D.C.-based biotech company Vanda Pharmaceuticals saw its stock jump after a drug was approved by the Food and Drug Administration to be used as a treatment for bipolar disorder.

Fanapt, developed by Vanda, was previously FDA-approved in 2009 for the treatment of schizophrenia.

It is now approved for the treatment of manic or mixed episodes associated with bipolar I disorder in adults — a disorder that affects approximately 2.8% of the U.S. adult population, according to a 2007 Harvard Medical School survey.

At 83%, a majority of the cases are classified as severe, according to the survey.

FDA approval followed a 400-patient study measuring treatment outcomes over a four-week period.

Fanapt is one of two commercially-approved drugs for Vanda Pharmaceuticals. The other, Hetlioz, is used to treat sleeping disorders.

The company has a number of experimental drugs in its pipeline, including those for treatments of jet lag, sea sickness and stage fright.

As of 10 a.m. Wednesday, Vanda stock was up $2.06 to $5.97 per share, a gain of 53%.