbenazine achieved at least a 50% reduction in the Abnormal Involuntary Movement Scale (AIMS) dyskinesia total score, compared with 8.7% of placebo patients.

The clinical trial has also showed rapid and continuous improvement in TD symptoms throughout the 48 weeks of treatment, indicating a tremendous breakthrough for therapeutic application. Furthermore, the only adverse side effects that had affected more than 5% of patients taking the treatment were drowsiness and dry mouth.

The drug may result in sleepiness and QT prolongation. Therefore, patients with congenital long QT syndrome or with abnormal heartbeats associated with a prolonged QT interval are advised not to use valbenazine. Patients who receive valbenazine for treatment are also discouraged from driving or operating heavy machinery or carry out any high risk activities before the effects of the drug is known.

As valbenazine will be in the distribution channel soon, the newly approved drug for TD is expected to be introduced to healthcare professionals from May onwards. MIMS

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