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Questions and Answers
What is the primary use of levothyroxine sodium?
What is the primary use of levothyroxine sodium?
Which of the following is NOT a thioamide drug?
Which of the following is NOT a thioamide drug?
What is the recommended initial dose for elderly patients receiving thyroid hormone therapy?
What is the recommended initial dose for elderly patients receiving thyroid hormone therapy?
What condition may result from excessive thyroid hormone levels?
What condition may result from excessive thyroid hormone levels?
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Which medication is considered safe for use during pregnancy and lactation?
Which medication is considered safe for use during pregnancy and lactation?
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Which of these is a common adverse effect of thioamide drugs?
Which of these is a common adverse effect of thioamide drugs?
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What is one of the primary uses of β-adrenoceptor antagonists like Propranolol?
What is one of the primary uses of β-adrenoceptor antagonists like Propranolol?
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What is the half-life of T4 (levothyroxine) compared to T3 (liothyronine)?
What is the half-life of T4 (levothyroxine) compared to T3 (liothyronine)?
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Which of the following is a type of iodide salt used in thyroid crisis?
Which of the following is a type of iodide salt used in thyroid crisis?
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Which treatment option is commonly used for hyperthyroidism?
Which treatment option is commonly used for hyperthyroidism?
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What is the mechanism of action for radioactive iodine (I-131) in treating thyroid conditions?
What is the mechanism of action for radioactive iodine (I-131) in treating thyroid conditions?
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How long does it generally take for the maximum effect of iodide salts to manifest?
How long does it generally take for the maximum effect of iodide salts to manifest?
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Which of the following conditions is characterized by abnormal mineralization of new bone matrix?
Which of the following conditions is characterized by abnormal mineralization of new bone matrix?
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What contraindicates the use of radioactive iodine in treatment?
What contraindicates the use of radioactive iodine in treatment?
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Which of the following correctly describes osteoporosis?
Which of the following correctly describes osteoporosis?
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What is the half-life of radioactive iodine (I-131) after administration?
What is the half-life of radioactive iodine (I-131) after administration?
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What effect does Raloxifene have on postmenopausal women?
What effect does Raloxifene have on postmenopausal women?
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How is Denosumab administered?
How is Denosumab administered?
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What is the primary clinical use of Calcitonin?
What is the primary clinical use of Calcitonin?
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What is a unique characteristic of Teriparatide?
What is a unique characteristic of Teriparatide?
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How does Strontium ranelate function in the prevention of osteoporosis?
How does Strontium ranelate function in the prevention of osteoporosis?
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What is rickets primarily caused by in children?
What is rickets primarily caused by in children?
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Which of the following groups is particularly at risk for osteomalacia due to impaired vitamin D absorption?
Which of the following groups is particularly at risk for osteomalacia due to impaired vitamin D absorption?
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What is the primary mechanism of action of bisphosphonate drugs?
What is the primary mechanism of action of bisphosphonate drugs?
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Which of the following is an example of a third-generation bisphosphonate?
Which of the following is an example of a third-generation bisphosphonate?
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Estrogen helps to manage bone health by affecting which type of cells?
Estrogen helps to manage bone health by affecting which type of cells?
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Which of the following medications is indicated for the prevention and treatment of osteoporosis in postmenopausal women?
Which of the following medications is indicated for the prevention and treatment of osteoporosis in postmenopausal women?
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What role do oral calcium and vitamin D supplements play in bone health?
What role do oral calcium and vitamin D supplements play in bone health?
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Which compound is known to inhibit bone resorption while also stimulating bone formation?
Which compound is known to inhibit bone resorption while also stimulating bone formation?
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Study Notes
Pharmacology of Thyroid Hormone
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Thyroid hormone synthesis: Thyroid cells take up iodine and couple it with tyrosine residues in thyroglobulin. This creates thyroxine (T4) and triiodothyronine (T3).
