Zoledronic Acid

Uses

Zoledronic Acid is used for:

• Hypercalcaemia of malignancy,
• Bone metastases associated with solid tumours, Osteolytic lesions associated with multiple myeloma,
• Corticosteroid-induced osteoporosis, Increase bone mass in men with osteoporosis, Osteoporosis in postmenopausal women
• Paget's disease of bone
• Prophylaxis of postmenopausal osteoporosis

Zoledronic Acid is also used to associated treatment for these conditions: Bone Metastases, Hypercalcemia of Malignancy, Multiple Myeloma (MM), Osteoporosis, Osteoporosis caused by Glucocorticoid Treatment, Osteoporosis caused by glucocorticoid, Paget's Disease of Bone, Paget’s Disease, Bone Mineral Density

How Zoledronic Acid works

Bisphosphonates are taken into the bone where they bind to hydroxyapatite. Bone resorption by osteoclasts causes local acidification, releasing the bisphosphonate, which is taken into the osteoclast by fluid-phase endocytosis. Endocytic vesicles become acidified, releasing bisphosphonates into the cytosol of osteoclasts where they act.

Osteoclasts mediate resorption of bone. When osteoclasts bind to bone they form podosomes, ring structures of F-actin. Etidronic acid also inhibits V-ATPases in the osteoclast, though the exact subunits are unknown, preventing F-actin from forming podosomes. Disruption of the podosomes causes osteoclasts to detach from bones, preventing bone resorption.

Nitrogen containing bisphosphonates such as zoledronate are known to induce apoptosis of hematopoietic tumor cells by inhibiting the components of the mevalonate pathway farnesyl diphosphate synthase, farnesyl diphosphate, and geranylgeranyl diphosphate. These components are essential for post-translational prenylation of GTP-binding proteins like Rap1. The lack of prenylation of these proteins interferes with their function, and in the case of Rap1, leads to apoptosis. zoledronate also activated caspases which further contribute to apoptosis.

Dosage

Zoledronic Acid dosage

Hypercalcemia of malignancy: The maximum recommended dose of Zoledronic Acid in hypercalcemia of malignancy (serum calcium 12 mg/dl or 3.0 mmol/l) is 4 mg. The 4 mg dose must be given as a single-dose intravenous infusion. Dose adjustment of Zoledronic Acid is not necessary in treating patients for hypercalcemia of malignancy presenting with mild-to-moderate renal impairment. Re-treatment with Zoledronic Acid may be considered if serum calcium does not return to normal after initial treatment. It is recommended that a minimum of 7 days elapse before re-treatment, to allow for full response to the initial dose.Multiple myeloma and bone metastases of solid tumors: The recommended dose of Zoledronic Acid in patients with multiple myeloma and metastatic bone lesions from solid tumors is 4 mg infused every 3-4 weeks. Patients should also be administered an oral calcium supplement of 500 mg and 400 IU of Vitamin-D daily.

Prior to administration, the required amount of concentrate from one vial must be further diluted with 100 ml of calcium-free infusion solution (0.9% w/v sodium chloride solution or 5% w/v glucose solution). The duration of infusion must not be less than 15 minutes. After addition of the solution to the infusion media, the infusion solution should be used as soon as possible. If storage of the infusion solution is necessary, hold at 2-8º C for not more than 24 hours. If refrigerated, the solution must be allowed to reach room temperature before administration.Zoledronic Acid 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 solution in a line separate from all other drugs.

Side Effects

The post-dose side-effects are headache, nausea, anorexia, fatigue, osteonecrosis of jaw, anemia, bone pain, constipation, fever, vomiting, flu-like syndrome, hypocalcemia, myalgia, arthralgia and hypophosphataemia.

Toxicity

Patients experiencing an overdose may present with renal impairment, hypocalcemia, hypophosphatemia, and hypomagnesemia. Overdose should be managed through intravenous administration of the insufficient ions.

Precaution

Patients must be appropriately hydrated prior to administration of Zoledronic Acid. This is especially important in the elderly and for patients receiving diuretic therapy. Adequate hydration can be achieved by the patient drinking two glasses of fluid (such as water) before and after the infusion. Serum levels of calcium, phosphate, magnesium and potassium, as well as serum creatinine should be carefully monitored after initiating Zoledronic Acid therapy. If hypocalcemia, hypophosphatemia or hypomagnesemia occurs, short-term supplemental therapy may be necessary. Moreover, careful renal function monitoring should be considered.

Interaction

In clinical studies, Zoledronic Acid has been administered concomitantly with commonly used anticancer agents, diuretics, antibiotics and analgesics without interactions. Caution is advised when Zoledronic Acid are administered with aminoglycosides, since these agents may have an additive effect to lower serum calcium level for prolonged periods. In multiple myeloma patients, the risk of renal dysfunction may be increased when Zoledronic Acid is used in combination with thalidomide. Concomitant use of loop diuretics with Zoledronic Acid increases the risk of hypocalcemia. Caution is indicated when Zoledronic Acid is used with other potentially nephrotoxic drugs.

Food Interaction

Elimination Route

A 4mg intravenous dose reaches a C_max of 370±78.5ng/mL, with a T_max of 0.317±0.014h, and an AUC of 788±181ng*h/mL. A 5mg intravenous dose reaches a C_max of 471±76.1ng/mL, with a T_max of 0.368±0.005h, and an AUC of 917±226ng*h/mL.

Half Life

Zoledronic Acid has a terminal elimination half life of 146 hours.

Clearance

Zoledronic Acid has a renal clearance of 3.7 ± 2.0 L/h.

Elimination Route

Zoledronic Acid is 39 ± 16% eliminated in the urine as the unmetabolized parent drug.

Pregnancy & Breastfeeding use

Zoledronic Acid is contraindicated during pregnancy and in breast-feeding women. It is also not recommended for use in children and adolescents below 18 years of age.

Contraindication

The drug is contraindicated if patients have hypersensitivity to the active substance or to any of the excipients or to any bisphosphonates; severe renal impairment (Creatinine clearance <30 ml/min); pregnancy and lactation.

Special Warning

Patients with renal impairment: The use of Zoledronic Acid is not recommended in patients with severe renal impairment (Creatinine clearance <30 ml/min). No dose adjustment is necessary in patients with creatinine clearance >60 ml/min. Based on creatinine clearance the following dose should be used in patient with impaired renal function:

• CrCl > 60 ml/min: 4 mg (5 ml)
• CrCl 50-60 ml/min: 3.5 mg (4.4 ml)
• CrCl 40-49 ml/min: 3.3 mg (4.1 ml)
• CrCl 30-39 ml/min: 3 mg (3.8 ml)

Acute Overdose

Clinical experience with acute over dosage is limited. Over dosage may cause hypocalcemia, hypophosphatemia, and hypomagnesemia. In such case, reduction in serum levels of calcium, phosphorus, and magnesium should be corrected by intravenous administration of calcium gluconate, potassium or sodium phosphate and magnesium sulfate respectively.

Storage Condition

Store below 30° C prior to opening. Protect from moisture and light. Zoledronic Acid must be kept out of the reach and sight of children.

Innovators Monograph

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