This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pituitary-Hypothalmic System and Thyroid, Subject name: Pharmacology
Fastest acting anti-thyroid drug is 
Select and explain. 
A. Sodium Iodide, B. Propyl thiouracil, C. Methimazole, D. Thiocyanate
A: Sodium Iodide
Answer: A: Sodium Iodide 
Explanation: Secretion inhibitors:These are fastest acting anti thyroid drugs. NaI KI Lugol iodine Thyroid peroxidase inhibitor Carbimazole/Methimazole Propylthiouracil Thiocyanate is Na+I+sympoer (NIS) inhibitor. Highly toxic Not used clinically