Endocrine Flashcards
Hypothyroidism Drugs
1) Levothyroxine (T4)
2) Liothyronine
3) Thyroid desiccated
Levothyroxine (T4)
Use: Hypothyroidism
- The most common and efficacious treatment of hypothyroidism.
- Synthetic hormone is preferred due to stability, uniformity of the preparation, low cost.
- can be administered once a day
Liothyronine (T3)
Use: Hypothyroidism
- rarely used due to short half-life (24 hr)
- higher costs and difficulty in monitoring adequate plasma levels
What are the 2 general approach to treat hyperthyroidism?
1) inhibit thyroid hormone synthesis and release of thyroid hormone
2) destruction (or surgical removal) of the epithelial cells in the thyroid gland.
Thiamides
Inhibit thyroid peroxidase and thus inhibit the iodination of tyrosine to MIT and DIT (organification) and the coupling of iodotyrosines (MIT and DIT) to form T3 and T4.
The onset of action is slow since they inhibit synthesis and not release.
Their action is only apparent 3-6 weeks after initiation of therapy when the stores of T4 are depleted.
Drugs: Methimazole & Propylthiouracil
Methimazole (Tapazole®)
Treats hyperthyroidism
- drug of choice for inhibition of thyroid synthesis.
Propylthiouracil (PTU)
Treats hyperthyroidism
- used infrequently due to severe hepatitis (black box warning).
PTU also inhibits the peripheral deiodination of T4 to T3. PTU is used for severe hyperthyroidism and thyroid storms.
Iodide (Potassium iodide)
Treats: hyperthyroidism
- inhibits iodination of tyrosine
- inhibits synthesis of thyroid hormone
- inhibits release of thyroid hormone
- most significant effect is the inhibition of thyroid hormone release which produces a relatively rapid (2-7 days) decrease in serum thyroid hormone. Because of its rapid action potassium iodide is used to treat thyroid storm
- should not be used during pregnancy
Drugs that inhibit thyroid hormone synthesis and release
1) Thiamides
2) Iodide
Destruction of the epithelial cells drug
Radioactive Iodine
Radioactive iodine
- used to destroy the follicular epithelial of the thyroid gland
- administered orally and concentrated by the thyroid gland
- Contraindicated in pregnancy
Beta-Adrenergic blocking agents
- Beta blockers are frequently used as adjuncts to treat the cardiac symptoms associated with hyperthyroidism
- propranolol, metoprolol and atenolol
- reduce the cardiac symptoms, but do not treat the underlying hyperthyroidism
What is the major difference among corticosteroids between adrenal pharmacology?
the major difference among the corticosteroid is their affinities for the glucocorticoid and mineralocorticoid receptors
What can happen if you there is a sudden withdrawal of corticosteroid therapy?
can cause acute adrenal insufficiency which can be life threatening
Hormone replacement
Hydrocortisone (cortisol), prednisone and dexamethasone are used for replacement therapy in adrenal insufficiency
Patients with primary adrenal insufficiency may require fludrocortisone to replace aldosterone
What are the 2 primary regulators of calcium and phosphate?
1) PTH
2) Vit. D
PTH
MOA:regulates calcium and phosphate flux across cellular membranes in bone and kidney, resulting in increased serum calcium and decreased serum phosphate
Teriparatide (Forteo) (recombinant PTH 1-34)
used to treat osteoporosis
- Injected subcutaneously daily. Due to risk of osteosarcoma, teriparatide should be given for only 2 years (BLACK BOX WARNING)
Abaloparatide (Tymlos) (PTH hormone related protein 1-34, PTHrP)
Approved in April 2017 for use in osteoporosis
Denosumab (Prolia)
MOA: Human antibody against RANKL and inhibits the conversion of preosteoclasts to osteoclasts and inhibits osteoclast activity.
Denosumab is given subcutaneously once every 6 months
SE: hypocalcemia
TU: osteoporosis in post-menopausal women
Prostate and breast cancer (used to suppress bone loss during antigonadal therapy)
Cinacalcet (Sensipar)
MOA: sensitizes calcium-sensing receptors in the parathyroid
gland to calcium
-Increased sensitivity to calcium causes ↓PTH release and a ↓ serum calcium levels
TU: Secondary hyperparathyroidism in chronic kidney disease and parathyroid carcinoma
Bisphosphonates
MOA: Analogs of pyrophosphate that retard dissolution of hydroxyapatite crystals in bone
- Inhibit osteoclast resorption of bone
- Promotes apoptosis of osteoclasts
TU: Prevention and treatment of osteoporosis (both postmenopausal and steroid-induced osteoporosis), Paget’s disease and hypercalcemia associated with malignancy
- These drugs are poorly absorbed and less than 10% of the oral dose is absorbed from the GI tract
Drugs: “dronate”
Alendronate (Fosamax®) Risedronate (Actonel®) Etidronate (Didronel®) Zolendronate (Reclast®) Ibandronate (Boniva®) Pamidronate (Aredia®) Tiludronate (Skelid®)
SE of Bisphophonates
GI symptoms
Given in the AM after a night-long fast 30 minutes before breakfast with a large glass of water and while sitting or standing upright – this helps to reduce GI symptoms and increase absorption.
Bisphosphonates are contraindicated in patents with active upper GI disease.
Vitamin D
Steroidal-like compound produced in the skin from 7-dehydrocholesterol under the influence of UV irradiation
MOA: Aids in calcium absorption from gut Found in certain foods
Metabolism: Hydroxylated in liver to 25[OH]D3 then the kidney to 1,25 (OH)2 D3 and 24, 25 (OH)2D3
Drugs:
Ergocalciferol (vitamin D2) Cholecalciferol (vitamin D3) Calcifediol (25 [OH]D) Calcitriol (1,25 (OH)2 D3)
