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.