This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Pharmacology, Subject name: Pharmacology
[{'content': 'A drug that shifts dose response curve to left has: \nSelect and explain. \nA. More efficacy, B. More potency, C. More safety, D. None', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B. More potencyPosition of curve indicates potency and height of curve indicates efficacy. Left ward shift indicates increase in potency of the drug.Potency: amount of drug necessary to produce a given response.a. EC50 - The concentration of drug producing an effect that is 50 percent of the maximum is used to determine potency and is commonly designated as the EC50 . The smaller the EC50 , more is the potency of a drugb. Potency is given by position on DRC. The more leftward the curve, the more potent is drugEfficacy: maximum response produced by any dose of a druga. It is analogous to the maximal velocity (Vmax ) for a reactionb. In clinical setting, efficacy is more important than drug potencyc. Efficacy is given by height of DRC. Higher the curve, more efficacious is the drug', 'role': 'assistant'}]