This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
[{'content': 'True about esmolol is: a) It is a cardioselective β–blocker b) It increases airway resistance c) It causes tachycardia d) Its t 1/2 is 4 hrs e) It has negative inotropic activity \nSelect and explain. \nA. de, B. cd, C. ae, D. bc', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Esmolol is\xa0an ultrashort acting β-blocker (t1/2 < 10 min.)\nIt is inactivated by esterases in blood.\nβ-blocker decreases heart rate and force of contraction\xa0(negative inotropic action).\nBeta blockers can precipitate or aggravate CHF.\nSelective beta 1 blocker and are less likely to cause\xa0bronchoconstriction, thus do not increase airway resistance.', 'role': 'assistant'}]