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

Phase 2

Completed

Interventions: Drug: Placebo
Drug: levodopa
Behavioral: Cognitive Behavioral Therapy
Behavioral: Contingency Management

Brief 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.

Recruitment & Eligibility

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.

Arm && Interventions

Group	Intervention	Description
Levodopa pharmacotherapy	Cognitive Behavioral Therapy	Levodopa pharmacotherapy (800mg levodopa and 200mg carbidopa per day), cognitive behavioral therapy (CBT), and contingency management (CM).
Levodopa pharmacotherapy	Contingency Management	Levodopa pharmacotherapy (800mg levodopa and 200mg carbidopa per day), cognitive behavioral therapy (CBT), and contingency management (CM).
Placebo	Placebo	Placebo, cognitive behavioral therapy (CBT), and contingency management (CM).
Placebo	Cognitive Behavioral Therapy	Placebo, cognitive behavioral therapy (CBT), and contingency management (CM).
Placebo	Contingency Management	Placebo, cognitive behavioral therapy (CBT), and contingency management (CM).
Levodopa pharmacotherapy	levodopa	Levodopa pharmacotherapy (800mg levodopa and 200mg carbidopa per day), cognitive behavioral therapy (CBT), and contingency management (CM).

Primary Outcome Measures

Name	Time	Method
Confirmed Abstinence From Cocaine as Assessed by Treatment Effectiveness Score (TES)	12 weeks of treatment	The Treatment Effectiveness Score (TES) is the number of cocaine-negative urines collected out of the total scheduled urine tests for the 12-week trial (36 total scheduled urine tests per participant). The mean number of cocaine-negative urines over all time points is reported in this outcome measure.

Secondary Outcome Measures