Denosumab

Generic Name: Denosumab

Brand Names: Prolia (osteoporosis), Xgeva (cancer)

Denosumab is a RANK ligand inhibitor injectable medication for osteoporosis and bone metastases.

EndocrineOsteoporosisBone HealthOncology

Drug Class

RANK Ligand (RANKL) Inhibitor Monoclonal Antibody

Pregnancy

Category X for Prolia (osteoporosis indication) — denosumab can cause fetal harm based on animal data showing absent lymph nodes, abnormal bone growth, and decreased neonatal survival. Effective contraception is required for women of reproductive potential during therapy and for at least 5 months after the last dose.

Available Forms

Subcutaneous injection — Prolia (60 mg/1 mL prefilled syringe), Subcutaneous injection — Xgeva (120 mg/1.7 mL single-dose vial)

What It's Used For

Dosage Quick Reference

These are general dosage guidelines. Your doctor will determine the appropriate dose for your specific situation.

Condition	Starting Dose	Maintenance Dose
Postmenopausal osteoporosis at high fracture risk (Prolia)	60 mg SC every 6 months	60 mg SC every 6 months indefinitely or until transition to alternative therapy
Bone loss from aromatase inhibitor or androgen-deprivation therapy (Prolia)	60 mg SC every 6 months	60 mg SC every 6 months for duration of cancer therapy
Prevention of skeletal-related events from solid tumor bone metastases (Xgeva)	120 mg SC every 4 weeks	120 mg SC every 4 weeks
Giant cell tumor of bone (Xgeva)	120 mg SC on Days 1, 8, 15, 29 then every 4 weeks	120 mg SC every 4 weeks

Side Effects

Common Side Effects:

Back pain
Pain in extremities
Musculoskeletal pain
Hypercholesterolemia
Cystitis
Upper respiratory tract infection
Fatigue
Nausea

Serious Side Effects:

Hypocalcemia (can be severe)
Osteonecrosis of the jaw
Atypical femoral fractures
Multiple vertebral fractures after discontinuation
Serious infections (including skin infections)
Dermatologic reactions (eczema, dermatitis)
Anaphylaxis

Drug Interactions

Denosumab does not undergo CYP-mediated metabolism, so pharmacokinetic interactions are limited. The clinically important interactions are pharmacodynamic and immunologic.

Other antiresorptive agents (e.g., bisphosphonates, raloxifene): Concurrent use is not recommended because of overlapping antiresorptive effects, additive hypocalcemia risk, and unclear additional fracture benefit.
Calcium and vitamin D supplementation: Not an interaction in the harmful sense, but co-administration is essentially required. Patients should receive at least 1000 mg calcium and 400 IU vitamin D daily — and more if deficient — to prevent symptomatic hypocalcemia after dosing.
Immunosuppressants (e.g., corticosteroids, tacrolimus, biologics): Additive immunosuppression increases the risk of serious infections, including skin and soft tissue infections. Monitor closely for infection signs.
Drugs causing hypocalcemia (e.g., loop diuretics, cinacalcet, foscarnet): Serum calcium can drop precipitously after denosumab dosing. Correct hypocalcemia before each dose and recheck after any new hypocalcemia-inducing therapy.
Live vaccines: Not contraindicated but use cautiously — especially in patients on concurrent immunosuppressants — because of theoretical increased infection risk.

Additional Information

Denosumab is a fully human monoclonal antibody that inhibits RANKL (receptor activator of nuclear factor kappa-B ligand), used for the treatment of osteoporosis, bone loss, and bone metastases. This biologic provides potent anti-resorptive effects through targeted inhibition of osteoclast formation and function.

Mechanism of Action

Denosumab binds to RANKL, a transmembrane protein essential for the formation, function, and survival of osteoclasts. RANKL is produced by osteoblasts and stromal cells and binds to RANK receptors on osteoclast precursors, stimulating their differentiation into mature osteoclasts. By binding RANKL with high affinity, denosumab mimics the effect of the natural decoy receptor osteoprotegerin (OPG), preventing RANKL from activating RANK. This results in decreased osteoclast formation and activity, reduced bone resorption, and increased bone mass and strength. The effect is reversible upon discontinuation.

Available Formulations

Denosumab is available in two distinct products: Prolia (60 mg/mL in prefilled syringes) for osteoporosis and Xgeva (120 mg/1.7 mL in vials) for bone metastases and giant cell tumor of bone. These products are not interchangeable and have different dosing schedules. Both are administered as subcutaneous injections. The medication should be brought to room temperature before injection and can be given in the upper arm, thigh, or abdomen.

