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
All of the following statements regarding theophylline are true except: 
Select and explain. 
A. Increases cAMP, B. Inhibits phosphodiesterase, C. Increase in dose is required in smokers, D. Increase in dose is required in cardiopulmonary disease
D: Increase in dose is required in cardiopulmonary disease
Answer: D: Increase in dose is required in cardiopulmonary disease 
Explanation: Theophylline is a methylxanthine , used in the treatment of bronchial asthma. Its dose has to be reduced in elderly (age > 60years), in congestive hea failure, pneumonia and liver failure. Ref: Essentials of Medical Pharmacology, 5th Edition, Page 203