<prompt> Conversion of T4 to T3 is inhibited by all exceptPropanololPropylthiouracilAmiodaroneMethimazole  <response>: Refer KDT 6e p250 Methimazole inhibits only thyroid peroxidase whereas propylthiouracil inhibits thyroid peroxidase as well as 5-deiodinase. Later is involveed in peripheral conversion of T4 to T3 