Zoledronic acid

12.1 Mechanism of Action The principal pharmacologic action of zoledronic acid is inhibition of bone resorption. Although the antiresorptive mechanism is not completely understood, several factors are thought to contribute to this action. In vitro , zoledronic acid inhibits osteoclastic activity and induces osteoclast apoptosis. Zoledronic acid also blocks the osteoclastic resorption of mineralized bone and cartilage through its binding to bone. Zoledronic acid inhibits the increased osteoclastic activity and skeletal calcium release induced by various stimulatory factors released by tumors.

1 INDICATIONS AND USAGE Zoledronic acid injection is a bisphosphonate indicated for the treatment of: Hypercalcemia of malignancy. (1.1) Patients with multiple myeloma and patients with documented bone metastases from solid tumors, in conjunction with standard antineoplastic therapy. Prostate cancer should have progressed after treatment with at least one hormonal therapy. (1.2) Limitations of Use : The safety and efficacy of zoledronic acid injection has not been established for use in hyperparathyroidism or non-tumor-related hypercalcemia. 1.1 Hypercalcemia of Malignancy Zoledronic acid injection is indicated for the treatment of hypercalcemia of malignancy defined as an albumin-corrected calcium (cCa) of greater than or equal to 12 mg/dL [3.0 mmol/L] using the formula: cCa in mg/dL=Ca in mg/dL + 0.8 ( 4.0 g/dL - patient albumin [g/dL]). 1.2 Multiple Myeloma and Bone Metastases of Solid Tumors Zoledronic acid injection is indicated for the treatment of patients with multiple myeloma and patients with documented bone metastases from solid tumors, in conjunction with standard antineoplastic therapy. Prostate cancer should have progressed after treatment with at least one hormonal therapy. Limitations of Use The safety and efficacy of zoledronic acid injection in the treatment of hypercalcemia associated with hyperparathyroidism or with other non–tumor-related conditions have not been established.

2 DOSAGE AND ADMINISTRATION Hypercalcemia of malignancy ( 2.1 ) 4 mg as a single-use intravenous infusion over no less than 15 minutes. 4 mg as retreatment after a minimum of 7 days. Multiple myeloma and bone metastasis from solid tumors. ( 2.2 ) 4 mg as a single-use intravenous infusion over no less than 15 minutes every 3 to 4 weeks for patients with creatinine clearance of greater than 60 mL/min. Reduce the dose for patients with renal impairment. Coadminister oral calcium supplements of 500 mg and a multiple vitamin containing 400 international units of vitamin D daily. Administer through a separate vented infusion line and do not allow to come in contact with any calcium or divalent cation-containing solutions. ( 2.3 ) Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. 2.1 Hypercalcemia of Malignancy The maximum recommended dose of zoledronic acid injection in hypercalcemia of malignancy (albumin-corrected serum calcium greater than or equal to 12 mg/dL [3.0 mmol/L]) is 4 mg. The 4 mg dose must be given as a single-dose intravenous infusion over no less than 15 minutes . Patients who receive zoledronic acid injection should have serum creatinine assessed prior to each treatment. Dose adjustments of zoledronic acid injection are not necessary in treating patients for hypercalcemia of malignancy presenting with mild-to-moderate renal impairment prior to initiation of therapy (serum creatinine less than 400 µmol/L or less than 4.5 mg/dL). Patients should be adequately rehydrated prior to administration of zoledronic acid injection [ see Warnings and Precautions (5.2) ]. Consideration should be given to the severity of, as well as the symptoms of, tumor-induced hypercalcemia when considering use of zoledronic acid injection. Vigorous saline hydration, an integral part of hypercalcemia therapy, should be initiated promptly and an attempt should be made to restore the urine output to about 2 L/day throughout treatment. Mild or asymptomatic hypercalcemia may be treated with conservative measures (i.e., saline hydration, with or without loop diuretics). Patients should be hydrated adequately throughout the treatment, but overhydration, especially in those patients who have cardiac failure, must be avoided. Diuretic therapy should not be employed prior to correction of hypovolemia. Retreatment with zoledronic acid injection 4 mg may be considered if serum calcium does not return to normal or remain normal after initial treatment. It is recommended that a minimum of 7 days elapse before retreatment, to allow for full response to the initial dose. Renal function must be carefully monitored in all patients receiving zoledronic acid injection and serum creatinine must be assessed prior to retreatment with zoledronic acid injection [ see Warnings and Precautions (5.2) ]. 2.2 Multiple Myeloma and Bone Metastases of Solid Tumors The recommended dose of zoledronic acid injection in patients with multiple myeloma and metastatic bone lesions from solid tumors for patients with creatinine clearance (CrCl) greater than 60 mL/min is 4 mg infused over no less than 15 minutes every 3 to 4 weeks. The optimal duration of therapy is not known. Upon treatment initiation, the recommended zoledronic acid injection doses for patients with reduced renal function (mild and moderate renal impairment) are listed in Table 1. These doses are calculated to achieve the same area under the curve (AUC) as that achieved in patients with creatinine clearance of 75 mL/min. CrCl is calculated using the Cockcroft-Gault formula [ see Warnings and Precautions (5.2) ]. Table 1: Reduced Doses for Patients with Baseline CrCl Less Than or Equal to 60 mL/min * Doses calculated assuming target AUC of 0.66 (mg•hr/L) (CrCl=75 mL/min) Baseline Creatinine Clearance (mL/min) Zoledronic Acid Injection Recommended Dose (mg) * greater than 60 4 50 to 60 3.5 40 to 49 3.3 30 to 39 3 During treatment, serum creatinine should be measured before each zoledronic acid injection dose and treatment should be withheld for renal deterioration. In the clinical studies, renal deterioration was defined as follows: For patients with normal baseline creatinine, increase of 0.5 mg/dL For patients with abnormal baseline creatinine, increase of 1.0 mg/dL In the clinical studies, zoledronic acid injection treatment was resumed only when the creatinine returned to within 10% of the baseline value. Zoledronic acid injection should be reinitiated at the same dose as that prior to treatment interruption. Patients should also be administered an oral calcium supplement of 500 mg and a multiple vitamin containing 400 international units of vitamin D daily. 2.3 Preparation of Solution Zoledronic acid injection must not be mixed with calcium or other divalent cation-containing infusion solutions, such as Lactated Ringer's solution, and should be administered as a single intravenous so

