Addressing Involuntary Movements in Tardive Dyskinesia

Inclusion Criteria: * History of using a dopamine receptor antagonist for at least 3 months * Clinical diagnosis of tardive dyskinesia and has had symptoms for at least 3 months prior to screening * Subjects with underlying psychiatric diagnosis are stable and have no change in psychoactive medications * Have a mental health provider and does not anticipate any changes to treatment regimen in the next 3 months * History of being compliant with prescribed medications * Able to swallow study drug whole * Be in good general health and is expected to attend all study visits and complete study assessments * Female subjects must not be pregnant and must agree to an acceptable method of contraception throughout the study Exclusion Criteria: * Currently receiving medication for the treatment of tardive dyskinesia * Have a neurological condition other than tardive dyskinesia that may interfere with assessing the severity of dyskinesias * Have a serious untreated or undertreated psychiatric illness * Have recent history or presence of violent behavior * Have unstable or serious medical illness * Have evidence of hepatic impairment * Have evidence of renal impairment * Have known allergy to any component of SD-809 or tetrabenazine * Has participated in an investigational drug or device trial and received study drug or device within 30 days * Have acknowledged use of illicit drugs * Have a history of alcohol or substance abuse in the previous 12 months