Impulsivity and Stimulant Administration

Study Overview
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Brief Summary
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Examine the interaction between stimulants, such as cocaine and methylphenidate, and impulsivity.

Official Title
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Impulsivity and Stimulant Administration

Conditions
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Cocaine Dependence, Impulsivity

Intervention / Treatment
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* Drug: cocaine hydrochloride
* Drug: methylphenidate


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: age 18 - 50 years, voluntary, written, informed consent, physically healthy by medical history, physical, neurological, ECG, and laboratory examinations, DSM-IV criteria for Cocaine Abuse (305.60) or Cocaine Dependence (304.20) recent street cocaine use in excess of amounts to be administered in the current study, intravenous and/or smoked (crack/ freebase) use, positive urine toxicology screen for cocaine, for females, non-lactating, no longer of child-bearing potential (or agree to practice effective contraception during the study), and a negative serum pregnancy (β-HCG) test. Exclusion Criteria: Other drug dependence (except nicotine) as determined by urine toxicology or interview < 1 year of cocaine dependence, a primary major DSM-IV psychiatric diagnosis (schizophrenia, bipolar disorder, etc.), unrelated to cocaine, a history of significant medical (cardiovascular) or neurological illness, ie prior myocardial infarction, current active symptoms of cardiovascular disease / angina, evidence of cocaine-related cardiovascular symptoms, prior arrhythmias or need for cardiovascular resuscitation, neurovascular events such as transient ischemic attacks, stroke, and/or seizures Parameters re: elevations in vital signs are now explicitly specified under Safety features built into our one-day self-administration paradigm). current use of psychotropic and/or potentially psychoactive prescription medication, seeking treatment for drug abuse/dependence (for experimental cocaine component), physical or laboratory (β-HCG) evidence of pregnancy. current use of any medication (prescription or over-the-counter) determined to cause potential drug interactions by the study physicians.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 50 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Factorial Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Stimulant<br>Cocaine and Methylphenidate | Drug: cocaine hydrochloride<br> <br> Drug: methylphenidate<br> <br> |
| Placebo Comparator: Placebo<br>methylphenidate | Drug: methylphenidate<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mean cocaine inter-infusion interval | Subjects complete three separate 60 minute long binge cocaine self administration sessions (low dose 8mg/70kg, medium dose 16mg/70kg, and large dose 32mg/70kg). Mean inter-infusion intervals (time between cocaine boluses) are then averaged by adding all intervals within each session and dividing by 60. Intervals during which pump access is withheld (due to increase in vital signs) will be excluded. Data on cocaine self-administration (total number of responses, infusions, and III), subjective effects, and vital signs will be checked for normality prior to analysis using Kolmogorov-Smirnov statistics and normal probability plots. The significance level for all statistical tests will be set at p<.05. | 3 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Stop Signal Reaction Time (Impulsivity) | The Dependent measures pertinent to the effects of an acute/chronic exposure to stimulants (methylphenidate/cocaine) on measures of impulsivity will be analyzed using a mixed design ANOVA. This design will have a within subjects variable to study the effects of an acute exposure to stimulants (methylphenidate vs. placebo) and a between subjects variable to study the effects of a chronic exposure to stimulants (cocaine dependent subjects vs. healthy controls). | 5 years | 
| Inter-Temporal Choice (Impulsivity) | The Dependent measures pertinent to the effects of an acute/chronic exposure to stimulants (methylphenidate/cocaine) on measures of impulsivity will be analyzed using a mixed design ANOVA. This design will have a within subjects variable to study the effects of an acute exposure to stimulants (methylphenidate vs. placebo) and a between subjects variable to study the effects of a chronic exposure to stimulants (cocaine dependent subjects vs. healthy controls). | 5 years |