A 58-year-old man with a history of hypertension and coronary artery disease presents for elective laparoscopic cholecystectomy. His baseline blood pressure is 145/92 mmHg and heart rate 88 bpm. During pre-induction assessment, you note he is anxious. After pre-oxygenation, you administer an IV induction agent. Within 30 seconds of administration, his blood pressure drops to 95/58 mmHg, heart rate increases to 110 bpm, and he develops transient apnea. Which induction agent was most likely used?