Neurocrine Biosciences’ Ingrezza has become the first drug approved to treat the hyperkinetic movement disorder tardive dyskinesia in the US.

Tardive dyskinesia is characterised by repetitive involuntary movements, usually of the jaw, lips and tongue, such as grimacing, sticking out the tongue and smacking the lips, and some patients also experience involuntary movement of the extremities or difficulty breathing.

The condition is a serious side effect sometimes seen in patients who have been treated with antipsychotics for long periods to treat chronic conditions such as schizophrenia and bipolar disorder, and can also occur in patients taking such medicines for depression as well as certain other medications for gastrointestinal disorders and other illnesses.

Ingrezza (valbenazine) is a novel, selective vesicular monoamine transporter 2 (VMAT2) inhibitor, shown in clinical trials to significantly improve the severity of abnormal involuntary movements compared to placebo without compromising underlying psychiatric care.

"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," noted Christoph U. Correll, Professor, Psychiatry and Molecular Medicine, Hofstra Northwell School of Medicine, adding that the drug represented “a tremendous breakthrough for patients”.

On the safety side, Ingrezza was generally well tolerated, with somnolence as the only adverse event occurring at a rate greater than or equal to 5 percent and twice placebo. But the drug may cause serious side effects including sleepiness and heart rhythm problems. As such, the US Food and Drug Administration has stipulated that its use should be avoided in patients with congenital long QT syndrome or with abnormal heartbeats associated with a prolonged QT interval.

"The often debilitating effects of tardive dyskinesia have left people feeling isolated and forgotten. The approval of Ingrezza represents a turning point for these patients and their care partners, offering a meaningful treatment where before there was little hope," said Kevin C. Gorman, Neurocrine’s chief executive.

Analysts believe the drug could eventually pull in peak sales of $1 billion.