A 70-year-old woman with osteoporosis (T-score −2.8) sustains a vertebral compression fracture. She is currently on alendronate. Lab shows elevated serum alkaline phosphatase. Which drug from the bisphosphonate class has the highest potency (relative antiresorptive activity) and is administered as a once-yearly infusion?
- A Alendronate
- B Zoledronic acid (zoledronate) ✓
- C Risedronate
- D Etidronate
Explanation
Zoledronic acid (Zometa/Aclasta) is the most potent nitrogen-containing bisphosphonate, given as a single annual IV infusion of 5 mg. It inhibits farnesyl pyrophosphate synthase in the mevalonate pathway, disrupting osteoclast function and survival. It is indicated for osteoporosis, Paget's disease (single 5 mg dose), bone metastases, and hypercalcemia of malignancy. Alendronate and risedronate are oral weekly bisphosphonates of lower potency. Etidronate is a first-generation non-nitrogen bisphosphonate, significantly less potent. The annual infusion improves compliance compared to daily/weekly oral regimens.
Reference: Maheshwari Essential Orthopaedics, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.