Evaluation of Tirzepatide as an Adjunct to Buprenorphine for the Treatment of Opioid Use Disorder

The primary objective of this research study is to evaluate the effect of tirzepatide, relative to placebo, as an adjunct to BUP on retention, substance use, and sleep outcomes in individuals with OUD.

Inclusion Criteria: 1. Must be ≥18 years of age; 2. Must have moderate to severe OUD; 3. Must, at the time of randomization, be newly initiated on BUP (i.e., within 7 to 80 days) during the current treatment episode, be taking ≥ 8 mg/day of generic buprenorphine-naloxone film/tablets (or the equivalent for other buprenorphine products), have documentation of receiving BUP, including dose and the start date of the current treatment episode, from their BUP provider, and, for participants prescribed transmucosal BUP, have at least one UDS positive for buprenorphine/norbuprenorphine; 4. Must be willing to be randomized to tirzepatide or placebo and to comply with study procedures, including weekly visits for 6 months; 5. Must be able to understand the study, and having understood, provide written informed consent in English; 6. Must not be breastfeeding; if of child bearing potential, must test negative on the study-administered pregnancy test(s), and if of childbearing potential and engaging /planning to engage in sexual intercourse must agree to effective contraception for the duration of the trial through 30 days after the trial; effective contraception is defined as using: a) birth control injection, an intrauterine device, or implant; or b) two birth control methods - for example birth control pills with a barrier method (e.g., condoms, etc.). * If ever of childbearing potential, a participant is considered to not be of childbearing potential for the study if they are: 1. infertile due to surgical sterilization (hysterectomy, bilateral oophorectomy, tubal implants, or tubal ligation), congenital anomaly such as Mullerian agenesis; are 2. post-menopausal defined as ≥ 55 years old not on hormone therapy, who has had at least 12 months of spontaneous amenorrhea; 3. ≥ 55 years old with a diagnosis of menopause prior to starting hormone replacement therapy; or 4. ≥ 40 years old with an intact uterus, not on hormone therapy, who has cessation of menses for at least 1 year without an alternative medical cause, AND a follicle-stimulating hormone ≥ 40 mIU/mL; participants in this category must test negative on the study-administered pregnancy test(s). Exclusion Criteria: 1. have a history of type 1 or type 2 diabetes mellitus (other than pregnancy-related diabetes); 2. have a BMI \