This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Clinical Trials, Subject name: Pharmacology
Drug used for sympathectomy in experimental animals is - 
Select and explain. 
A. Guanethidine, B. Atropine, C. Diazoxide, D. Thebaine
A: Guanethidine
Answer: A: Guanethidine 
Explanation: Ans. is 'a' i.e., Guanethidine o Guanethidine is used for experimental sympthectomy.o Guanethidine a polar guanidine compound which is taken up into adrenergic nerve endings by active amine transport and has three important facets of action :Displaces NA from storage granules stochiometrically.Inhibits nerve impulse coupled release of NAEngages and blocks NA uptake mechanism at the axonal membrane,o It was used for sympathectomy in experimental animal.