Drug Interaction Report

MONITOR: Coadministration of bisphosphonates and loop diuretics may potentiate the risk of hypocalcemia. Bisphosphonates alone often cause mild, asymptomatic hypocalcemia via inhibitive effects on bone resorption and possibly chelation of blood calcium. These effects may be additive with those of loop diuretics, which tend to increase the urinary excretion of calcium.

MANAGEMENT: Caution is advised if bisphosphonates are coadministered with loop diuretics. Renal function as well as serum calcium levels should be monitored during and after treatment, since the effects of bisphosphonates can continue for many weeks after discontinuation. Patients and clinicians should be alert to signs and symptoms of clinical hypocalcemia such as muscle spasm, carpopedal spasm, laryngeal spasm, tetany, convulsions, mental changes (irritability, depression, psychosis), increased intracranial pressure, papilledema, QT interval prolongation, and cardiac arrhythmias.

ADJUST DOSING INTERVAL: Food significantly decreases the bioavailability of risedronate, possibly to negligible levels.

MANAGEMENT: Risedronate should be administered with 180 to 240 mL (6 to 8 ounces) of plain water, at least 30 minutes before the first food, beverage, or medication of the day. Patients should remain upright for at least 30 minutes following administration of risedronate.