Gallium nitrate

Dose-dependent direct proximal renal tubular injury (acute tubular necrosis). Gallium behaves as a trivalent iron mimetic; after IV administration it is cleared renally and accumulates in the renal cortex, where uptake into proximal tubular epithelium produces tubular-cell injury and a rise in serum creatinine and BUN. The injury is markedly potentiated by volume depletion (a prerenal/ischemic second hit) and by concurrently administered nephrotoxins such as aminoglycosides and amphotericin B. The near-universal asymptomatic hypophosphatemia seen with treatment is generally attributed to gallium's effects on renal phosphate handling rather than to glomerular injury.

Typically an asymptomatic, non-oliguric rise in serum creatinine and BUN detected on daily labs during the 5-day infusion. It is frequently accompanied by asymptomatic hypophosphatemia (up to ~97% of patients in the registrational hypercalcemia trial) and, as the intended therapeutic effect, a falling serum calcium. Overt uremic symptoms are uncommon at approved antihypercalcemic doses, but azotemia can be pronounced at the higher doses used for antineoplastic effect.

Discontinue gallium nitrate at the first significant rise in serum creatinine (and do not resume until renal function recovers). Restore and maintain intravenous volume, hold co-administered nephrotoxins, and provide supportive care; the ATN is usually reversible once the drug is stopped and the patient is rehydrated. Repair the accompanying electrolyte disturbances — replete phosphate (hypophosphatemia is very common) and watch for hypocalcemia and hypomagnesemia. There is no specific antidote.Lesion-level management framework

A threshold contraindication rather than a graded reduction: do not initiate if serum creatinine is above ~2.5 mg/dL, and discontinue therapy if creatinine rises to ~2.5 mg/dL (or shows a significant increase) during treatment. Ensure the patient is well hydrated with adequate urine output before and throughout the 5-day course, and give by slow continuous IV infusion. No validated dosing exists for dialysis-dependent patients.

Not well characterized. Gallium circulates largely bound to transferrin and plasma proteins and redistributes into bone with a long terminal elimination, so it is not expected to be efficiently cleared by conventional hemodialysis, and there is no established role for dialysis in managing its toxicity. Data are limited — treat as probably not meaningfully dialyzable.

Severe hypercalcemia itself impairs renal function (nephrogenic diabetes insipidus with volume depletion causing prerenal azotemia, plus chronic hypercalcemic nephropathy), so drug-induced ATN must be distinguished from the AKI the patient may already have. Also consider the other nephrotoxins commonly co-administered in these patients (aminoglycosides, amphotericin B, IV contrast, cisplatin/ifosfamide), plicamycin (mithramycin) nephrotoxicity, tumor lysis syndrome, and obstructive or myeloma-related renal disease from the underlying malignancy.