Discovery, Clinical Development, and Therapeutic Uses of Bisphosphonates

Abstract

OBJECTIVE: To review the literature concerning the history, development, and therapeutic uses of bisphosphonates. DATA SOURCES: English-language articles were identified through a search of MEDLINE (through December 2004) using the key word bisphosphonate. Reference lists of pivotal studies, reviews, and full prescribing information for the approved agents were also examined. STUDY SELECTION AND DATA EXTRACTION: Selected studies included those that discussed the discovery and initial applications of bisphosphonates, as well as their historical development, pharmacokinetic and pharmacodynamic properties, and current therapeutic uses. DATA SYNTHESIS: Bisphosphonates structurally resemble pyrophosphates (naturally occurring polyphosphates) and have demonstrated similar physicochemical effects to pyrophosphates. In addition, bisphosphonates reduce bone turnover and resist hydrolysis when administered orally. The information gained from initial work with etidronate generated a considerable scientific effort to design new and more effective bisphosphonates. The PCP moiety in the general bisphosphonate structure is essential for binding to hydroxyapatite and allows for a number of chemical variations by changing the 2 lateral side chains (designated R1 and R2). The R1 side chain determines binding affinity to hydroxyapatite, and the R2 side chain determines antiresorptive potency. Accordingly, each bisphosphonate has its own characteristic profile of activity. CONCLUSIONS: The bisphosphonates reduce bone turnover, increase bone mass, and decrease fracture risk and therefore have a significant place in the management of skeletal disorders including osteoporosis, Paget's disease, bone metastases, osteogenesis imperfecta, and heterotopic ossification.