MajorNitrogen-containing bisphosphonate×Mineral supplements. Calcium
Updated · Methodology
Mechanism
Oral bioavailability of alendronic acid is minimal to begin with, and anything reaching the stomach at the same time wipes it out. The label says so plainly: food, drinks including mineral water, calcium supplements and antacids interfere with absorption. The paradox is that both are prescribed together for the same osteoporosis.
Symptoms
Densitometry that fails to improve after 12–24 months, or a new vertebral fracture while the bisphosphonate is running.
Management
Alendronate is taken on rising with a glass of tap water, and at least 30 minutes must pass before any other oral intake, calcium included, per the label. Do not lie down during that window because of oesophagitis risk. Calcium and vitamin D remain necessary in osteoporosis: move them to midday or dinner rather than stopping them.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.
Summary of a multi-drug list →
Medicine list: everything you take in one place →
Sources
- AEMPS: Ficha técnica Ácido alendrónico semanal Cinfamed 70 mg comprimidos EFG (2024)– AEMPS, CIMA, nº registro 70911, sección 4.5
- NIH Office of Dietary Supplements: Calcium – Health Professional Fact Sheet (2025)– NIH ODS, Calcium, Interactions with Medications