Pharmacology General cbf20617 Which of the following drugs inhibit 5'– deiodinase? A Propylthiouracil B Methimazole C Lugol's iodine D Radioactive iodine High-Yield Explanation For the peripheral conversion of T1 to T3, the enzyme needed is 5'-deiodinase. It is inhibited by Propylthiouracil Propanolol Amiodarone.