New bipolar drug MK-8189 passes early safety check in small study

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: The main inclusion criteria include but are not limited to the following: * Meets diagnostic criteria for bipolar I disorder, manic or mixed features according to the Diagnostic and statistical manual of Mental Disorders TR (DSM-5 TR) and considered to be in a non-acute phase of their illness. * History of receiving and tolerating antipsychotic medication within the usual dose range employed for bipolar I disorder. * Body mass index is 18 and 40 kg/m\^2, inclusive. * If currently taking an antipsychotic, is able to discontinue use at least 5 days prior to study start and the duration of the study. Exclusion Criteria: The main exclusion criteria include but are not limited to the following: * Untreated or uncompensated endocrine, gastrointestinal, cardiovascular, hematological, hepatic, immunological, renal, respiratory, genitourinary, or major neurological abnormalities or diseases. * Evidence or history of a primary DSM-5 axis I psychiatric diagnosis other than those specified for inclusion. * History of cancer (malignancy). * Evidence or history of mental retardation, borderline personality disorder, or organic brain syndrome. * History of neuroleptic malignant syndrome or moderate to severe tardive dyskinesia. * Substance-induced psychotic disorder or behavioral disturbance. * DSM-5 TR defined substance use disorder within 3 months of screening. * History of seizure disorder beyond childhood or is receiving treatment with any anticonvulsant to prevent seizures. * Positive test(s) for hepatitis B surface antigen, hepatitis C antibodies or human immunodeficiency virus. * Major surgery or donation/loss of 1 unit of blood within 4 weeks prior to screening. * Received any vaccine starting from 30 days prior to study intervention or is scheduled to receive any vaccine through 30 days following study intervention.