Agents That Affect Bone Mineral Homeostasis | Katzung & Trevor's Pharmacology: Examination & Board Review, 12e | AccessPharmacy

Which of the following drugs is routinely added to calcium supplements and milk for the purpose of preventing rickets in children and osteomalacia in adults?

(A) Cholecalciferol

(B) Calcitriol

(C) Gallium nitrate

(D) Sevelamer

(E) Plicamycin

The 2 forms of vitamin D—cholecalciferol and ergocalciferol— are commonly added to calcium supplements and dairy products. Calcitriol, the active 1,25-dihydroxyvitamin D₃ metabolite, would prevent vitamin D deficiency and is available as an oral formulation. However, because it is not subject to the complex mechanisms that regulate endogenous production of active vitamin D metabolites, it is not suitable for widespread use. The answer is A.

Which of the following drugs is most useful for the treatment of hypercalcemia in Paget’s disease?

(A) Fluoride

(B) Hydrochlorothiazide

(C) Pamidronate

(D) Raloxifene

(E) Teriparatide

Paget’s disease is characterized by excessive bone resorption, poorly organized bone formation, and hypercalcemia. Bisphosphonates and calcitonin are first-line treatments. Pamidronate is a powerful bisphosphonate used parenterally to treat hypercalcemia. The answer is C.

The active metabolites of vitamin D act through a nuclear receptor to produce which of the following effects?

(A) Decrease the absorption of calcium from bone

(B) Increase PTH formation

(C) Increase renal production of erythropoietin

(D) Increase the absorption of calcium from the gastrointestinal tract

(E) Lower the serum phosphate concentration

The active metabolites of vitamin D increase serum calcium and phosphate by promoting calcium and phosphate uptake from the gastrointestinal tract, increasing bone resorption, and decreasing renal excretion of both electrolytes. They inhibit, rather than stimulate, PTH formation. The answer is D.

A 59-year-old female was referred to your clinic for evaluation of osteopenia. She was diagnosed with adult-onset cystic fibrosis (CF). She reported being treated with prednisone 2 times in the past for CF exacerbations. Since menopause at 52 years of age, she had been treated with raloxifene for osteoporosis prevention. She also was on daily calcium and vitamin D supplementation. Her bone mineral density test revealed a T score of –1.6 at the lumbar spine, –2.2 at the left femoral neck, and –1.6 at the total left hip. Which of the following drugs can be used to reduce the fracture risk by further stimulating bone formation in this patient?

(A) Cholecalciferol

(B) Ergocalciferol

(C) Furosemide

(D) Tamoxifen

(E) Teriparatide

Cholecalciferol and ergocalciferol are precursors of vitamin D. Furosemide is a loop diuretic, which causes increased calcium excretion; tamoxifen is a selective estrogen receptor modulator (SERM) but is less selective for bone compared with raloxifene. Teriparatide increases bone formation and bone resorption; during the first 6 months, it causes a net gain in bone. Teriparatide should not be used longer than 2 years due to risk of osteosarcoma. The answer is E.

A 58-year-old postmenopausal woman was sent for dual-energy x-ray absorptiometry to evaluate the bone mineral density of her lumbar spine, femoral neck, and total hip. The test results revealed significantly low bone mineral density in all sites.

Chronic use of which of the following medications is most likely to have contributed to this woman’s osteoporosis?

(A) Lovastatin

(B) Metformin

(C) Prednisone

(D) Propranolol

(E) Thiazide diuretic

Long-term therapy with glucocorticoids such as prednisone is associated with a reduction in bone mineral density and an increased risk of fractures. The other drugs are not known to have significant effects on bone or serum calcium. The answer is C.

A 58-year-old postmenopausal woman was sent for dual-energy x-ray absorptiometry to evaluate the bone mineral density of her lumbar spine, femoral neck, and total hip. The test results revealed significantly low bone mineral density in all sites.

If this patient began oral therapy with alendronate, she would be advised to drink large quantities of water with the tablets and remain in an upright position for at least 30 min and until eating the first meal of the day. These instructions would be given to decrease the risk of which of the following?

