Which bisphosphonate is given as an example for hypercalcemia?

• A. Pamidronate
• B. Alendronate
• C. Risedronate
• D. Zoledronic acid

Answer: (A)

This item tests how bisphosphonates lower calcium by stopping bone resorption. Nitrogen-containing bisphosphonates inhibit farnesyl pyrophosphate synthase in the mevalonate pathway, which deactivates and even kills osteoclasts. With osteoclast activity suppressed, bone breakdown slows and calcium released into the blood decreases.

In hypercalcemia, especially related to malignancy, you need a rapid reduction of serum calcium. An intravenous bisphosphonate is preferred because it acts quickly to curb bone resorption. Pamidronate fits this role well: it’s given IV and can lower calcium levels within one to two days, making it a common and reliable choice for hypercalcemia of malignancy.

Other options like the oral bisphosphonates alendronate and risedronate are designed for osteoporosis and are not suitable for acute hypercalcemia due to slower onset and issues with oral absorption. Zoledronic acid is another IV bisphosphonate and is even more potent, and it’s also used for hypercalcemia, but pamidronate is the classic example often cited for this indication.