Thyroid Drugs Flashcards
Thyroid Hormones
T3 - Triiodothyrine (3x more active than T4) (20% made in Thyroid, rest peripheral)
T4 - Thyroxine (100% made in thyroid)
Calcitonin
Thyroid Hormone Preparations
Liothyrine (T3)
Levothyroxine (T4)
Liotrix (T4 and T3 - 4:1)
Uses: Hypothyroidism (Cretenism, Child and Adult [Hashimoto’s]), Myxedema Coma (End Stage Untreated Hypothyroidism)
Anti-Thyroid Drugs: Thioamides
Propylthiouracil (PTU) [*Inhibits peripheral T4->T3][SE: Hepatits] [BETTER FOR PREGNANCY]
Methimazole
Carbimazole
Common MOA: Inhibit Thyroperoxidase, block iodine oxidation, coupling of MIT and DIT
Toxicity: Flat itchy rash, Agranulocytosis, Fetal Thyroid (Meth and carb only)
Anti-Thyroid Drugs: Anion Inhibitors
Perchlorate (ClO4-) Pertechnetate (TcO4-) Thiocynate (SCN-) Use: Block uptake of Iodide by gland via Competitive Inhibition of Iodide Txp SE: Aplastic Anemia
Anti-Thyroid Drugs: Iodine & Iodides [Iodine Salts]
Na Iodide
K Iodide
Lugol’s Iodide (I2 & KI)
Use: Inhibit hormone release, Preop ddrugs by decreasing vascularity, Rapid improvement of Thyrotoxic Symptoms in 2-7 days
Limitations: Thyroid Escape 2-8 weeks
TOXICITY: Pimple Rash, Swollen Salivary Glands. Rhinorrhea, Conjuctivitis, Anaphylactic Reactions, Mucous membrane ulceration
Iodine Contrast Media
Diatrizoate
Iohexol
Radioactive Iodine I-131
- PO (rapid)
- Beta Radiation on Thyroid
- Slow destruction of thyroid
- Cheap alternative to surgery
SE: Slow onset hypothyroidism in 80%
CI: Pregnancy, Young Pts
Adrenoreceptor Blocking Agents
Metaprolol
Atenolol
Propanolol
USE: Inhibit thyrotoxicosis symptoms (Palpitation, Nervousness, Tremors)
Grave’s Disease Tx
Radioactive Idine (Preferred for >21 & w/o heart disease)
Methimazol
Propylthiouracil (PTU)
Toxic Adenoma Tx
Radioiodine
Toxic Multinodular Goiter Tx
Thioamides (Methimazole, Carbimazole, PTU)
Thyroid Storm Tx
Propylthiouracil Propanolol Potassium Iodide (KI) Dilatezem (CC Blocker) Hydrocortisone SUPPORTIVE THERAPY: Fever, Heart Failure, Any Dx that precipitates storm
Amiodarone Induced Thyrotoxicosis
Type I - PTU (Iodine Induced)
Type II - Corticosteroids (Inflammatory)
Thyroid Radiation Exposure
Potassium Iodide (KI)