This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: A.N.S., Subject name: Pharmacology
Which of the following agents scan cause recurrent fall in elderly patient with postural hypotension: 
Select and explain. 
A. Methoxamine, B. Prazosin, C. Metformin, D. Acarbose
B: Prazosin
Answer: B: Prazosin 
Explanation: (Ref: Goodman & Gillman 13th ed. P 208-209)Prazosin is one of the non-selective alpha 1 antagonists used for treatment of hypertension and BPH.DOC for HTN + BPH: PrazosinDOC for BPH: Silodosin (selective a1a agonist)Side effect:# Marked Postural hypotension (orthostatic/first dose hypotension), syncope - can cause recurrent falls. Therefore, it is given at bedtime# Retrograde ejaculation