Intermittent bisphosphonate therapy in postmenopausal osteoporosis: progress to date.

Bisphosphonates are the most widely prescribed drugs in osteoporosis today. They have unequivocally shown their ability to reduce fracture rate at the spine (alendronic acid, risedronic acid, ibandronic acid) and at the hip (alendronic acid and risedronic acid). However, their dosage and administration procedures and the adverse reactions induced by their oral intake are responsible for low adherence. Therefore, intermittent regimens have been developed. Weekly alendronic acid and risedronic acid provide similar benefits, in terms of bone mineral density (BMD) and changes in biochemical markers, as those seen with their daily formulations. Ibandronic acid has been shown to reduce vertebral fractures when given intermittently. Ibandronic acid given orally monthly and intravenously every 2 or 3 months provides increases in BMD similar to the daily formulation. Yearly intravenous infusions of zoledronic acid are currently being evaluated for their ability to reduce fractures. If the efficacy and safety of bisphosphonates given at administration intervals longer than weekly are confirmed, this might significantly improve patient adherence and long-term outcomes of bisphosphonate treatment in postmenopausal osteoporosis.