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
Low doses of aspirin used in myocardial infarction act by - 
Select and explain. 
A. Inhibiting thromboxane synthetase, B. Inhibit cyclooxygenase, C. Releasing EDRF, D. High protein binding activity
B: Inhibit cyclooxygenase
Answer: B: Inhibit cyclooxygenase 
Explanation: Ans. is 'b' i.e., Inhibit cyclooxygenase Aspirin (in low doses) ---> inhibits synthesis of TXA2 by inhibiting the enzyme cycloxygenase So that immediate precursor (prostaglandins) of TXA2 are not synthesized. o Ticlopidine, clopidogrel -4 they block ADP mediated cAMP inactivation.