Drug Interactions between Actonel with Calcium and lanthanum carbonate

ADJUST DOSING INTERVAL: Products containing aluminum, calcium, magnesium and other polyvalent cations such as antacids or vitamin with mineral supplements are likely to interfere with the gastrointestinal absorption of oral bisphosphonates. For example, the bioavailability of tiludronate has been shown to decrease 80% during simultaneous administration with calcium, and 60% when aluminum- or magnesium-containing antacids were administered one hour before tiludronate.

MANAGEMENT: Antacids or other oral medications containing aluminum, calcium, magnesium and other polyvalent cations should be administered at least 30 minutes after the bisphosphonate dose.

ADJUST DOSING INTERVAL: Theoretically, lanthanum carbonate may chelate with certain drugs in the gastrointestinal tract, resulting in reduced oral bioavailability of those drugs during coadministration. However, an in vitro study involving digoxin, enalapril, furosemide, metoprolol, phenytoin, and warfarin found no evidence that lanthanum carbonate forms insoluble complexes with these drugs in simulated gastric fluid. Studies in healthy subjects have also found no effect of lanthanum carbonate (1000 mg for 4 doses) on the absorption of a single dose of digoxin (0.5 mg), metoprolol (100 mg), or warfarin (10 mg).

MANAGEMENT: To minimize the potential for interaction, drugs that are known to interact with antacids (e.g., ACE inhibitors, beta blockers, bisphosphonates, coumarin derivatives, digitalis glycosides, fluoroquinolones, iron, phenytoin, rifampin, tetracyclines, thyroid preparations) should not be taken within 2 hours of administration of lanthanum carbonate according to the product labeling.