Carbidopa/Levodopa Combined With Behavioral Therapy for the Treatment of Cocaine Dependence

Official Title: “Contingency Management Plus Levodopa/Carbidopa for Treatment of Cocaine Dependence”

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. We have 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. Potential treatment predictors related to reward saliency and motivation will be assessed before and during treatment. We 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.

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 reinforcement principles have shown the most robust empirical support for improving substance use outcomes. One such example is contingency management (CM) interventions in which nondrug alternatives are introduced into the environment with the goal of increasing the ratio of reinforcement derived from nondrug stimuli to the ratio of drug-derived reinforcement.

Cocaine dependent individuals vary in their responsiveness or sensitivity to nondrug reinforcers, however, which has been a limiting factor in the efficacy of CM interventions.

Recent lines of evidence suggest that certain medications add efficacy to CM interventions, particularly agents that target dopaminergic (DA) actions in cocaine reinforcement. A particularly promising medication that we have investigated is the DA precursor levodopa, an agent that increases the store of available central DA in DA-deficient individuals. We have observed the strongest effects of levodopa when the medication is administered in the context of CM therapy. A plausible explanation for the efficacy of this combination treatment is that levodopa, when given concomitantly with CM, enhances the saliency value of the incentives, which in turn motivates goal-directed behavior (abstinence).

The proposed study is designed to replicate, predict, and extend the effects of this promising treatment approach. Cocaine dependent outpatients will participate in a randomized, 2-group (levodopa vs. placebo), double-blind clinical trial. Abstinent-based contingency management procedures will serve as the behavioral therapy platform for both treatment groups. Potential treatment predictors related to attentional bias and motivation will be assessed at baseline and during treatment. We hypothesize that CM+levodopa will be more effective than CM+placebo in reducing cocaine use and that the effects of CM+levodopa will be significantly associated with levels of attentional bias and motivation at pretreatment and during treatment. Finally, we expect to demonstrate that continued levodopa treatment (versus placebo) following discontinuation of CM extends abstinence duration.

This study is expected to validate the usefulness of a novel behavioral-pharmacological treatment and in doing so, shed light on the mechanisms underlying the synergism between DA augmentation strategies and reinforcement-based therapies.

Intervention(s) in this Clinical Trial

• Drug: levodopa
  • 800/200 mg/d levodopa carbidopa
• Drug: Placebo
  • Placebo

Arms, Groups and Cohorts in this Clinical Trial

• Experimental: 1
  • Levodopa pharmacotherapy
• Experimental: 2
  • Placebo

Primary Measures

• Confirmed abstinence from cocaine
  • Time Frame: 12 weeks of treatment
    Safety Issue?: No

Inclusion Criteria:

• between 18 and 60 years of age
• meet 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.

Gender Eligibility for this Clinical Trial: Both

Minimum Age for this Clinical Trial: 18 Years

Maximum Age for this Clinical Trial: 60 Years

Are Healthy Volunteers Accepted for this Clinical Trial?: No

Lead Investigator: The University of Texas Health Science Center, Houston Other

Overall Clinical Trial Officials and Contacts

Joy M Schmitz, Ph.D. Principal Investigator University of Texas at Houston  

Overall Contact: Laura B Madden-Fuentes, B.A. 7135002563 Laura.MaddenFuentes@uth.tmc.edu

Information obtained from ClinicalTrials.gov on February 12, 2012

Link to the current ClinicalTrials.gov record. http://clinicaltrials.gov/show/NCT00713583

Study ID Number: 1R01DA023608-01

ClinicalTrials.gov Identifier: NCT00713583

Health Authority: United States: Federal Government