This pilot study is to research whether or not the investigational drug clavulanic acid, along with medication management, can help people with cocaine use disorder who are interested in quitting. Participants who are eligible after screening visits are randomly assigned to take clavulanic acid or placebo for twelve weeks and will meet with study staff three times a week for urine drug screens.

This research study will include heavy, long-term cannabis users with moderate to severe use desire who want or need to discontinue cannabis use and have previously had symptoms of cannabis withdrawal. Subjects participating in this research study will receive either PP-01 higher dose or lower dose (combination of nabilone and gabapentin in a varied amount), nabilone only, gabapentin only or placebo (inactive substance). This study will assess whether the study drugs help to lessen or alleviate cannabis withdrawal symptoms in study subjects.

After initial eligibility screening, Veterans who use both cannabis and tobacco will be randomly assigned to receive either varenicline (Chantix) or placebo for 12 weeks. Participants will attend weekly visits to provide breath and urine samples for testing, fill out questionnaires, and meet with study staff about medication compliance.

Marijuana is the most commonly used illicit drug. There is high demand for effective interventions for cannabis use disorder, yet few specific treatments for have been developed. This study will evaluate the efficacy of varenicline for reducing marijuana use in people who use marijuana frequently.

The purpose of the study is to determine if the hormone progesterone affects marijuana users' stress response and marijuana use. Participation lasts approximately three weeks. During the first week, participants are randomly assigned to take either progesterone or placebo and remain abstinent from marijuana. They return at the end of the week to participate in a stress task. Throughout the three weeks, participants complete "CREMA" sessions (Cue Reactivity Ecologic Momentary Assessment) three times a day. These sessions include looking at stressful and neutral pictures and rating stress and craving.

This study will examine whether the investigational medication PF-0447845 is safe and effective in reducing cannabis use among people who frequently use cannabis. This is a 14-week, randomized, double-blind, placebo-controlled outpatient clinical trial that will be conducted at 4 research sites in the eastern U.S.