Medical Uses

Prolia (denosumab 60 mg) is FDA-approved for treatment of postmenopausal women with osteoporosis at high risk for fracture, treatment to increase bone mass in men with osteoporosis at high risk for fracture, treatment of bone loss in patients receiving androgen deprivation therapy for prostate cancer or aromatase inhibitor therapy for breast cancer at high risk for fracture, and glucocorticoid-induced osteoporosis. Xgeva (denosumab 120 mg) is approved for prevention of skeletal-related events in patients with bone metastases from solid tumors, treatment of giant cell tumor of bone, and treatment of hypercalcemia of malignancy refractory to bisphosphonate therapy.

Dosing Guidelines

For osteoporosis (Prolia), the dose is 60 mg subcutaneously every 6 months. Patients should receive adequate calcium (1000 mg) and vitamin D (at least 400 IU) daily. For bone metastases (Xgeva), the dose is 120 mg subcutaneously every 4 weeks. For giant cell tumor, Xgeva 120 mg is given every 4 weeks with additional doses on days 8 and 15 of the first month. Hypocalcemia must be corrected before initiating therapy.

Important Safety Information

Denosumab carries important safety warnings for hypocalcemia (may be severe and symptomatic), osteonecrosis of the jaw (ONJ), atypical femoral fractures, and a significant rebound effect with vertebral fractures upon discontinuation. Patients should have adequate calcium and vitamin D intake and should be monitored for hypocalcemia, especially those with renal impairment. Dental examination is recommended before starting therapy, and invasive dental procedures should be avoided if possible during treatment. Multiple vertebral fractures can occur after stopping denosumab; transition to another osteoporosis therapy is recommended.

Drug Interactions

No formal drug interaction studies have been conducted. Denosumab is not metabolized by cytochrome P450 enzymes and is unlikely to have pharmacokinetic interactions. However, hypocalcemia should be corrected before starting therapy, and patients receiving medications that can also lower calcium should be monitored closely. Concurrent use with other bone-active agents has not been studied and is generally not recommended.

Special Populations

Denosumab may cause fetal harm based on animal data; women should avoid becoming pregnant during treatment and for at least 5 months after the last dose. It is unknown whether denosumab is excreted in human breast milk. Prolia is not indicated for use in pediatric patients; Xgeva is approved for adults and skeletally mature adolescents with giant cell tumor of bone. Elderly patients do not require dose adjustment. No dose adjustment is needed for renal impairment, but patients with severe renal impairment (CrCl less than 30 mL/min) or on dialysis are at greater risk for hypocalcemia. Hepatic impairment has not been studied.

Frequently Asked Questions

Discontinuing denosumab without transitioning to another antiresorptive (such as a bisphosphonate) causes a rapid rebound in bone turnover and a sharp rise in vertebral fracture risk — including multiple fractures within months. If denosumab needs to be stopped for any reason, your provider should plan a bisphosphonate handoff before the next scheduled dose would have been due.

Both reduce osteoclast activity and fracture risk, but through different mechanisms. Bisphosphonates bind directly to bone mineral and act on osteoclasts that contact them. Denosumab is an antibody that neutralizes RANKL, the signal that activates osteoclasts. Denosumab is given by injection every 6 months, does not require dose adjustment for kidney function, and its effect dissipates within months of stopping — whereas bisphosphonates persist in bone for years.

Osteonecrosis of the jaw (ONJ) is a rare but serious condition where jaw bone becomes exposed and fails to heal — most commonly after dental extractions or invasive dental work. Before starting denosumab, schedule a dental exam and complete any needed extractions or implant work. While on therapy, maintain meticulous oral hygiene and inform any dentist of your treatment.

Denosumab abruptly suppresses bone resorption, which can cause serum calcium to drop because calcium is no longer being released from bone. Adequate intake of calcium (at least 1000 mg daily) and vitamin D (at least 400 IU, often 800–1000 IU) before and during therapy prevents symptomatic hypocalcemia, which can cause muscle cramps, tingling, and in severe cases cardiac arrhythmia.

Long-term data extend beyond 10 years, with continued benefit on bone density and fracture reduction. There is no fixed maximum duration. Decisions about long-term continuation versus transition to another agent should weigh ongoing fracture risk, side effect tolerance, and the rebound risk that follows discontinuation.

Questions to Ask Your Doctor

Consider discussing these topics at your next appointment:

✓How does my fracture risk compare with the risks of long-term denosumab therapy?
✓Do I need a dental evaluation before starting?
✓How will my calcium and vitamin D status be monitored?
✓If I ever need to stop denosumab, what is the transition plan?
✓How will we measure whether the medication is improving my bone density?

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Related Health Conditions

This medication is commonly used to treat or manage the following conditions:

Osteoporosis

Osteoporosis weakens bones due to age, hormonal changes, poor diet, medications, certain medical conditions, and lifestyle factors, increasing fracture risk even from minor incidents.

Learn More

Medical Disclaimer: This information is for educational purposes only and should not be considered medical advice. Always consult with your healthcare provider before starting, stopping, or changing any medication. Your doctor can provide personalized recommendations based on your specific health condition and medical history.