A 34-year-old married man with a 10-year history of bipolar disorder type I presents to the emergency department following a suicide attempt by pesticide ingestion 2 hours ago. He is currently alert and oriented, denies active suicidal ideation at this moment, and states he acted impulsively during a depressive episode. His wife reports he has been non-compliant with lithium for the past 3 months. Vital signs are stable. What is the most appropriate immediate next step in management?