This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Fastest acting antithyroid drugs ? 
Select and explain. 
A. Iodides of Na/ K, B. Propylthiuracil, C. Methimazole, D. Nitrates
A: Iodides of Na/ K
Answer: A: Iodides of Na/ K 
Explanation: Ans. is 'a' i.e., Iodides of Na Iodine and Iodides Iodine is the fastest acting thyroid inhibitor Most impoant action is inhibition of hormone release (thyroid constipation); but all facets of thyroid synthesis may be affected. Excess iodide inhibits its own transpo in thyroid cells and may alter the redox potential of cells, thus interfering iodination - reduced T4/T3 synthesis (Wolff-chaikoff effect).