Orexin s Role in the Neurobiology of Substance Use Disorder

Study Description: Despite the availability of pharmacotherapy for some substance use disorders, relapse vulnerability is still a significant issue. This suggests medications with alternative mechanisms of action should be explored to address this unmet need. Substantial preclinical research indicates that orexin antagonism blunts the internally and externally triggered motivation to attain abused substances. This research project will translate these preclinical findings into the clinical domain by administering the FDA approved orexin antagonist, suvorexant, to those with a substance use disorder. Suvorexant's ability to blunt neurobiological correlates of substance misuse will be assessed. This will be assessed following acute and repeated drug administration. Baseline individual differences will be considered to determine whether neurobiological variance influences suvorexant's impact in those with nicotine dependence. In an independent arm, the interaction between suvorexant and a dopamine agonist (methylphenidate) on cognitive function will be assessed in non-smoking individuals. Objectives: The objective is to determine the acute and chronic impact of the orexin antagonist, suvorexant, on neurobiological and behavioral factors linked with substance use disorders. Whether such effects are mediated by baseline characteristics will be tested. Given suvorexant is an FDA approved treatment for insomnia, sleep will be evaluated as well in the nicotine dependent arm. Endpoints: In nicotine-dependent individuals, suvorexant's impact on brain function will be assessed several ways by evaluating: 1) resting function, 2) reactivity to drug cues, 3) reactivity to non-drug related cognitive tasks. Sleep and nicotine use will be measured throughout the study period. In those without nicotine-dependence, the impact of suvorexant and the interaction of acute methylphenidate and suvorexant on brain function will be assessed. This arm will provide insight into how suvorexant impacts reward/cognition as well as impacts the pharmacological influence of methylphenidate on those same measures.