This study will determine the safety, tolerability, and pharmacokinetics (PK) of olanzapine and samidorphan in adults with schizophrenia following 14 consecutive days of oral administration of ALKS 3831.

Inclusion Criteria:

• Has a body mass index (BMI) of 18.0-35.0 kg/m^2, inclusive
• Has a primary diagnosis of schizophrenia
• Capable of understanding and complying with the procedures, requirements, and restrictions of the protocol.
• Appropriate for outpatient treatment
• Agrees to abide by the contraception requirements specified in the protocol for the duration of the study or is surgically sterile
• Willing and able to provide government-issued identification
• Is in good physical health
• Agrees to maintain normal tobacco use as well as normal activities/exercise throughout the study
• Additional criteria may apply

Exclusion Criteria:

• Is currently pregnant or breastfeeding
• Initiated first antipsychotic treatment within the past 12 months, or <1 year has elapsed since the initial onset of active-phase schizophrenia symptoms
• Poses a current suicide risk at Visits 1 or 2
• Has a history of poor or inadequate response to treatment with olanzapine
• Has used a long-acting injectable antipsychotic medication in the last 6 months with the exception of 3-month paliperidone, which must not have been received within the past 12 months.
• Requires or has had electroconvulsive therapy (ECT) treatment in the 6-month period prior to Visit 1
• Has a diagnosis of alcohol or drug use disorder (with the exception of nicotine)
• Has taken opioid agonists (codeine, oxycodone, tramadol, or morphine) within the 14 days prior to Visit 1 and/or anticipates a need to take opioid medication during the study period.
• Has taken opioid antagonists including naltrexone (any formulations) and naloxone within 60 days prior to Visit 1, or has used any extended-release formulation of an opioid antagonist within 2 months prior to screening
• Tests positive for amphetamines/methamphetamine, cocaine, barbiturates, opioids (codeine, hydrocodone, hydromorphone, methadone, morphine, oxycodone, oxymorphone, and buprenorphine), phencyclidine and benzodiazepines.
• Has a known or suspected intolerance, allergy or hypersensitivity to olanzapine or opioid antagonists.
• Additional criteria may apply