Zoledronic Acid [For osteoporosis]

Indications

Zoledronic Acid is indicated for the treatment of osteoporosis in postmenopausal women to reduce the incidence of hip, vertebral and non-vertebral fractures; prevention of clinical fractures after a hip fracture; treatment and prevention of glucocorticoid-induced osteoporosis; treatment of osteoporosis in men and for the treatment of paget's disease of bone. Treatment should be restricted to three annual doses.

Pharmacology

Zoledronic acid belongs to the class of nitrogen-containing bisphosphonates and acts primarily on bone. It is an inhibitor of osteoclast-mediated bone resorption. The action of bisphosphonates on bone is based on their high affinity for mineralized bone. Intravenously administered Zoledronic acid is rapidly distributed to bone. The main molecular target of Zoledronic acid in the osteoclast is the enzyme farnesyl pyrophosphate synthase, but this does not exclude other mechanisms. There was no accumulation of the active substance in plasma after multiple doses given every 28 days. Zoledronic acid is not metabolized and is excreted unchanged via the kidney.

Dosage

Treatment of postmenopausal osteoporosis: Recommended dose is a single intravenous infusion of 5 mg Zoledronic Acid administered once a year. Adequate supplemental Calcium and Vitamin-D intake is important in women with osteoporosis if dietary intake is inadequate. 

Prevention of clinical fractures after a hip fracture: Recommended dose is a single intravenous infusion of 5 mg Zoledronic Acid administered once a year. In patients with a recent low-trauma hip fracture, it is recommended to give the first Zoledronic Acid solution for infusion two or more weeks after hip fracture repairs. It is also recommended to have a loading dose of 50,000 to 125,000 IU of Vitamin-D given orally or via intramuscular route prior to the first administration of Zoledronic Acid solution for infusion. Supplemental Calcium and Vitamin-D intake is recommended for patients treated to prevent clinical fractures after a hip fracture.

Treatment of osteoporosis in men: Recommended dose is a single intravenous infusion of 5 mg Zoledronic Acid administered once a year. Adequate supplemental Calcium and Vitamin-D intake is important in men with osteoporosis if dietary intake is inadequate. 

Treatment and prevention of glucocorticoid-induced osteoporosis: Recommended dose is a single intravenous infusion of 5 mg Zoledronic Acid administered once a year. Adequate supplemental Calcium and Vitamin-D intake is important in patients with osteoporosis if dietary intake is inadequate.

Treatment of paget's disease of bone: Recommended dose is a single intravenous infusion of 5 mg Zoledronic Acid. Re-treatment with Zoledronic Acid may be considered in patients who have relapsed, based on increases in serum alkaline phosphatase, in patients who failed to achieve normalization of serum alkaline phosphatase, or in patients with symptoms, as dictated by medical practice 12 months after the initial dose.

In patients with paget's disease, adequate Vitamin-D intake is recommended in association with Zoledronic Acid administration. In addition, it is strongly advised that adequate supplemental Calcium corresponding to at least 500 mg elemental Calcium twice daily is ensured in patients with paget's disease for at least 10 days following Zoledronic Acid administration.

Administration

The dose of 5 mg Zoledronic acid must be administered over at least 15 minutes. Zoledronic Acid should be administered intravenously via a infusion line, given at a constant infusion rate. The infusion time must not be less than 15 minutes.

Interaction

Specific drug-drug interaction studies have not been conducted with Zoledronic acid. Zoledronic acid is eliminated by renal excretion. Caution is indicated when Zoledronic Acid is administered in conjunction with drugs that can significantly impact renal function (e.g. aminoglycosides or diuretics that may cause dehydration).

Contraindications

The drug is contraindicated if patients have hypersensitivity to the active substance or to any of the excipients or to any bisphosphonates, hypocalcaemia, renal impairment (creatinine clearance <35 mL/min), current or recent uveitis, or a history of bisphosphonate-associated uveitis, pregnancy and lactation.

Side Effects

The post-dose side-effects are fever, myalgia, flu-like symptoms, arthralgia and headache, the majority of which occur within the first 3 days following Zoledronic Acid administration. The majority of these symptoms were mild to moderate in nature and resolved within 3 days of the event onset. The incidence of these symptoms occurring within the first 3 days after administration of Zoledronic Acid, can be reduced with the administration of Paracetamol or Ibuprofen shortly following Zoledronic Acid administration. Severe and occasionally incapacitating bone, joint, and/or muscle pain have been infrequently reported in patients taking Zoledronic Acid.

Pregnancy & Lactation

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.

Precautions & Warnings

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. Pre-existing hypocalcaemia must be treated by adequate intake of Calcium and Vitamin-D before initiating therapy with Zoledronic Acid. Other disturbances of mineral metabolism must also be effectively treated (e.g. diminished parathyroid reserve, thyroid surgery, parathyroid surgery, intestinal Calcium malabsorption). Physicians should consider clinical monitoring for these patients.

Use in Special Populations

Patients with renal impairment: The use of Zoledronic Acid in patients with creatinine clearance <35 mL/min is not recommended due to limited clinical safety data in such patients. No dose adjustment is necessary in patients with creatinine clearance >35 mL/min.

Patients with hepatic impairment: No dose adjustment is required for patients with hepatic impairment.

Elderly patients: No dose adjustment is required. However, because decreased renal function occurs more commonly in the elderly, special care should be taken to monitor renal function.

Zoledronic Acid must not be mixed or given intravenously with any other medication and must be given through a separate infusion line at a constant infusion rate. If refrigerated, allow the refrigerated solution to reach room temperature before administration. Aseptic techniques must be followed during the preparation of the infusion. Any unused solution should be discarded. Only clear solution free from particles and discoloration should be used.

After opening, the solution is chemically and physically stable for at least 24 hours at 2°C to 8°C. From a microbiological point of view, the product should be used immediately. Zoledronic Acid solution for infusion must not be allowed to come into contact with any Calcium or other divalent cation-containing solutions.

Overdose Effects

Clinical experience with acute over dosage is limited. Patients who have received doses higher than those recommended should be carefully monitored. In the event of overdose leading to clinically significant hypocalcaemia, reversal may be achieved with supplemental oral Calcium and/or an infusion of Calcium.

Therapeutic Class

Bisphosphonate preparations

Storage Conditions

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.