This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Pharmacology
First dose effect is seen with: 
Select and explain. 
A. Prazosin, B. Guanethidine, C. Propranolol, D. Clonidine
A: Prazosin
Answer: A: Prazosin 
Explanation: Ans. A. PrazosinFist dose effect is postural hypotension experienced by patient when he is on Alpha blocker. This effect can be minimized by taking low dose at the starting and take the medicine at bed time.