This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Asthma, Subject name: Pharmacology
[{'content': 'Theophylline levels are increased in all, except \nSelect and explain. \nA. Erythromycin, B. Smoking, C. Cimetidine, D. CHF', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Smoking Smoking induces theophylline metabolism and decreases its plasma level.In certain conditions theophylline concentration is increased, so its dose has to be reduced.These conditions are - Age > 60 years CHFPneumonia Liver failureDrugs causing increased concentration of theophyllineErythromycinCiprofloxacinCimetidineOral contraceptivesAllopurinol", 'role': 'assistant'}]