Effect of Olanzapine on Opioid Craving and Misuse Among Patients Receiving Opioids for Cancer-related Pain: A Pilot Double-Blind, Randomized Control Trial

To learn about the effectiveness of taking the antipsychotic medication olanzapine to help lower opioid craving.

Inclusion Criteria: 1. Age 18 years or older 2. Diagnosis of cancer pain 3. Receiving long-term opioid therapy (≥ 7 days)32 4. Active use of opioids within the past 7 days 5. Opioid misuse behavior (COMM score ≥ 9/68) 6. Seen by a Supportive Care Clinic or Pain Clinic clinician 7. ECOG performance status ≥ 2/4 8. Ability to communicate in English 9. Ability to understand and the willingness to sign a written informed consent document. Exclusion Criteria: 1. Contraindications to, or allergic to, olanzapine 2. Current use of any antipsychotic medication (e.g. quetiapine, haloperidol, risperidone, etc.) 3. History of OUD or other substance use disorders, except marijuana 4. History of formal psychiatric diagnoses (e.g. bipolar disorder, schizophrenia, major depressive disorder, or anorexia nervosa) 5. Hepatic insufficiency (defined as alanine aminotransferase (ALT) or aspartate aminotransferase (AST) \> 3 times the highest normal value, or total bilirubin \>1.5 times the highest normal value) within the past month 6. History of uncontrolled Diabetes Mellitus or hyperglycemia (fasting ≥ 200 mg/dL) within the past month 7. History of seizure disorder or neuroleptic malignant syndrome 8. History of cardiac disease (e.g. coronary artery disease, congestive heart failure) 9. (Females only) Known pregnancy, as communicated to study personnel by clinicians; females of childbearing potential will receive advice to use methods of contraception per usual care.