bisphosphonate
3 interactions related to bisphosphonate
risedronate + calcium
Calcium and other divalent cations bind risedronate in the gut and form insoluble complexes, blocking absorption of a drug whose oral bioavailability is already very low (~0.6%). Co-administration can reduce the dose to subtherapeutic levels.
alendronate + coffee
Studies cited in the FDA label show coffee (and orange juice) reduce alendronate bioavailability by approximately 60%. Given the drug's already minuscule baseline absorption of ~0.6%, this drop can render the dose therapeutically ineffective.
alendronate + calcium
Calcium binds alendronate in the gut and forms an insoluble chelate, drastically reducing absorption of an already poorly bioavailable bisphosphonate (oral bioavailability is only ~0.6%). Co-administration can render the osteoporosis drug clinically ineffective.