A 58-year-old man with a history of hypertension and type 2 diabetes mellitus presents for elective laparoscopic cholecystectomy. His baseline blood pressure is 145/92 mmHg and heart rate is 88 bpm. During pre-operative assessment, you note he is on metoprolol and amlodipine. After pre-oxygenation and standard monitoring, induction is initiated. Within 30 seconds of IV administration of the induction agent, his blood pressure drops to 95/58 mmHg and heart rate increases to 105 bpm. The patient remains unconscious and airway is secured without difficulty. Which induction agent was most likely used?