Block 9 Drugs - Thyroid

Question 1

Thyrotropin (TSH, Thyrogen®)

Answer 1

MOA: Activates TSH receptor increasing thyroid hormone synthesis and secretion

USE: Diagnostic testing of thyroid function with ¹²³I

S/E: Headache

Nausea

Nervousness

Fast/irregular heartbeat

Unique: Used to detect remnant thyroid cancer in patients who have had thyroid ablation surgery

Question 2

Thyroxin (T2)

Levothryoxine; synthroid ®

Answer 2

MOA: Binds to and activates thyroid hormone receptors

USE: Used to treat hypothyroidism

TSH suppression in goiter

S/E: Allergic reaction

Chest pain

Rapid heartbeat

Sever headache

Nausea

Blurred vision

CI: DIabetest

Vascular, coronary artery or adrenal disease

Unique: May cause bone loss

Oral Preparation

Question 3

Triodothyronine (T2)

Liothyronine

Answer 3

MOA: Binds to and activates thyroid hormone receptors

USE: Used to treat hypothyroidism

Myxedema

S/E: Allergic reaction

Chest pain

Fever

Headache

Shortness of breath

Swelling of hands, ankles or feet

CI: Breast feeding

Diabetes

Heart, kidney, liver or adrenal disease

Unique: Oral and injectable (for rapid effects) preparations

Question 4

Propylthiouracil

Answer 4

MOA: Antithyroid Agent

Inhibits TPO thereby blocking tyrosine organification and T3/T4 formation

Inhibits deiodinase blocking T4 to T3 conversion

USE: Hyperthyroidism, Graves’ disease

in conjunction with ¹³¹I

Preparation for thyroidectomy (surgery)

S/E: Skin rash - common

Agranulocytosis

Aplastic anemia - rare events

Unique: Useful for treating thyroid storm

Thyrotoxic crisis

Question 5

Iodine (Iodide)

Answer 5

MOA: Antithyroid Agent

Inhibits TPO and iodotyrosine/iodothyronine synthesis

Inhibits thyroid hormone release

USE: Reduces thyroid vascularity/shrinks gland

Protection from radioactive fallout

Prophylaxis of endemic goiter

S/E: Angioedema

Fever

Arthralgia

Eosinophilia

Iodism

Dermatitis

Mental depression

Question 6

¹³¹I (Iodotope®)

Answer 6

MOA: Antithyroid Agent

Trapped in thyroid follicle colloid; ß-particles destroy parenchymal cells

USE: Noninvasive thyroid ablation for hyperthyroidism

S/E: Hypothyroidism

Unique: Radioactive isotope

Patients need to be sequestered

Question 7

Perchlorate

Answer 7

MOA: Antithyroid Agent

Inhibits iodide transport into thyroid

USE: Hyperthyroidism when other antithyroid drugs not tolerated

S/E: Agranulocytosis

Aplastic anemia

CI: Often found in drinking water and in the environment - an endocrine disruptor

Unique: Rarely used due to toxicities and frequent dosing requirement