6 ADVERSE REACTIONS The most common adverse events (greater than 25%) were nausea, fatigue, anemia, bone pain, constipation, fever, vomiting, and dyspnea ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Avet Pharmaceuticals Inc. at 1-866-901-DRUG (3784) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Hypercalcemia of Malignancy The safety of zoledronic acid injection was studied in 185 patients with hypercalcemia of malignancy (HCM) who received either zoledronic acid injection 4 mg given as a 5-minute intravenous infusion (n=86) or pamidronate 90 mg given as a 2-hour intravenous infusion (n=103). The population was aged 33 to 84 years, 60% male and 81% Caucasian, with breast, lung, head and neck, and renal cancer as the most common forms of malignancy. NOTE: pamidronate 90 mg was given as a 2-hour intravenous infusion. The relative safety of pamidronate 90 mg given as a 2-hour intravenous infusion compared to the same dose given as a 24-hour intravenous infusion has not been adequately studied in controlled clinical trials. Renal Toxicity Administration of zoledronic acid injection 4 mg given as a 5-minute intravenous infusion has been shown to result in an increased risk of renal toxicity, as measured by increases in serum creatinine, which can progress to renal failure. The incidence of renal toxicity and renal failure has been shown to be reduced when zoledronic acid injection 4 mg is given as a 15-minute intravenous infusion. Zoledronic acid injection should be administered by intravenous infusion over no less than 15 minutes [see Warnings and Precautions ( 5.3 ), Dosage and Administration ( 2.4 )]. The most frequently observed adverse events were fever, nausea, constipation, anemia, and dyspnea (see Table 4). Table 4 provides adverse events that were reported by 10% or more of the 189 patients treated with zoledronic acid injection 4 mg or pamidronate 90 mg from the two HCM trials. Adverse events are listed regardless of presumed causality to study drug. Table 4: Percentage of Patients with Adverse Events Greater Than or Equal to 10% Reported in Hypercalcemia of Malignancy Clinical Trials by Body System Zoledronic Acid Injection 4 mg n (%) Pamidronate 90 mg n (%) Patients Studied Total No. of Patients Studied 86 (100) 103 (100) Total No. of Patients with any AE 81 (94) 95 (92) Body as a Whole Fever 38 (44) 34 (33) Progression of Cancer 14 (16) 21 (20) Cardiovascular Hypotension 9 (11) 2 (2) Digestive Nausea 25 (29) 28 (27) Constipation 23 (27) 13 (13) Diarrhea 15 (17) 17 (17) Abdominal Pain 14 (16) 13 (13) Vomiting 12 (14) 17 (17) Anorexia 8 (9) 14 (14) Hemic and Lymphatic System Anemia 19 (22) 18 (18) Infections Moniliasis 10 (12) 4 (4) Laboratory Abnormalities Hypophosphatemia 11 (13) 2 (2) Hypokalemia 10 (12) 16 (16) Hypomagnesemia 9 (11) 5 (5) Musculoskeletal Skeletal Pain 10 (12) 10 (10) Nervous Insomnia 13 (15) 10 (10) Anxiety 12 (14) 8 (8) Confusion 11 (13) 13 (13) Agitation 11 (13) 8 (8) Respiratory Dyspnea 19 (22) 20 (19) Coughing 10 (12) 12 (12) Urogenital Urinary Tract Infection 12 (14) 15 (15) The following adverse events from the two controlled multicenter HCM trials (n=189) were reported by a greater percentage of patients treated with zoledronic acid injection 4 mg than with pamidronate 90 mg and occurred with a frequency of greater than or equal to 5% but less than 10%. Adverse events are listed regardless of presumed causality to study drug: asthenia, chest pain, leg edema, mucositis, dysphagia, granulocytopenia, thrombocytopenia, pancytopenia, nonspecific infection, hypocalcemia, dehydration, arthralgias, headache and somnolence. Rare cases of rash, pruritus, and chest pain have been reported following treatment with zoledronic acid injection. Acute Phase Reaction Within three days after zoledronic acid injection administration, an acute phase reaction has been reported in patients, with symptoms including pyrexia, fatigue, bone pain and/or arthralgias, myalgias, chills, and influenza-like illness. These symptoms usually resolve within a few days. Pyrexia has been the most commonly associated symptom, occurring in 44% of patients. Mineral and Electrolyte Abnormalities Electrolyte abnormalities, most commonly hypocalcemia, hypophosphatemia, and hypomagnesemia, can occur with bisphosphonate use. Grade 3 and Grade 4 laboratory abnormalities for serum creatinine, serum calcium, serum phosphorus, and serum magnesium observed in two clinical trials of zoledronic acid injection in patients with HCM are shown in Table 5 and 6. Table 5: Grade 3 Laboratory Abnormalities for Serum Creatinine, Serum Calcium, Serum Phosphorus, and Serum Magnesium in Two Clinical Trials in Patients with HCM Laborato

