Thyroid Agents Flashcards
Levothyroxine
T4
Tx of Choice
Rx: Hypothyroidism
MOA: activation of T3 receptors
SE: hyperthyroidism
CAD: hypothyroidism is protective – Tx can cause arrhythmias, angina, MI
Liothyronine
T3
Rx: Hypothyroidism
MOA: activation of T3 receptors
SE: hyperthyroidism (Geriatric: a. fib. / osteoporosis)
CAD: hypothyroidism is protective – Tx can cause arrhythmias, angina, MI
Liotrix
T3 + T4
Rx: Hypothyroidism
MOA: activation of T3 receptors
SE: hyperthyroidism
CAD: hypothyroidism is protective – Tx can cause arrhythmias, angina, MI
Methimazole
Thioamide
Rx: Hyperthyroidism
MOA: inhibition of peroxidase reaction / iodination / couple of the iodotyrosines
SE: rash, N/V, altered taste and smell
Propylthiouracil
Thioamide
Rx: Hyperthyroidism / hyperthyroidism in pregnancy / Tx for thyroid storm
MOA: inhibition of peroxidase reaction / iodination / couple of the iodotyrosines
SE: severe hepatitis, rash, N/V, altered taste and smell
Potassium Iodide
Iodide
Rx: hyperthyroidism / thyroid storm (b/c of rapid onset) / pre-op for surgery (↓ vascularity, size of gland)
MOA: inhibits proteolysis of thyroglobulin / inhibit iodinification at higher doses
SE: cold-like symptoms (HA, cough)
only inhibit for 2-8 weeks
(↓ Na/I transporter expression)
withdrawal produces thyrotoxicosis
Lugol’s Solution
5% Iodine + 10% KI
Rx: hyperthyroidism / thyroid storm (b/c of rapid onset) / pre-op for surgery (↓ vascularity, size of gland)
MOA: inhibits proteolysis of thyroglobulin / inhibit iodinification at higher doses
SE: cold-like symptoms (HA, cough)
only inhibit for 2-8 weeks
(↓ Na/I transporter expression)
withdrawal produces thyrotoxicosis
Radioactive Iodine (131-I)
Rx: hyperthyroidism
MOA: radioactive iodine concentrates in thyroid, B rays destroy parenchymal cells while gamma rays pass through tissue for Dx measurement
SE: hypothyroidism
Contraindicated in pregnancy (can cross placenta)
Perchlorate (ClO4-)
Rx: amiodarone-iodine induced thyrotoxicosis
MOA: inhibits energy-dependent uptake of iodide into the thyroid cell that is mediated by Na/I symporter
SE: aplastic anemia
Pertechnetate (TcO4-)
Rx: amiodarone-iodine induced thyrotoxicosis
MOA: inhibits energy-dependent uptake of iodide into the thyroid cell that is mediated by Na/I symporter
Thiocyanate (SCN-)
Rx: amiodarone-iodine induced thyrotoxicosis
MOA: inhibits energy-dependent uptake of iodide into the thyroid cell that is mediated by Na/I symporter
Propranolol
Beta-blocker
Rx: hyperthyroidism
MOA: antagonize B1 and B2 receptors / inhibit converstion of T4 -> T3
Diltiazem
Rx: control tachycardia in asthmatic
Barbiturates
Increase T4 metabolism
Bile acid sequestrants
increase biliary T4 excretion
