New combo tackles meth cravings on demand

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

Inclusion Criteria: * cisgender male (male gender and sex assigned at birth) * age 18-70 years\* (naltrexone's tolerability and safety has been demonstrated among older adults up to age 70) * self-reported condomless anal sex with men or missing Pre-Exposure Prophylaxis or antiretroviral therapy doses due to meth use in the prior three months while under the influence of meth * self-reported meth use at least weekly * mild, moderate or severe meth use disorder * positive meth sample via sweat patch or urine testing during screening * interested in reducing meth use * no current acute illness requiring prolonged medical care * no chronic illness that is likely to progress clinically during trial * able and willing to provide informed consent and adhere to visit schedule * current CD4 count ≥ 200 cells/mm3; or CD4 count of 100-199 cells/mm3 and HIV viral load \< 200 copies/mL (if living with HIV) * baseline complete blood count, total protein, albumin, glucose, alkaline phosphatase, creatinine, blood urea nitrogen test, and electrolytes without clinically significant abnormalities as determined by study clinician in conjunction with symptoms, physical exam, and medical history Exclusion Criteria: * any psychiatric (e.g., depression with suicidal ideation) or medical condition that would preclude safe participation * known allergy or prior adverse reaction to naltrexone * current use of any opioids or a known medical condition which currently requires or may likely require opioid analgesics * opioid-positive urine test at screen/enrollment visits (naltrexone can induce opioid withdrawal) * moderate or severe liver disease (aspartate aminotransferase test, alanine aminotransferase test, or total bilirubin \> 3 times upper limit of normal) * impaired renal function (creatinine clearance \< 60 ml/min) * currently participating in another intervention research study with potential overlap * severe alcohol use disorder as determined by structured clinical interview for DSM-5 criteria * any condition that, in the PI and/or study clinician's judgment interferes with safe participation or adherence to study procedures