This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Pharmacology
Which of the following is not used in the treatment of pulmonary hypeension? 
Select and explain. 
A. Calcium channel blockers, B. Alpha blockers, C. Prostacyclins, D. Endothelin receptor antagonists
B: Alpha blockers
Answer: B: Alpha blockers 
Explanation: Alpha blocker like prazosin, doxazosin, tamsulosin have no role in pulmonary hypeension Prostacyclin I2 analogs, endothelin antagonists like macicentan are used in pul.HTN CCBs- cause vasodilation thereby providing benefit in Pul. HTN sildenafil, tadalafil- PDE5 inhibitors are also used Ref: KD Tripathi 8th ed