WHAT IS IT?
Propylthiouracil/PTU is an antithyroid medication that works by blocking thyroid peroxidase. This inhibits the oxidation of iodide and the organifciation/coupling of iodine which in turn inhibits thyroid hormone sysntesis (T3 and T4 can not be made).
PTU aslo blocks 5′-deiodinase which is responsible for the peripheral conversion of T4 to T3.
WHEN DO WE USE IT?
Hyperthyroidism (Graves disease), thyroid storm,. Can also be used during preganacy to prevent the conversion of T4 to T3 (not teratogenic effect unlike methimazole).
*Use in patients who can not tolerate methimazole, or for whom radioactive iodine therapy/surgery are not therapeutic options.
WHEN DO WE AVOID USING IT?
Patients with current liver damage may wish to avoid this medication (as it has hepatotoxicity).
HOW IS IT ADMINISTERED?
WHAT ARE THE SIDE EFFECTS/TOXICITY?
Skin rash, agranulocytosis, aplastic anemia, hepatotoxicity (in some cases patients have needed liver transplantation) .
ANYTHING ELSE TO KEEP IN MIND?
All of the synthetic steps of thyroid hormone synthesis are catalyzed by thyroid peroxidase.
Page Updated: 02.15.2016