Exam 4 — High-Stakes Clinical Judgment (Pharmacology)

68M with epilepsy and a mechanical heart valve. Post-discharge day 14. Vitals: BP 130/80, HR 85, Temp 98.2°F, RR 18, SpO2 96%. Labs: INR 1.2 (Target 2.5-3.5), Hgb 14.5, Plt 250k. Subjective: 1. "I haven't missed a single dose of any of my pills." 2. "I feel fine." Objective: No signs of bleeding or clotting. INR is critically subtherapeutic.. Medications: Warfarin 5mg daily, Phenytoin 100mg TID. Change: Phenytoin started 2 weeks ago. Select the 3 priority actions.