Which medications should be spaced apart by 30-60 minutes due to absorption interactions with bisphosphonates?

• A. Calcium supplements, antacids, and iron supplements
• B. Vitamin C and vitamin E
• C. Antibiotics only
• D. Protein shakes

Answer: (A)

Bisphosphonates have limited oral absorption, and minerals in the gut can bind to them, forming insoluble complexes that the body cannot absorb. Calcium, iron, and certain antacids contain minerals that readily chelate with bisphosphonates, significantly reducing the drug’s uptake if they’re taken together. Spacing these minerals by 30–60 minutes allows the bisphosphonate to be absorbed first, preserving its effectiveness. Practically, you take the bisphosphonate with a full glass of water first thing in the morning and wait before consuming other medications or foods that contain calcium, iron, or aluminum. Vitamin C and vitamin E don’t have the same binding effect, and protein shakes vary in mineral content, but the well-established interaction to avoid at the same time is with calcium, iron, and antacids.