7 DRUG INTERACTIONS Aminoglycosides: May have an additive effect to lower serum calcium for prolonged periods. ( 7.1 ) Loop Diuretics: Concomitant use with zoledronic acid injection may increase risk of hypocalcemia. ( 7.2 ) Nephrotoxic Drugs: Use with caution. ( 7.3 ) In vitro studies indicate that the plasma protein binding of zoledronic acid is low, with the unbound fraction ranging from 60% to 77%. In vitro studies also indicate that zoledronic acid does not inhibit microsomal CYP450 enzymes. In vivo studies showed that zoledronic acid is not metabolized, and is excreted into the urine as the intact drug. 7.1 Aminoglycosides and Calcitonin Caution is advised when bisphosphonates are administered with aminoglycosides or calcitonin, since these agents may have an additive effect to lower serum calcium level for prolonged periods. This effect has not been reported in zoledronic acid injection clinical trials. 7.2 Loop Diuretics Caution should also be exercised when zoledronic acid injection is used in combination with loop diuretics due to an increased risk of hypocalcemia. 7.3 Nephrotoxic Drugs Caution is indicated when zoledronic acid injection is used with other potentially nephrotoxic drugs. 7.4 Thalidomide No dose adjustment for zoledronic acid injection 4 mg is needed when coadministered with thalidomide. In a pharmacokinetic study of 24 patients with multiple myeloma, zoledronic acid injection 4 mg given as a 15 - minute infusion was administered either alone or with thalidomide (100 mg once daily on days 1 to 14 and 200 mg once daily on Days 15 to 28). Coadministration of thalidomide with zoledronic acid injection did not significantly change the pharmacokinetics of zoledronic acid or creatinine clearance.