2/2 Multicenter trial of combined pharmacotherapy to treat cocaine dependence

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DESCRIPTION (provided by applicant): Cocaine dependence continues to be a significant public health problem in the United States and there are no FDA-approved pharmacotherapies for cocaine use disorders. Standard psychosocial treatments for cocaine dependence yield small-to-medium effect sizes, but are not effective for many cocaine-dependent patients. Given the success in recent years in developing effective pharmacotherapies for alcohol, opioid, and nicotine use disorders, the development of effective pharmacotherapies for cocaine use disorders remains an important public health goal. Promising separate developing lines of research suggest that amphetamine and topiramate are potential pharmacotherapies for cocaine dependence that individually have demonstrated limited efficacy. These two medications have distinct mechanisms of action~ amphetamine increases dopamine transmission and topiramate reduces nucleus accumbens dopamine release. This combination may decrease baseline craving and cocaine-induced reinforcement. A pilot study (N=81) conducted by our research group found that the combination of mixed amphetamine salts extended-release (MAS-ER) and topiramate was effective for promoting abstinence among cocaine- dependent individuals, particularly among those with a greater frequency of use at baseline. This promising result warrants confirmation in a larger randomized placebo-controlled study. Using the PAR-10-099 "Collaborative Clinical Trials in Drug Abuse" mechanism, the proposed project is a two site randomized double- blind trial. We aim to study cocaine-dependent individuals who use cocaine frequently and for whom the combination of MAS-ER and topiramate was shown to be effective. The goal of this phase III clinical trial is to build on our promising pilot study results and examine the efficacy of the combination of MAS-ER and topiramate on cocaine consumption using an abstinence-initiation model. Specific Aim: To determine the efficacy of MAS-ER and topiramate in promoting cocaine abstinence among cocaine-dependent patients. Primary Hypothesis: MAS-ER and topiramate will significantly promote abstinence from cocaine use as compared to placebo. The primary outcome measure will be three consecutive weeks of cocaine abstinence at the end of the trial as recorded by the Timeline Follow-Back method confirmed by creatinine-normalized quantitative urine benzoylecgonine (BE) levels. Secondary Hypotheses: MAS-ER and topiramate will 1) significantly promote abstinence during any three consecutive weeks during the study period and be superior to placebo in reducing 2) the proportion of urine toxicology samples negative for BE~ 3) symptoms of cocaine withdrawal~ and 4) cocaine craving. Our research group is well suited to conduct this study given our extensive experience in conducting cocaine dependence pharmacotherapy clinical trials, as well as having direct experience in using MAS-ER and topiramate to treat cocaine-dependent outpatients.