(A) Cholelithiasis

(B) Diarrhea

(C) Constipation

(D) Erosive esophagitis

(E) Pernicious anemia

Oral bisphosphonates such as alendronate can irritate the esophagus and stomach. The risk of this toxicity is reduced by drinking water and by remaining in an upright position for 30 min after taking the medication. The answer is D.

A 58-year-old postmenopausal woman was sent for dual-energy x-ray absorptiometry to evaluate the bone mineral density of her lumbar spine, femoral neck, and total hip. The test results revealed significantly low bone mineral density in all sites.

The patient’s condition was not sufficiently controlled with alendronate, so she began therapy with a nasal spray containing a protein that inhibits bone resorption. The drug contained in the nasal spray was which of the following?

(A) Calcitonin

(B) Calcitriol

(C) Cinacalcet

(D) Cortisol

(E) Teriparatide

Calcitonin is a peptide hormone that prevents bone resorption. Salmon calcitonin is available as a nasal spray or a parenteral form for injection. The answer is A.

A 67-year-old man with chronic kidney disease was found to have an elevated serum PTH concentration and a low serum concentration of 25-hydroxyvitamin D. He was successfully treated with ergocalciferol. Unfortunately, his kidney disease progressed so that he required dialysis and his serum PTH concentration became markedly elevated.

Which of the following drugs is most likely to lower this patient’s serum PTH concentration?

(A) Calcitriol

(B) Cholecalciferol

(C) Furosemide

(D) Gallium nitrate

(E) Risedronate

In patients with chronic kidney disease that requires dialysis, the impaired production of active vitamin D metabolites compounded with elevated serum phosphate due to renal impairment leads to secondary hyperparathyroidism. Administration of the active vitamin D metabolite calcitriol acts directly on the parathyroid to inhibit PTH production. Cholecalciferol, a form of vitamin D, is not effective in patients with advanced renal disease who cannot form adequate amounts of active vitamin D metabolites. The answer is A.

A 67-year-old man with chronic kidney disease was found to have an elevated serum PTH concentration and a low serum concentration of 25-hydroxyvitamin D. He was successfully treated with ergocalciferol. Unfortunately, his kidney disease progressed so that he required dialysis and his serum PTH concentration became markedly elevated.

Although the drug therapy was effective at lowering serum PTH concentrations, the patient experienced several episodes of hypercalcemia. He was switched to a vitamin D analog that suppresses PTH with less risk of hypercalcemia. Which drug was the patient switched to?

(A) Calcitriol

(B) Cholecalciferol

(C) Furosemide

(D) Paricalcitol

(E) Risedronate

Paricalcitol is an analog of 1,25-dihydroxyvitamin D₃ (calcitriol) that lowers serum PTH at doses that rarely precipitate hypercalcemia. The molecular basis of this selective action is poorly understood but is of value in the management of hyperparathyroidism and psoriasis. The answer is D.

A 67-year-old man with chronic kidney disease was found to have an elevated serum PTH concentration and a low serum concentration of 25-hydroxyvitamin D. He was successfully treated with ergocalciferol. Unfortunately, his kidney disease progressed so that he required dialysis and his serum PTH concentration became markedly elevated.

In the treatment of patients like this with secondary hyperparathyroidism due to chronic kidney disease, cinacalcet is an alternative to vitamin D-based drugs. Cinacalcet lowers PTH by which of the following mechanisms?

(A) Activating a steroid receptor that inhibits expression of the PTH gene

(B) Activating the calcium-sensing receptor in parathyroid cells

(C) Activating transporters in the GI tract that are involved in calcium absorption

(D) Inducing the liver enzyme that converts vitamin D₃ to 25-hydroxyvitamin D₃

(E) Inhibiting the farnesyl pyrophosphate synthase found in osteoclasts

Cinacalcet is a member of a novel class of drugs that activate the calcium-sensing receptor in parathyroid cells. When this receptor is activated by cinacalcet or free ionized calcium, it activates a signaling pathway that suppresses PTH synthesis and release. The answer is B.

Chapter 42: Agents That Affect Bone Mineral Homeostasis

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Chapter 42: Agents That Affect Bone Mineral Homeostasis

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