This research study evaluates the effects of anFDA-approved medication Gabapentin in individuals with Bipolar Disorder who smoke marijuana. Participants in the study will will be assigned to take either Gabapentin or a matched placebo. Study medication will be taken for 17 days. There will be 5 study visits, with 2 MRI brain imaging scans completed. Questionnaires and clinical interview measures will be completed at study visits along with consistent assessment of potential side effects from study medication.

This Phase II clinical research study evaluates both the safety and effectiveness of an FDA-regulated medication presently in the initial stages of development for alcohol use disorder treatment (GET73), and will test whether GET73 alters brain chemicals and function, response to alcohol ingestion, and the desire for alcohol. Participants will be randomly assigned to one of two medication treatment groups (GET73 or placebo). Study medication will be taken for 8 days, with approximately 4 study visits, and a "bar-lab" procedure and 2 MRI brain imaging scans will be completed. Questionnaires and clinical interview measures will be completed at study visits along with consistent assessment of potential side effects from study medication.