Dec 16 (Reuters) - Auspex Pharmaceuticals Inc said its drug for treating chorea, or involuntary movement associated with Huntington's disease, met the main goal in a late-stage study.

The drug, SD-809, achieved the main goal of change in a standardized score that measures involuntary movement in patients, compared with a placebo.

About 90 percent of patients with Huntington's disease develop chorea, characterized by involuntary, excessive movements that can impact all parts of the body and interfere with motor functions.

The company plans to apply for the drug's regulatory approval by mid-2015.

(Reporting by Amrutha Penumudi in Bengaluru; Editing by Joyjeet Das)