Intravenous Osteolytic bone metastases, Osteolytic lesions associated with multiple myeloma
Adult: 90 mg as a single infusion 3-4 wkly. Max infusion rate: 60 mg/hr. Elderly: Initiate at lower end of adult dosing range.
Intravenous Hypercalcaemia of malignancy
Adult: 15-90 mg (based on initial plasma Ca concentration) as a single infusion or in divided doses over 2-4 consecutive days. Plasma Ca levels generally start declining 24-48 hr after a dose w/ normalisation w/in 3-7 days; may repeat treatment if normocalcaemia is not achieved w/in this time or if hypercalcaemia recurs. Max infusion rate: 60 mg/hr. Elderly: Initiate at lower end of adult dosing range.
Intravenous Paget's disease of bone
Adult: 30 mg once wkly by infusion for 6 wk (total dose: 180 mg), alternatively, 30 mg in the 1st wk, then 3 doses of 60 mg every other wk (total dose: 210 mg); may repeat course 6 mthly (total dose may be increased up to 360 mg) when clinically indicated. Max infusion rate: 60 mg/hr. Elderly: Initiate at lower end of adult dosing range.
Renal Impairment
Max infusion rate: 20 mg/hr. Paget's disease of bone:
CrCl (mL/min)
Dosage
<30
Avoid.
Hypercalcaemia of malignancy:
CrCl (mL/min)
Dosage
<30
Avoid, unless in life-threatening cases.
Osteolytic lesions associated with multiple myeloma: Osteolytic bone metastases:
CrCl (mL/min)
Dosage
<30
If renal function deteriorates, withheld treatment until renal function returns to w/in 10% of the baseline value.
Reconstitution
Add 10 mL of sterile water for inj to a vial labelled as containing 30 mg or 90 mg to prepare a soln containing 3 mg or 9 mg per mL, respectively. Prior to infusion, dilute further w/ dextrose 5% or NaCl 0.45% or 0.9% to the desired concentration.
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.
Overdosage
Symptoms: Hypocalcaemia, high fever, hypotension, transient taste perversion. Management: Administer IV or oral Ca to treat hypocalcaemia; fever and hypotension may be corrected w/ steroids.
Drug 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).
Lab Interference
May interfere w/ diagnostic imaging agents (e.g. technetium-99m-diphosphonate) in bone scans.
Action
Description: 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. Onset: Hypercalcaemia of malignancy: ≤24 hr (for decrease in albumin-corrected serum Ca); Paget's disease: Approx 1 mth (for ≥50% decrease in serum alkaline phosphatase). Duration: Hypercalcaemia of malignancy: 7-14 days; Paget's disease: 1-372 days. Pharmacokinetics: Absorption: Poorly absorbed from the GI tract. Bioavailability: Approx 1-3%. Distribution: Crosses the placenta. Plasma protein binding: Approx 54%. Metabolism: Not metabolised. Excretion: Via urine, approx 20-55% as unchanged drug. Elimination half-life: 21-35 hr.
Chemical Structure
Pamidronic acid Source: National Center for Biotechnology Information. PubChem Database. Pamidronic acid, CID=4674, https://pubchem.ncbi.nlm.nih.gov/compound/Pamidronic-acid (accessed on Jan. 22, 2020)
Storage
Store between 20-25°C. Reconstituted soln: Store between 2-8°C, stable for 24 hr.
M05BA03 - pamidronic acid ; Belongs to the class of bisphosphonates. Used in the treatment of bone diseases.
References
Anon. Pamidronate. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 26/082015.Buckingham R (ed). Pamidronate. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 26/08/2015.McEvoy GK, Snow EK, Miller J et al (eds). Pamidronate Disodium. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 26/08/2015.Pamidronate Disodium Injection, Powder, Lyophilized, for Solution (Areva Pharmaceuticals Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 26/08/2015.
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