Pamidronate

Indications

Pamidronate is used for: Hypercalcemia of Malignancy, Paget's Disease, Osteolytic Bone Metastases of Breast Cancer, Osteolytic Bone Lesions of Multiple Myeloma

Adult Dose

Intravenous Hypercalcemia of Malignancy Moderate hypercalcemia (ie, corrected serum calcium 12-13.5 mg/dL): 60-90 mg single-dose IV infusion over 2-24 hours Severe hypercalcemia (ie, corrected serum calcium > 13.5 mg/dL): 90 mg single-dose IV infusion over 2-24 hours May repeat after at least 7 days in patients showing partial or complete response if serum calcium does not remain in normal range Paget's Disease 30 mg IV infused over 4 hours qDay for 3 consecutive days (ie, total cumulative dose 90 mg) Osteolytic Bone Metastases of Breast Cancer 90 mg IV infusion over 2 hours q3-4Weeks Osteolytic Bone Lesions of Multiple Myeloma 90 mg IV infusion over 4 hours qMonth

Child Dose

Safety & efficacy not established

Renal Dose

Renal impairment: Max infusion rate: 20 mg/hr. CrCl (ml/min) Dosage Recommendation <30 Avoid, unless in life-threatening cases.

Administration

IV Preparation Reconstitute by adding 10 mL of SWI to a vial May be further diluted in 250-1000 mL of 1/2NS, NS or D5W IV Administration Slowly infuse over 2-24 hours Longer infusion may reduce risk of nephrotoxicity

Contra Indications

Pregnancy, Hypersensitivity, Lactation.

Precautions

Patient w/ cardiac disease, previous thyroid surgery; pre-existing anaemia, leucopenia or thrombocytopenia. Renal impairment. Elderly. Pregnancy. Patient Counselling Rarely, this drug may cause somnolence and/or dizziness, if affected, do not drive or operate machinery. Maintain good oral hygiene and adequate hydration. Monitoring Parameters Monitor renal function; serum electrolytes, including Ca, phosphate, Mg and K; CBC w/ differential. Perform routine dental check up.

Pregnancy-Lactation

Interactions

Enhanced hypocalcaemic effect w/ aminoglycosides. Increased nephrotoxic effect w/ thalidomide. Enhanced adverse effects w/ NSAIDs. Synergistic effect w/ calcitonin in patients w/ severe hypercalcaemia. Concomitant use w/ other bisphosphonates, other antihypercalcaemic agents and calcitonin may lead to hypocalcaemia w/ associated clinical symptoms (e.g. paraesthesia, tetany, hypotension).

Adverse Effects

Side effects of Pamidronate : Renal toxicity, fever and flu-like symptoms, CNS effects (e.g. agitation, confusion, dizziness, lethargy, insomnia, somnolence), seizures, hallucinations, hypocalcaemia, hypophosphataemia, hypomagnesaemia, hypokalaemia, hypotension, HTN, anaemia, thrombocytopenia, lymphocytopenia; osteonecrosis of the jaw (cancer patient), femoral fractures (long term treatment). Rarely, hypernatraemia, hyperkalaemia, bronchospasm, interstitial pneumonitis.

Mechanism of Action

Pamidronic acid inhibits bone resorption and decreases mineralisation by suppressing the accession of osteoclast precursors onto the bone, thus preventing transformation into mature, absorbing osteoclasts.