Bone and Calcium Agents
High-yield Verified · Oct 2026Bone and Calcium Agents are a class of medications used for osteoporosis at high risk for fracture.
Medical view → mechanisms, drug comparisons and Step 1 pharmacology
Build bone, stop bone loss, or reset the parathyroid–calcium balance — and watch the serum calcium for every one of them.
How it works in the body
The system involved, what goes wrong, and how the drug and body interact.
01 Building bone: PTH analogs and sclerostin blockade
Parathyroid hormone (PTH) is the primary regulator of calcium and phosphate in bone and kidney. Teriparatide is PTH(1-34), and abaloparatide is an analog of PTH-related peptide; both act on the PTH receptor. The pattern of exposure decides the effect: intermittent injections stimulate new bone formation, favoring osteoblast over osteoclast activity, whereas the continuous excess of PTH in hyperparathyroidism may harm the skeleton because resorption is stimulated more than formation. Teriparatide is used beyond 2 years of a lifetime only if fracture risk stays high, and abaloparatide beyond 2 years is not recommended.
Romosozumab inhibits sclerostin, a regulator of bone metabolism; it increases bone formation and, to a lesser extent, decreases resorption. Its use is limited to 12 monthly doses, after which an antiresorptive is considered if treatment is still needed.
02 Slowing bone loss another way: denosumab, raloxifene, calcitonin
Denosumab binds RANKL, the protein osteoclasts need to form, function and survive, and keeps it from activating its receptor, RANK. Bone resorption falls and bone mass rises. Prolia is the osteoporosis product and Xgeva the oncology product (bone metastases, myeloma, giant cell tumor of bone, and hypercalcemia of malignancy refractory to bisphosphonates). They are the same drug, so a patient never receives two denosumab products at once. When Prolia is stopped, fracture risk increases, including multiple vertebral fractures, so the patient is moved to another antiresorptive.
Raloxifene is an estrogen agonist/antagonist (a selective estrogen receptor modulator): it acts as an estrogen agonist in bone, decreasing resorption and fractures, and as an antagonist in uterine and breast tissue. It treats and prevents postmenopausal osteoporosis and reduces the risk of invasive breast cancer in postmenopausal women with osteoporosis or at high risk. Calcitonin salmon is a calcitonin receptor agonist that acts mainly on bone. It is used for Paget disease and postmenopausal osteoporosis when other treatments are not suitable, and for hypercalcemia; fracture reduction has not been shown, and a possible link to malignancy means continued use is re-evaluated periodically.
03 Resetting the calcium–parathyroid balance: cinacalcet and calcitriol
The calcium-sensing receptor on the parathyroid chief cell is the main regulator of PTH secretion. Cinacalcet, a calcimimetic, makes that receptor more sensitive to extracellular calcium and so directly lowers PTH. It treats secondary hyperparathyroidism in adults on dialysis (not in kidney disease without dialysis) and hypercalcemia from parathyroid carcinoma or from primary hyperparathyroidism when surgery is not possible.
Vitamin D must be activated in the liver and then the kidney; the kidney’s 1-alpha-hydroxylase makes calcitriol, the active form. Diseased kidneys cannot make enough, and the resulting hypocalcemia and secondary hyperparathyroidism drive the bone disease of renal failure. Calcitriol, the most potent vitamin D metabolite, is given for secondary hyperparathyroidism and hypocalcemia in chronic kidney disease and for hypoparathyroidism — and in excess it causes hypercalcemia.
Drug names
* Sensipar (cinacalcet): Drugs@FDA lists Sensipar as discontinued, although Amgen’s Sensipar label is current with active NDCs (2026).
Indications
- Osteoporosis at high risk for fracture — teriparatide, abaloparatide, denosumab (Prolia) and romosozumab; glucocorticoid-induced osteoporosis — teriparatide and Prolia
- Treatment and prevention of postmenopausal osteoporosis, and reduction in risk of invasive breast cancer in postmenopausal women with osteoporosis or at high risk — raloxifene
- Paget disease of bone and postmenopausal osteoporosis when other treatments are not suitable; hypercalcemia — calcitonin salmon
- Prevention of skeletal-related events from multiple myeloma and bone metastases; giant cell tumor of bone; hypercalcemia of malignancy refractory to bisphosphonates — denosumab (Xgeva)
- Secondary hyperparathyroidism in adults on dialysis; hypercalcemia from parathyroid carcinoma or inoperable primary hyperparathyroidism — cinacalcet
- Secondary hyperparathyroidism and hypocalcemia in chronic kidney disease; hypocalcemia of hypoparathyroidism — calcitriol
Mechanism of action
Teriparatide (PTH 1-34) and abaloparatide (a PTHrP 1-34 analog) are PTH-receptor agonists; given intermittently they stimulate new bone formation. Romosozumab inhibits sclerostin, increasing bone formation and to a lesser extent decreasing resorption. Denosumab binds RANKL and prevents it from activating RANK, inhibiting osteoclast formation, function and survival. Raloxifene is an estrogen agonist in bone and an antagonist in breast and uterus. Calcitonin salmon is a calcitonin receptor agonist acting mainly on bone. Cinacalcet increases the sensitivity of the parathyroid calcium-sensing receptor to extracellular calcium, directly lowering PTH. Calcitriol is the active form of vitamin D and stimulates intestinal calcium transport.
