This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Anatomy
Drug of choice for pneumocystis carinii is 
Select and explain. 
A. Doxycycline, B. Cotrimoxazole, C. Tetracycline, D. Dapsone
B: Cotrimoxazole
Answer: B: Cotrimoxazole 
Explanation: The treatment of choice for PCP is trimethoprim-sulfamethoxazole (TMP-SMX), given either IV or PO for 14-21 days .TMP-SMX, which interferes with the organism's folate metabolism, is at least as effective as alternative agents and is better tolerated. Ref Harrison 19th edition pg 1019 Davidson edition23rd pg 587