Multi-System Analysis of Opioid Receptor Binding

Investigational radiotracer to be injected by IV as s a bolus during both study PET/CT scans.

Non-selective opioid antagonist injected by IV parenterally during the second study PET/CT scan only.

Loperamide is an FDA- approved, over-the-counter drug for the control and symptomatic relief of acute or chronic diarrhea given orally prior to the optional HC third PET/CT scan only.