This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Medicine
Which drug is not used in SIADH - 
Select and explain. 
A. Fludrocoisone, B. Demeclocycline, C. Desmopressin, D. Hypeonic saline
C: Desmopressin
Answer: C: Desmopressin 
Explanation: demeclocycline inhibit vasopression action in renal distal tubule.severe hyponatremia require treatment with hypeonic saline and fludrocoisone ( Harrison 17 pg 620)