Carbidopa/Levodopa Combined With Behavioral Therapy for the Treatment of Cocaine Dependence
Condition: Cocaine Dependence
MeSH terms: Cocaine-Related Disorders
Intervention: levodopa; Placebo; Cognitive Behavioral Therapy; Contingency Management
Intervention description: 800mg levodopa and 200mg carbidopa per day; Placebo; Participants received individual cognitive behavioral therapy (CBT) in 50-minute weekly sessions. These sessions were manual-driven and based on the relapse prevention model proposed by Marlatt and Gordon (1985). Trained masters-level therapists, under the supervision of senior therapists and the principal investigator, worked with participants to teach them how to recognize and cope with risky situations that could influence their cocaine use through self-monitoring of situational craving and drug use stimuli, coping skills training, and lifestyle modifications.; An abstinence-based contingency management (CM) procedure was used. Participants earned vouchers according to the reward schedule recommended by Budney and Higgins (1998), beginning at $2.50 for the first cocaine-negative urine. For each consecutive cocaine-negative urine, voucher values increased by $1.25 with a $10 bonus given for provision of three consecutive cocaine-negative urines within a week. A cocaine-positive urine or failure to provide a scheduled urine sample resulted in a reset of the schedule to the initial value of $2.50. After provision of five negative urines, the voucher returned to the value prior to the reset. Participants were able to redeem their vouchers for small amounts of cash (≤$25) or gift cards for goods and services.
Intervention MeSH terms: Levodopa
Phase: Phase 2
Study type: Interventional
Primary purpose: Treatment
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Enrollment: 85.0
Sex: All
Minimum age: 18 Years
Maximum age: 60 Years
Healthy volunteers: No
Keywords: Cocaine, levodopa, contingency management

Summary:

      Cocaine dependence is a major public health problem and the development of a treatment for
      this disorder is a priority. To date, treatment interventions based on positive incentive
      principles have shown the strongest effects for improving substance use outcomes. One such
      example is contingency management (CM) interventions in which nondrug rewards are used to
      compete with cocaine. Recent evidence suggests that certain medications improve response to
      CM interventions, particularly agents that target dopamine reward systems in the brain. A
      promising dopamine-enhancing medication is levodopa. The study team has observed the
      strongest effects of levodopa when the medication is administered in the context of CM
      therapy, perhaps through mechanisms that enhance reward saliency. The proposed study is
      designed to further evaluate this promising treatment approach. Cocaine dependent outpatients
      will participate in a randomized, 2-group (levodopa vs. placebo), double-blind clinical
      trial. CM will be behavioral therapy platform for both treatment groups. The study will test
      the primary hypothesis that CM+levodopa will be more effective than CM+placebo in reducing
      cocaine use. This study is expected to validate the usefulness of a new
      behavioral-pharmacological treatment approach for cocaine dependence.
    

Eligibility criteria:

        Inclusion Criteria:

          -  between 18 and 60 years of age

          -  meet Diagnostic and Statistical Manual of Mental Disorders, 4th. Edition (DSM-IV)
             criteria for current cocaine dependence.

          -  be in acceptable health on the basis of interview, medical history and physical exam.

        Exclusion Criteria:

          -  current DSM-IV diagnosis of any psychoactive substance dependence other than cocaine,
             marijuana, or nicotine.

          -  have a DSM-IV axis I psychiatric disorder or neurological disease or disorder
             requiring ongoing treatment and/or making study participation unsafe.

          -  have significant current suicidal or homicidal ideation.

          -  have medical conditions contraindicating levodopa/carbidopa pharmacotherapy.
             Conditions include severe pulmonary disease (bronchial asthma, emphysema),
             cardiovascular disease (severe or history of myocardial infarction with residual
             arrhythmias), narrow angle glaucoma, melanoma, history of peptic ulcer, renal function
             impairment.

          -  taking medications known to have significant drug interactions with levodopa/carbidopa
             (e.g., monoamine oxidase (MAO) inhibitors, anticonvulsants, haloperidol,
             phenothiazines, selegiline, anesthetics).

          -  currently or recently (last 3 months) treated for substance use or another psychiatric
             condition.

          -  having conditions of probation or parole requiring reports of drug use to officers of
             the court.

          -  impending incarceration.

          -  pregnant or nursing for female patients.

          -  inability to read, write, or speak English.