Therapeutic effects — what you'll see working
For osteoporosis, success is rising bone mass and fewer fractures. For cinacalcet and calcitriol, success is a lower PTH with the serum calcium kept in range — neither too low nor too high.
- ↑ Bone formation
- Intermittent teriparatide and abaloparatide, and romosozumab, stimulate new bone formation; teriparatide reduces vertebral and nonvertebral fractures in postmenopausal osteoporosis.
- ↓ Bone resorption
- Denosumab blocks RANKL and raloxifene acts as an estrogen agonist in bone, decreasing resorption and increasing bone mass; raloxifene also decreases fracture incidence.
- ↓ PTH and calcium control
- Cinacalcet directly lowers PTH; calcitriol corrects the hypocalcemia and secondary hyperparathyroidism of kidney disease.
Adverse effects
Calcium moves in both directions with these drugs: denosumab and cinacalcet can drop it dangerously, while the PTH analogs and calcitriol can raise it. Three carry boxed warnings, and stopping denosumab has its own fracture risk.
Interactions
Contraindications
The contraindications follow calcium and clotting: no denosumab or romosozumab with low calcium, no cinacalcet started with calcium below normal, no calcitriol with high calcium, and no raloxifene with a history of blood clots. Hypersensitivity is a contraindication for all except raloxifene and cinacalcet.
When to hold
Assess before giving — these findings mean hold the dose and act.
Labs & levels
Nursing considerations
The RN-specific layer — each action paired with the reason it matters.
Common questions
What are Bone and Calcium Agents used for?
How do Bone and Calcium Agents work?
What are the serious side effects of Bone and Calcium Agents?
When should a nurse hold Bone and Calcium Agents, and what safety checks apply?
What labs should be monitored with Bone and Calcium Agents?
See also
Block cyclooxygenase to relieve pain, inflammation, and fever — at the price of GI bleeding, cardiovascular, and renal risk. They carry a two-part boxed warning.
Ease muscle spasm and spasticity — mostly by sedating the CNS. The defining risks are drowsiness/falls and additive depression with opioids, benzodiazepines, and alcohol.
Slow osteoclast bone breakdown to build bone density in osteoporosis. The exacting oral-administration protocol is central to nursing care — it protects the esophagus and rescues a <1% absorption.
Two different jobs: stop an acute attack vs lower uric acid long-term. Don’t stop urate-lowering therapy for a flare.
Sources
- FORTEO (teriparatide) — mechanism, osteosarcoma and hypercalcemia warnings, orthostatic hypotension, 2-year limit (FDA label) — FDA / DailyMed
- BONSITY (teriparatide) (FDA label) — FDA / DailyMed
- TYMLOS (abaloparatide) — PTHrP analog, warnings, 2-year limit (FDA label) — FDA / DailyMed
- PROLIA (denosumab) — boxed warning, hypocalcemia, fractures after discontinuation (FDA label) — FDA / DailyMed
- XGEVA (denosumab) — oncology indications, hypocalcemia (FDA label) — FDA / DailyMed
- EVENITY (romosozumab) — boxed warning, sclerostin inhibition, 12-dose limit (FDA label) — FDA / DailyMed
- MIACALCIN (calcitonin salmon) injection — indications, hypersensitivity, malignancy, lithium (FDA label) — FDA / DailyMed
- Calcitonin salmon nasal spray — nasal ulceration, nasal examinations (FDA label) — FDA / DailyMed
- EVISTA (raloxifene) — boxed warning, SERM mechanism, breast cancer risk reduction, interactions (FDA label) — FDA / DailyMed
- SENSIPAR (cinacalcet) — calcium-sensing receptor, hypocalcemia, adynamic bone disease, CYP interactions (FDA label) — FDA / DailyMed
- Calcitriol capsules — vitamin D activation, hypercalcemia, calcium × phosphate product, interactions (FDA label) — FDA / DailyMed
- The use of stems in the selection of INN for pharmaceutical substances (2018) — -mab, -ifene, calci-, -tide — World Health Organization
- Drugs@FDA — SENSIPAR and other brand marketing status — FDA (openFDA)
Reviewed by Hae Suk Lee, RN
Educational summary for nursing students. Always verify against current prescribing information and your institution's protocols before administering. Not medical advice.