The purpose of this research study is to: test the safety, tolerability, and pharmacokinetics (PK testing, the study of how the body absorbs, distributes, breaks down and eliminates a drug) of a single dose of the investigational study drug NBI-98854 in subjects with normal hepatic function or mild, moderate, or severe hepatic impairment.

Inclusion Criteria:

• Male or female, 18 to 75 years of age.
• Healthy volunteers must be in good general health.
• Subjects with hepatic impairment must be judged to be in stable condition.
• Subjects of childbearing potential must agree to use hormonal or two forms of nonhormonal birth control during the study.
• Female subjects must not be pregnant, given birth within 1 year of study start, or breastfeeding.
• Have a body mass index (BMI) of 18 to 40 kg/m2 (both inclusive).

Exclusion Criteria:

• Report more than two alcoholic beverages daily or more than 14 alcoholic beverages weekly withing 7 days of study start.
• Have a known history of neuroleptic malignant syndrome.
• Have a positive human immunodeficiency virus (HIV) antibody result at screening or have a history of positive result.
• Have received an investigational drug within 30 days before screening or plan to use an investigational drug (other than NBI-98854) during the study.
• Have an allergy, hypersensitivity, or intolerance to tetrabenazine.
• Had a blood loss greater than or equal to 500 mL or donated blood within 56 days of study start.
• Have had previous exposure with NBI-98854.