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Hyposecretion (Hypothyroidism): Thyroid replacement therapy includes levothyroxine sodium (T4), typically more effective than liothyronine sodium (T3) in suppressing TSH.
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Hypersecretion (Hyperthyroidism): Treatments include antithyroid drugs, irradiation, or surgical removal of the overactive tissue.
Thyroid Hormone Preparations
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Levothyroxine and Liothyronine: Synthetic thyroid hormones used for replacement therapy. A mixture containing T4 and T3 in a 4:1 ratio (liotirix) is also available. Levothyroxine is the typical drug of choice for hypothyroidism.
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Pharmacokinetics: T4 and T3 have good absorption and are adequately absorbed orally. T4 has a longer half-life (one week) compared to T3 (two days).
Antithyroid Agents
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Thioamide drugs: Carbimazole, methimazole, and propylthiouracil (PTU). PTU is often preferred during pregnancy and lactation.
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Indicate use : used to treat Graves' disease & suppress symptoms before surgery or radioactive iodine treatment.
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Pharmacokinetics Given orally; carbimazole is metabolized to methimazole.
Other Anti-thyroid Agents
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Beta-adrenergic antagonists: Like propranolol, reduce the cardiovascular effects of hyperthyroidism (e.g., anxiety).
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Iodide salts: Immediate effects on thyroid hormone release, used in thyroid storm (acute thyrotoxicosis) and short-term treatment.
Radioactive Iodine
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Mechanism: Absorbed rapidly by the thyroid and emits beta particles to destroy thyroid tissue.
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Uses: Definitive treatment for relapses of Graves' disease, toxic multinodular goiter and toxic solitary nodule.
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Contraindications: Pregnancy and lactation.
Bone Disorders
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Osteoporosis: Reduced bone mass, leading to easy fractures. Common in postmenopausal women.
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Osteomalacia: Abnormal bone mineralization, often caused by vitamin D deficiency. Similar in children, results in rickets.
Drugs Affecting Calcium and Bone
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Cinacalcet: Activates calcium sensing receptors, lowering parathyroid hormone levels, reducing calcium levels.
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Calcitonin: Decreases calcium excretion by the kidneys and calcium absorption in the intestines; used for managing hypercalcemia and osteoporosis.
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Vitamin D: A crucial nutrient for calcium regulation; its activation converts vitamin D to its active form (calcitriol).
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Diet is an important preventative measure in maintaining a balance of bone health.
Drug Treatment of Bone Loss
- Bisphosphonates: Inhibit bone resorption, commonly used in osteoporosis prevention and treatment.
Strontium Ranelate
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Usage: Indicated for prevention and treatment of osteoporosis in postmenopausal women.
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Mechanism: Decreases osteoclastic activity and increases bone formation.
Sodium Fluoride
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Mechanism: Replaces hydroxyl groups in bone, to form fluorapatite, which is more resistant to erosion than hydroxyapatite.
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Usage: Prevents dental caries and tooth decay.
Denosumab
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Mechanism: Inhibits osteoclast activity, reducing bone resorption.
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Usage: Treats osteoporosis
Teriparatide
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Mechanism: Newer drug, a type of parathyroid hormone.
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Usage: Treats osteoporosis.
Calcium and Vitamin D
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Adequate intake: Critical for bone health in children and adults to prevent osteoporosis, primarily by consuming dairy products and taking supplements when necessary,
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Potential issues: Aging, malabsorption issues or certain medications can disrupt vitamin D metabolism, leading to bone-related issues.
Iron-Deficiency and Anemia
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Iron-deficiency Anemia (IDA): Results from insufficient iron uptake.
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Anemia of Inflammation (AI/ACD): Associated with chronic inflammation or disease.
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Description
Test your knowledge on the pharmacology of thyroid hormones, including their synthesis, effects of hypo- and hypersecretion, and treatments available. Learn about thyroid hormone preparations and the role of antithyroid agents in managing thyroid conditions.
