Pamidronate is a nitrogen-containing bisphosphonate used in oncology to reduce and prevent skeletal complications from cancer and to treat malignancy-related hypercalcemia.
Pharmacological Class
- Bisphosphonate (anti-resorptive agent)
- Second-generation, nitrogen-containing
Mechanism of Action
- Binds to bone hydroxyapatite, particularly at active resorption sites.
- Inhibits farnesyl pyrophosphate synthase in the mevalonate pathway in osteoclasts → disrupts osteoclast cytoskeleton → apoptosis → decreased bone resorption.
Oncology Indications
- Hypercalcemia of malignancy
- Bone metastases from breast cancer, prostate cancer, lung cancer, etc.
- Multiple myeloma with lytic bone lesions
Oncology Dosing (Adults)
| Indication | Dose | Infusion Duration |
|---|---|---|
| Hypercalcemia of malignancy | 60–90 mg IV once | ≥2 hours |
| Bone metastases (breast cancer, myeloma) | 90 mg IV every 3–4 weeks | 2–4 hours |
Renal adjustment:
Avoid rapid infusion — nephrotoxic risk ↑
Reduce dose or extend infusion time in renal impairment (CrCl <60 mL/min)
Administration Notes
- IV infusion only — never IV push
- Dilute in 250–500 mL NS or D5W
- Infuse over ≥2 hours (often 4 hours for myeloma) to minimize renal toxicity
- Ensure patient is well-hydrated before infusion
Adverse Effects
Common:
- Acute phase reaction (fever, myalgia, arthralgia within 48 hours — more common after first dose)
- Nausea, fatigue
Serious:
- Hypocalcemia, hypophosphatemia, hypomagnesemia (monitor and correct before therapy)
- Renal toxicity (dose-dependent; avoid rapid infusion)
- Osteonecrosis of the jaw (ONJ) — risk increases with prolonged use and invasive dental procedures
- Rare: atypical femoral fractures
Oncology Pharmacist Considerations
- Check serum creatinine and electrolytes before each dose
- Delay treatment if hypocalcemia or uncontrolled electrolyte abnormalities
- Dental exam before starting to lower ONJ risk
- Continue calcium (500–1,000 mg/day) and vitamin D (400–800 IU/day) supplementation unless contraindicated
- Pamidronate has slower onset for hypercalcemia than zoledronic acid but is often better tolerated renally in moderate CKD