Antithyroid Drugs - PBSci 7

Thionamides

Inhibit TPO to reduce iodination and coupling

Thionamides

Can cause side effects including rash, agranulocytosis, and hepatotoxicity

Thionamides

PTU is preferred in the 1st trimester of pregnancy due to lower teratogenic risk

Thionamides

Methimazole is preferred in the 2nd and 3rd trimesters due to lower liver toxicity risk

Iodides

Work via high-dose iodide causing the Wolff-Chalkoff effect to block hormone release

Iodides

Can cause side effects like rash, metallic taste, salivary gland swelling, and iodism

Iodides

Are contraindicated in pregnancy as they can cause fetal goiter and hypothyroidism

Radioactive iodine (I-131)

Works via beta-emission to destroy thyroid tissue through selective uptake

Radioactive iodine (I-131)

Main side effects are hypothyroidism and thyroiditis

Radioactive iodine (I-131)

Is absolutely contraindicated in pregnancy as it crosses the placenta and causes fetal thyroid ablation

Beta-blockers

Work by controlling symptoms like reducing heart rate and tremor

Beta-blockers

Can cause side effects including bradycardia, bronchospasm, and fatigue

Beta-blockers

Can be used short-term in pregnancy for symptom relief but may cause fetal growth restriction

Glucocorticoids

Work by reducing T4 to T3 conversion and providing anti-inflammatory effects

Glucocorticoids

Generally avoided in pregnancy unless for severe cases like thyroid storm

Lithium

Inhibits thyroid hormone release as its mechanism of action

Lithium

Should be avoided in pregnancy due to teratogenic effects like Ebstein's anomaly

Cholestyramine

Increases fecal excretion of thyroid hormones as its mechanism

Cholestyramine

Is safe in pregnancy as it is not absorbed systemically

Thionamides

Methimazole

Thionamides

Propylthiouracil (PTU)

Radioactive Iodine

I-131

Beta-blockers

Propranolol

Beta-blockers

Esmolol

Glucocorticoids

Hydrocortisone

Glucocorticoids

Dexamethasone