Which bisphosphonate has the highest relative potency listed and is typically given intravenously?

Which bisphosphonate has the highest relative potency listed and is typically given intravenously?

• A. Etidronate
• B. Zolendronate
• C. Pamidronate
• D. Alendronate

Answer: (B)

Potency and how a drug is given are tightly linked for bisphosphonates. Zoledronic acid is the strongest member of the common nitrogen-containing bisphosphonates, meaning it has the greatest antiresorptive effect on osteoclasts. It is given by IV infusion because these drugs have very low oral bioavailability, so delivering them intravenously ensures a reliable, rapid, and potent exposure. This combination of highest potency and intravenous administration is why zoledronic acid is the correct choice. By contrast, etidronate is older and less potent and is usually taken by mouth; pamidronate is IV but less potent than zoledronic acid; alendronate is potent but mainly oral.

Potency and how a drug is given are tightly linked for bisphosphonates. Zoledronic acid is the strongest member of the common nitrogen-containing bisphosphonates, meaning it has the greatest antiresorptive effect on osteoclasts. It is given by IV infusion because these drugs have very low oral bioavailability, so delivering them intravenously ensures a reliable, rapid, and potent exposure. This combination of highest potency and intravenous administration is why zoledronic acid is the correct choice. By contrast, etidronate is older and less potent and is usually taken by mouth; pamidronate is IV but less potent than zoledronic acid; alendronate is potent but mainly oral.