A 28-year-old male with newly diagnosed pulmonary TB is enrolled in RNTCP. His sputum smear converts to negative by 2 months. However, at 4 months of treatment, he develops jaundice with elevated transaminases (ALT 180 U/L, AST 200 U/L, bilirubin 3.2 mg/dL). What is the most appropriate next step?