Lamotrigine for bipolar disorder and comorbid cocaine dependence: A replication and extension study

Background: Bipolar disorder (BPD) is associated with high rates of substance abuse. We previously reported favorable results with lamotrigine in 30 patients with BPD and cocaine dependence. This report examines lamotrigine therapy in an additional 32 cocaine dependent patients. Data on these 32 participants are presented as a replication study. In addition, we extend the previous findings by combining data from both groups, and by exploring predictors of response. Method: Participants received a baseline evaluation and assessment for up to 36 weeks with the 17-item Hamilton Rating Scale for Depression (HRSD₁₇), Young Mania Rating Scale (YMRS), Brief Psychiatric Rating Scale (BPRS₁₈), and Cocaine Craving Questionnaire (CCQ). Urine samples were obtained, and participants reported drug use during the previous week. Results: In the replication sample (n = 32), significant improvements were observed in HRSD₁₇, YMRS, BPRS₁₈, and CCQ (baseline to exit), as well as on dollars/week spent on cocaine. In the extension study, the original sample (n = 30) and the replication sample (n = 32) were combined for a total of 62 participants in the intent-to-treat sample. HRSD₁₇, YMRS, BPRS₁₈, and CCQ scores, as well as dollars spent on cocaine, decreased significantly. Limitations: The study has an open-label, uncontrolled design. Conclusion: Lamotrigine treatment was associated with significant improvements in mood, drug craving, and drug use. Controlled trials are needed.