Pamidronate
**Pamidronate** is a bisphosphonate medication primarily used in veterinary medicine for the management of **hypercalcaemia**, particularly when associated with vitamin D toxicosis (e.g., cholecalciferol rodenticide ingestion) or hypercalcaemia of malignancy. > **Clinical Warning:** Pamidronate can cause renal toxicity and is contraindicated in patients with pre-existing renal dysfunction. Adequate hydration is essential during administration. **Clinical Pearl:** In addition to treating hypercalcaemia, pamidronate is frequently utilized as an adjunctive analgesic to manage pain associated with malignant osteolysis and bone tumours (such as osteosarcoma) in dogs.
Mechanism: Pamidronate binds strongly to hydroxyapatite crystals in the bone matrix. It **inhibits osteoclast activity** and **induces osteoclast apoptosis** → decreases bone resorption → lowers serum calcium concentrations and reduces osteolytic bone destruction and associated pain.
Dosing by species
- Hypercalcaemia / Bone tumour pain · 0.65-2 mg/kg (typically 1 mg/kg) slow infusion with NaCl 0.9% over 2-4 hours · IV · q28days if required · As needed · Some clinicians advocate 0.9% NaCl i.v. for 2 hours before and after the infusion.
- Cholecalciferol-induced toxicosis · 0.65-2 mg/kg (typically 1 mg/kg) slow infusion with NaCl 0.9% over 2-4 hours · IV · On days 1 and 4 post-ingestion · 2 doses · Some clinicians advocate 0.9% NaCl i.v. for 2 hours before and after the infusion.
- Hypercalcaemia · 1.0-2.0 mg/kg slow (over 4 hours) infusion · IV · Single dose · Over 4 hours
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
Contraindications
- Renal dysfunction
Adverse effects
- Renal toxicity
- Nausea
- Diarrhoea
- Hypocalcaemia
- Hypophosphataemia
- Hypomagnesaemia
- Hypersensitivity reactions
- Ophthalmic syndromes (reported in humans)
- Bone pain (reported in humans)
- Electrolyte abnormalities (reported in humans)
- Blood dyscrasias (reported in humans)
Drug interactions
- Aminoglycosides · Concurrent use may result in severe hypocalcaemia · major
- NSAIDs · Increased risk of renal toxicity; use with caution · moderate
Monitoring
- Serum calcium (ionized and total)
- Serum phosphorus
- Serum magnesium
- Renal function panel (BUN, Creatinine, USG)
- Hydration status
Overdose
Overdosage may lead to severe **hypocalcaemia**, **hypophosphataemia**, and **hypomagnesaemia**, as well as acute renal failure. Treatment is supportive, including intravenous fluids and electrolyte supplementation (e.g., calcium gluconate) as dictated by serum monitoring.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.