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': 'LD 50/ ED 50 is ? \nSelect and explain. \nA. Therapeutic index, B. Bioavailability, C. Potency, D. Efficacy', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Therapeutic index Therapeutic index Drugs usually have more than one action. The maximal response for different action of a drug may be different ie the DRCs (Dose response curves) for different effects of a drug may be different. The extent of separation of DRCs of a drug for different effects is a measure of its selectivity, e.g. the DRCs for bronchodilatation and cardiac stimulation are quite similar in case of isoprenaline but far apa in case of salbutamol - the latter is more selective. The gap between the therapeutic effect DRC and the adverse effect DRC defines the safety margin or the therapeutic index.", 'role': 'assistant'}]