Question 1

Which of the following drugs interacts with thyroperoxidase and NADPH oxidases to inhibit the organification of iodide?&#10;A) Perchlorate&#10;B) Propylthiouracil&#10;C) L-thyroxine&#10;D) Lithium&#10;E) Iopanoate

Accepted Answer

The thioureylene drugs propylthiouracil (PTU) and methimazole interact with thyroperoxidase and NADPH oxidases to inhibit organification of iodide and thus levothyroxine production. PTU also inhibits deiodination of T₄ to T₃, contributing to its antithyroid activity.

Question 2

Why are corticosteroids often included in the treatment of hyperthyroidism? A) To stabilize the erratic blood sugars of hyperthyroidism B) To increase the catabolism of T₄ to T₃ C) As an antiinflammatory agent for the thyroid D) To counteract the increased delta-4 steroid reductase activity E) To displace thyroxine-binding globulin from plasma proteins

Accepted Answer

Hyperthyroidism increases delta-4 steroid reductase activity, which enhances the rate of cortisol degradation. Exogenous corticosteroids alleviate this effect.

Deck 42: Thyroid and Antithyroid Drugs