Bisphosphonate prodrugs

Bisphosphonates (BP) are pyrophosphate analogs having a P-C-P backbone. The oral bioavailability of BPs is ca. 1%, due to high ionisation at physiological pH. Using the prodrug approach, oral absorption can be increased by masking one or more ionizable groups (clodronate, etidronate), or using a targeting carrier system (alendronate, pamitronate).