denosumab
Brand: Prolia, Xgeva
Prototype Drug
Drug Class: RANK ligand (RANKL) inhibitor
Drug Family: bone agent
Subclass: anti-RANKL monoclonal antibody
Organ Systems: endocrinemusculoskeletalhematology-oncology
Mechanism of Action
Human monoclonal antibody that binds RANKL, preventing it from binding RANK on osteoclast precursors and mature osteoclasts. This blocks osteoclast formation, function, and survival, profoundly reducing bone resorption. Unlike bisphosphonates, it does not incorporate into bone and its effect is fully reversible upon discontinuation.
RANKL (receptor activator of NF-kB ligand)
Indications
- osteoporosis (Prolia: postmenopausal women, men, glucocorticoid-induced)
- bone metastases (Xgeva: giant cell tumor, solid tumors, multiple myeloma)
- prevention of skeletal-related events in malignancy
Contraindications
- hypocalcemia (must be corrected before treatment)
- hypersensitivity
Adverse Effects
Common
- back pain
- musculoskeletal pain
- hypocalcemia
- hypophosphatemia
Serious
- severe hypocalcemia (especially in CKD or vitamin D deficiency)
- osteonecrosis of the jaw (Xgeva doses higher risk)
- atypical femoral fractures
- serious infections (cellulitis, endocarditis)
- rebound vertebral fractures upon discontinuation
Pharmacokinetics (ADME)
| Absorption | subcutaneous injection (Prolia every 6 months; Xgeva every 4 weeks) |
| Distribution | Vd ~46–50 mL/kg |
| Metabolism | proteolytic catabolism (IgG2 antibody) |
| Excretion | proteolytic degradation; no renal excretion |
| Half-life | 25–28 days (Prolia); shorter for Xgeva |
| Onset | days to weeks (bone marker changes) |
| Peak | 10 days post-injection |
| Duration | 6 months (Prolia); shorter with Xgeva |
| Protein Binding | not applicable |
| Vd | 46–50 mL/kg |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| calcium and vitamin D supplements | supplementation required to prevent hypocalcemia; must be prescribed with denosumab | beneficial |
| other immunosuppressants | additive immunosuppression increases infection risk | moderate |
Nursing Considerations
- MUST correct hypocalcemia before administration; calcium and vitamin D supplementation is mandatory during treatment.
- Prolia is administered SC 60 mg every 6 months; inject in upper arm, upper thigh, or abdomen.
- Critical safety concern: do NOT abruptly discontinue denosumab for osteoporosis without transitioning to another antiresorptive agent — rebound vertebral fractures (multiple, severe) can occur within 7–12 months of stopping.
- Assess dental health and ensure any necessary dental procedures are completed before initiating; ONJ risk is present but lower than with IV bisphosphonates at oncologic doses.
Clinical Pearls
- Unlike bisphosphonates, denosumab has no renal dose restriction and is therefore preferred in patients with advanced CKD (eGFR <35 mL/min), but requires careful calcium monitoring due to enhanced hypocalcemia risk in CKD.
- The rebound fracture phenomenon upon denosumab discontinuation is unique among osteoporosis treatments; transition planning to bisphosphonate or other agent is mandatory when stopping denosumab.
Safety Profile
Pregnancy contraindicated
Lactation avoid
Renal Adjustment Not required
Hepatic Adjustment Not required
TDM Not required
Concordance Terms
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