The oral absorption of
bisphosphonates is significantly reduced (90% reduction with clodronate) by aluminium/magnesium hydroxide and other
antacids.
Bisphosphonates should be prevented from coming into contact with
antacids (containing aluminium, bismuth, calcium, magnesium). Recommendations on
the timing of
administration of
bisphosphonates in relation to food and other drugs varies. Alendronate and risedronate should be taken at least 30 minutes before taking the first food or drink of the day, clodronate should probably be taken at least 1 hour before or after antacids, ibandronate should be taken 1 hour before antacids, and etidronate and tiludronate should be taken at least 2 hours apart from
antacids.