5 WARNINGS AND PRECAUTIONS
5.1 Drugs With Same Active Ingredient or in the Same Drug Class
Zoledronic Acid Injection contains the same active ingredient as found in Reclast® (zoledronic acid). Patients being treated with Zoledronic Acid Injection should not be treated with Reclast or other bisphosphonates.
5.2 Hydration and Electrolyte Monitoring
Patients with hypercalcemia of malignancy must be adequately rehydrated prior to administration of zoledronic acid. Loop diuretics should not be used until the patient is adequately rehydrated and should be used with caution in combination with zoledronic acid in order to avoid hypocalcemia. Zoledronic acid should be used with caution with other nephrotoxic drugs.
Standard hypercalcemia-related metabolic parameters, such as serum levels of calcium, phosphate, and magnesium, as well as serum creatinine, should be carefully monitored following initiation of therapy with zoledronic acid. If hypocalcemia, hypophosphatemia, or hypomagnesemia occur, short-term supplemental therapy may be necessary.
5.3 Renal Impairment
Zoledronic acid is excreted intact primarily via the kidney, and the risk of adverse reactions, in particular renal adverse reactions, may be greater in patients with impaired renal function. Safety and pharmacokinetic data are limited in patients with severe renal impairment and the risk of renal deterioration is increased [see Adverse Reactions (6.1)]. Preexisting renal insufficiency and multiple cycles of zoledronic acid and other bisphosphonates are risk factors for subsequent renal deterioration with zoledronic acid. Factors predisposing to renal deterioration, such as dehydration or the use of other nephrotoxic drugs, should be identified and managed, if possible.
Zoledronic acid treatment in patients with hypercalcemia of malignancy with severe renal impairment should be considered only after evaluating the risks and benefits of treatment [see Dosage and Administration (2.1)]. In the clinical studies, patients with serum creatinine greater than 400 µmol/L or greater than 4.5 mg/dL were excluded.
Zoledronic acid treatment is not recommended in patients with bone metastases with severe renal impairment. In the clinical studies, patients with serum creatinine greater than 265 µmol/L or greater than 3.0 mg/dL were excluded and there were only 8 of 564 patients treated with zoledronic acid 4 mg by 15-minute infusion with a baseline creatinine greater than 2 mg/dL. Limited pharmacokinetic data exists in patients with creatinine clearance less than 30 mL/min [see Clinical Pharmacology (12.3)].
5.4 Osteonecrosis of the Jaw
Osteonecrosis of the jaw (ONJ) has been reported predominantly in cancer patients treated with intravenous bisphosphonates, including zoledronic acid. Many of these patients were also receiving chemotherapy and corticosteroids which may be risk factors for ONJ. The risk of ONJ may increase with duration of exposure to bisphosphonates.
Postmarketing experience and the literature suggest a greater frequency of reports of ONJ based on tumor type (advanced breast cancer, multiple myeloma), and dental status (dental extraction, periodontal disease, local trauma including poorly fitting dentures). Many reports of ONJ involved patients with signs of local infection including osteomyelitis.
Cancer patients should maintain good oral hygiene and should have a dental examination with preventive dentistry prior to treatment with bisphosphonates.
While on treatment, these patients should avoid invasive dental procedures if possible. For patients who develop ONJ while on bisphosphonate therapy, dental surgery may exacerbate the condition. For patients requiring dental procedures, there are no data available to suggest whether discontinuation of bisphosphonate treatment reduces the risk of ONJ. Clinical judgment of the treating physician should guide the management plan of each patient based on individual benefit/risk assessment [see Adverse Reactions (6.2)].
5.5 Musculoskeletal Pain
In postmarketing experience, severe and occasionally incapacitating bone, joint, and/or muscle pain has been reported in patients taking bisphosphonates, including zoledronic acid. The time to onset of symptoms varied from one day to several months after starting the drug. Discontinue use if severe symptoms develop. Most patients had relief of symptoms after stopping. A subset had recurrence of symptoms when rechallenged with the same drug or another bisphosphonate [see Adverse Reactions (6.2)].
5.6 Atypical Subtrochanteric and Diaphyseal Femoral Fractures
Atypical subtrochanteric and diaphyseal femoral fractures have been reported in patients receiving bisphosphonate therapy, including zoledronic acid. These fractures can occur anywhere in the femoral shaft from just below the lesser trochanter to just above the supracondylar flare and are transverse or short oblique in orientation without evidence of comminution. These fractures occur after minimal or no trauma. Patients may experience thigh or groin pain weeks to months before presenting with a completed femoral fracture. Fractures are often bilateral; therefore the contralateral femur should be examined in bisphosphonate-treated patients who have sustained a femoral shaft fracture. Poor healing of these fractures has also been reported. A number of case reports noted that patients were also receiving treatment with glucocorticoids (such as prednisone or dexamethasone) at the time of fracture. Causality with bisphosphonate therapy has not been established.
Any patient with a history of bisphosphonate exposure who presents with thigh or groin pain in the absence of trauma should be suspected of having an atypical fracture and should be evaluated. Discontinuation of zoledronic acid therapy in patients suspected to have an atypical femur fracture should be considered pending evaluation of the patient, based on an individual benefit risk assessment. It is unknown whether the risk of atypical femur fracture continues after stopping therapy.
5.7 Patients With Asthma
While not observed in clinical trials with zoledronic acid, there have been reports of bronchoconstriction in aspirin-sensitive patients receiving bisphosphonates.
5.8 Hepatic Impairment
Only limited clinical data are available for use of zoledronic acid to treat hypercalcemia of malignancy in patients with hepatic insufficiency, and these data are not adequate to provide guidance on dosage selection or how to safely use zoledronic acid in these patients.
Hypocalcemia has been reported in patients treated with zoledronic acid injection. Cardiac arrhythmias and neurologic adverse events (seizures, tetany, and numbness) have been reported secondary to cases of severe hypocalcemia. In some instances, hypocalcemia may be life-threatening. Caution is advised when zoledronic acid injection is administered with drugs known to cause hypocalcemia, as severe hypocalcemia may develop, [see Drug Interactions (7)]. Serum calcium should be measured and hypocalcemia must be corrected before initiating zoledronic acid injection. Adequately supplement patients with calcium and vitamin D.