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.