The aim of this study is to assess the efficacy of caffeine compared to placebo as a maintenance treatment for cocaine dependence. Caffeine potentiation with biperiden will be also studied.

Ninety patients with snorted/sniffed cocaine dependence will be randomized to receive caffeine (300 - 1200 mg t.i.d.) plus biperidene (8 mg b.i.d.) caffeine (300 - 1200 mg t.i.d.) with placebo or placebo during 10 days in an in-hospital setting.

Inclusion Criteria:

• diagnosis of cocaine dependence, according to DSM-IV-TR criteria
• age between 18 and 60 years
• current cocaine use, confirmed by a positive urine drug screen for cocaine the week prior to admission.
• demonstrated capacity to grant informed consent and sign the pertinent informed consent form.
• place of residence compatible with attendance at the center.
• for women, willingness to use effective contraceptive measures during the study.

Exclusion Criteria:

• diagnosis of a severe medical disorder that could interfere with the study
• presence of an organic pathology for which methylxanthines or biperidene administration is contraindicated
• serum liver transaminase levels 3 times higher than normal values
• pregnancy and breast-feeding
• neuroleptic medication treatment in the past 6 weeks
• current treatment, or anticipation that the patient may need to initiate treatment during the study, with drugs that may interact with study medication.
• current diagnosis of a major mental disorder.
• awareness of a situation that could prevent the patient's participation in the study (e.g. serving a sentence)
• current participation in another research project.