PROLIA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PROLIA (PROLIA).
Denosumab is a human monoclonal IgG2 antibody that binds to RANKL (receptor activator of nuclear factor kappa-B ligand), preventing its interaction with RANK on osteoclast precursors and osteoclasts. This inhibits osteoclast formation, function, and survival, thereby decreasing bone resorption and increasing bone mass.
| Metabolism | Denosumab is a monoclonal antibody and is not metabolized by hepatic enzymes. It is eliminated via the reticuloendothelial system and undergoes catabolism to small peptides and amino acids. |
| Excretion | Primarily cleared via the reticuloendothelial system. No significant renal or biliary excretion; degradation to small peptides and amino acids. |
| Half-life | Terminal half-life approximately 26 days (range 20-34 days). This long half-life allows for every-6-month subcutaneous dosing and persists for up to 6 months after discontinuation. |
| Protein binding | No specific protein binding; denosumab is a monoclonal antibody, binding occurs via target (RANKL) rather than plasma proteins. Essentially 100% of denosumab in circulation is unbound to transport proteins. |
| Volume of Distribution | 0.036 L/kg (approximately 2.5 L for a 70 kg individual), indicating primary distribution within the vascular space, consistent with a large antibody. |
| Bioavailability | Subcutaneous: 82% (range 75-90%) relative to intravenous administration. Absolute bioavailability not determined due to lack of IV formulation; relative bioavailability established from pharmacokinetic studies. |
| Onset of Action | Subcutaneous: Reduction in bone resorption markers (e.g., sNTX) by 12 hours, maximal reduction by 1 month; clinical fracture risk reduction begins after 6-12 months of treatment. |
| Duration of Action | Bone resorption markers remain suppressed for at least 6 months after a single subcutaneous dose; clinical effect on fracture risk lasts for the duration of treatment (6-month dosing interval). After discontinuation, bone turnover rebound occurs within 6-12 months. |
60 mg subcutaneously every 6 months.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for any degree of renal impairment, including dialysis. |
| Liver impairment | No formal studies; no specific dose adjustment recommendations based on Child-Pugh class. |
| Pediatric use | Safety and efficacy not established; not recommended in pediatric patients. |
| Geriatric use | No dose adjustment required based on age; consider overall fracture risk and renal function (which may decline with age). |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PROLIA (PROLIA).
| Breastfeeding | No human data available; denosumab is likely excreted in breast milk (M/P ratio unknown). Theoretical risk of immunosuppression and bone development effects in infant. Decision to breastfeed should consider potential for adverse reactions. |
| Teratogenic Risk | Prolia (denosumab) is classified as Pregnancy Category D. In first trimester, there is limited data but potential for skeletal abnormalities due to RANKL inhibition. In second and third trimesters, exposure may cause fetal skeletal malformations and delayed ossification. Use contraindicated in pregnant women. |
■ FDA Black Box Warning
Denosumab (Prolia) does not have a black box warning. However, its counterpart Xgeva (denosumab 120 mg) carries a warning for severe hypocalcemia, which is included as a precaution for Prolia as well.
| Common Effects | Musculoskeletal bone muscle or joint pain Pain in extremities Nerve pain Constipation Rash Urinary tract infection |
| Serious Effects |
["Hypocalcemia (pre-existing)","Pregnancy (may cause fetal harm based on animal studies; consider alternative treatments)","Known hypersensitivity to denosumab or any component of the formulation"]
| Precautions | ["Severe and symptomatic hypocalcemia: correct pre-existing hypocalcemia prior to initiation; monitor calcium levels during therapy, especially in patients with renal impairment or predisposing factors","Osteonecrosis of the jaw (ONJ): perform dental examination before therapy; avoid invasive dental procedures during treatment","Atypical femoral fractures: evaluate for thigh or groin pain; discontinue if stress fracture is suspected","Serious infections: may increase risk of serious infections, including skin infections and endocarditis; consider benefit-risk in patients with chronic infections or immunocompromised","Dermatologic adverse reactions: dermatitis, rash, and eczema have been reported","Hypersensitivity reactions: angioedema, erythema multiforme, and urticaria reported","Renal impairment: patients with severe renal impairment (CrCl <30 mL/min) or receiving dialysis are at higher risk for hypocalcemia"] |
Loading safety data…
| Fetal Monitoring |
| Monitor maternal serum calcium levels regularly due to risk of hypocalcemia. Assess fetal bone development via ultrasound if exposure occurs. For neonates, monitor for hypocalcemia, tetany, and bone abnormalities. |
| Fertility Effects | Denosumab may impair fertility based on animal studies showing effects on male and female reproductive organs. In humans, no specific fertility studies; however, reversible menstrual irregularities may occur due to decreased serum calcium. |