This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti Thyroid, Subject name: Pharmacology
[{'content': 'Mechanism of action of prophylthiouracil - \nSelect and explain. \nA. Prevents synthesis of thyroglobulin, B. Prevents iodine trapping, C. Prevents release of T4 & T3, D. Inhibits coupling', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., Inhibits coupling o Propylthiouracil blocks thyroxine synthesis by inhibiting thyroid peroxidase, and preventing oxidation of iodide/ iodotyrosyl residues, there by1) Inhibit iodination of tyrosine residue in thyroglobulin.2) Inhibit coupling of MIT and DIT to form T3 & T4.o Propylthiouracil also inhibit the peripheral conversion of T4 to T3", 'role': 'assistant'}]