7 DRUG INTERACTIONS
No in vivo drug interaction studies have been performed for zoledronic acid. In vitro and ex vivo studies showed low affinity of zoledronic acid for the cellular components of human blood. In vitro mean zoledronic acid protein binding in human plasma ranged from 28% at 200 ng/mL to 53% at 50 ng/mL. In vivo studies showed that zoledronic acid is not metabolized, and is excreted into the urine as the intact drug.
Caution is advised when bisphosphonates, including zoledronic acid, are administered with aminoglycosides, since these agents may have an additive effect to lower serum calcium level for prolonged periods. This effect has not been reported in zoledronic acid clinical trials.
7.2 Loop Diuretics
Caution should also be exercised when zoledronic acid is used in combination with loop diuretics due to an increased risk of hypocalcemia.
7.3 Nephrotoxic Drugs
Caution is indicated when zoledronic acid is used with other potentially nephrotoxic drugs such as nonsteroidal anti-inflammatory drugs.
7.4 Drugs Primarily Excreted by the Kidney
Renal impairment has been observed following the administration of zoledronic acid in patients with pre-existing renal compromise or other risk factors [see Warnings and Precautions (5.3)]. In patients with renal impairment, the exposure to concomitant medications that are primarily renally excreted (e.g., digoxin) may increase. Consider monitoring serum creatinine in patients at risk for renal impairment who are taking concomitant medications that are primarily excreted by the kidney.