Modafinil vs Placebo for the Treatment of Methamphetamine Dependence

This application proposes a placebo-controlled double-blind trial of modafinil, on a platform of contingency management (CM) and individual cognitive-behavioral counseling (CBT once weekly individual session), for the treatment of methamphetamine dependence. Modafinil is a medication warranting evaluation as a treatment for MA dependence. It has a half-life of approximately 15 hours and reaches steady state in 2-4 days (Package insert) and will likely require once daily dosing, which reduces problems with medication adherence. Modafinil has potent psychiatric and behavioral effects that include brightening mood (Menza et al., 2000; Ninan et al., 2004), improving cognition (Turner et al., 2004a, b; 2003), improving impulse control (Turner et al., 2003; Turner et al., 2004a), and countering fatigue (Beusterien et al., 1999, Stahl et al., 2003). These effects neatly counterbalance effects produced by MA withdrawal (Newton et al., 2004) and may have particular value in ameliorating the negative reinforcing properties of MA, i.e., when MA is used to immediately relieve depressed mood due to recent abstinence (Peck et al., 2005b). CM is a behavioral intervention that effectively helps substance abusers to initiate abstinence, particularly from cocaine (Higgins et al., 1993; Higgins et al., 2000; Higgins et al., 1991) and from methamphetamine (Roll \& Shoptaw, in press; Shoptaw et al., 2005). As well, CM has been shown to reduce substance abuse and optimize the effects of medications in reducing substance abuse (Carroll, 2004; Shoptaw et al., 2002). The objective of this study is to determine whether modafinil reduces methamphetamine use and concomitant physical and psychological symptoms more effectively than placebo when administered in conjunction with CM and CBT. The purpose of this project is to evaluate whether methamphetamine abusers seeking outpatient treatment demonstrate significantly significant reductions of methamphetamine when randomly assigned to receive modafinil (400mg qd) in combination with CM and weekly CBT compared their peers randomly assigned to receive placebo in combination with CM and weekly CBT.

Research Hypotheses:

1. Participants receiving active experimental drug (modafinil 400mg) will demonstrate statistically significant reductions in methamphetamine use over participants receiving placebo. Methamphetamine use outcomes will be measured using urine samples and analyzed with the following indices: Treatment Effectiveness Score, the Joint Probability Index, self-report of methamphetamine use verified by urine drug screening, and the longest uninterrupted period of methamphetamine abstinence. Primary analyses will be conducted using modeling approaches (Generalized Estimation Equations, Markov Chain Transition Models) depending upon the structure of the dataset. Self-report of methamphetamine use will be analyzed using the Addiction Severity Index drug composite scale and Substance Use Inventory (SUI).
2. Participants receiving active experimental drug will remain in treatment for significantly longer periods compared to participants receiving placebo. Retention will be measured by the number of days in the protocol and analyzed using survival analysis.
3. Specifically, participants with mild cognitive dysfunction (as measured as <=1 SD below the published mean for the MicroCog assessments) receiving modafinil (400mg) will demonstrate significantly greater overall retention, and attendance to CBT sessions than those participants with cognitive function measured at greater than 1 SD below the mean for the MicroCog assessments who are receiving placebo.
4. Participants receiving active experimental drug (modafinil 400mg) will demonstrate statistically significant reductions in reported methamphetamine craving over participants receiving placebo. Craving outcomes will be measured using a visual analogue scale.
5. Participants receiving active experimental drug (modafinil 400mg) will demonstrate statistically significant reductions in withdrawal symptoms and somatic complaints compared to participants receiving placebo. These outcomes will be measured using the BSI, the Beck Depression Inventory-II, and the Quality of Well-Being scale.

Exploratory analyses will also be conducted to identify potential genetic variants associated with treatment response to modafinil for MA dependence. Candidate genes implicated by previous research as being involved in the pathogenesis of MA dependence and/or the molecular mechanism of modafinil (for example, genes for neurotransmitter receptors and transporters, including dopamine, norepinephrine, GABA, and glutamate, as well as genes for enzymes involved in the metabolism of these neurotransmitter, such as catechol-O-methyltransferase and monoamine oxidase A) will be sequenced in order to determine the frequency of known single nucleotide polymorphisms (SNPs), as well as potentially identify novel SNPs, in these genes among MA dependent participants. Initial analyses will focus on genes involved in the dopaminergic pathway, given the importance of dopamine in the neurobiology of MA dependence, but additional genes may also be assessed. SNPs associated with response to modafinil will be identified in order to generate hypotheses for future pharmacogenomic studies.