Naltrexone as anti-craving medication in cannabis addicts

INTERVENTION: Naltrexone 50 mg/day or placebo will be administered for eight weeks. CONDITION: ; Cannabis ; ; PRIMARY OUTCOME: The initial assessment will entail the MATE‐scale to establish the social and general functioning, a short depression questionnaire to rule out a depressive disorder, a thorough assessment of current cannabis use and the use of other addictive substances, validated questionnaires for subjective craving for cannabis (e.g. Desires for Drug Questionnaire, Obsessive Compulsive Drug Use Scale; Franken et al., 2002), a visual analogue scale for craving for cannabis (VAS; Franken and Muris, 2005), a VAS for craving for other addictive substances, blood pressure and pulse, basic blood lab of liver function and extra blood will be frozen for possible later research on genetic markers.; ; At two, four, six and eight weeks the assessment will ential an assessment of the use of the medication, of cannabis use, of the use of other addictive substances, of side effects, a VAS of craving for cannabis and a VAS of craving for other addictive substances.; ; At eight weeks the MATE‐scale, blood pressure and pulse, and basic blood lab of liver function will also be measured. SECONDARY OUTCOME: If at the conclusion of the study there are clear distinct outcomes, we might use the extra blood for research on genetic markers. INCLUSION CRITERIA: 1. Male of female, age 18‐60 years; 2. Current DSM‐IV diagnosis of cannabis abuse or dependence; 3. Able to provide written informed consent and to comply with all study procedures.