Hormones and Reduction in Co-users of Marijuana and Nicotine

This double-blind, randomized pilot clinical trial will prescreen an estimated 250 potential subjects, consent and further evaluate approximately 100 potential subjects, and ultimately enroll 70 subjects to ensure 40 subjects will provide a primary marijuana reduction outcome measure at four weeks post quit date. Subjects will be stratified by sex then randomized to one of two treatment groups (n=20 per drug group, 50% female): progesterone (PRO; 200mg 2x/day) or Placebo (PBO). Telephone screening and visit invitation (20 minutes) leads to the consent process and in-person screening including medical-psychiatric evaluation for inclusion/exclusion (two visits, two hours each), then randomization and medication start (7 days), then stable medication (28 days) with medication reduction and final evaluation (7 days).