"Only orally given THC and, to a lesser extent, nefazodone have shown promise [in treating marijuana dependence]. THC reduced craving and ratings of anxiety, feelings of misery, difficulty sleeping, and chills (Haney et al., 2004). In addition, participants could not distinguish active THC from placebo. These findings were replicated in an outpatient study, which found that a moderate oral dosage of THC (10 mg, three times daily) suppressed many marijuana withdrawal symptoms and that a higher dosage (30 mg, three times daily) almost completely abolished withdrawal symptoms (Budney et al., 2007)."
Budney, Alan J.; Roffman, Roger; Stephens, Robert S.; Walker, Denise, "Marijuana Dependence and Its Treatment," Addiction Science & Clinical Practice, Rockville, MD: National Institute on Drug Abuse, December 2007.