Adverse effects of bisphosphonates: current issues

Four bisphosphonates are used for the treatment of metastatic bone disease: clodronate, which is available outside the United States in both intravenous and oral formulations; intravenous pamidronate; intravenous zoledronic acid; and ibandronate, which is also available in intravenous and oral forms. Since the use of bisphosphonates in patients with cancer is palliative, their impact on patients' quality of life and their adverse-effect profiles are essential considerations for effective patient management. The most common adverse effects associated with bisphosphonates are renal toxicity, acute-phase reactions, gastrointestinal (GI) toxicity, and osteonecrosis of the jaw (ONJ). The incidence of these adverse events varies significantly between bisphosphonates. Renal toxicity is a potentially life-threatening event reported in studies of zoledronic acid and, to a lesser extent, pamidronate. In contrast, the renal safety profile of intravenous ibandronate and oral bisphosphonates is similar to that of placebo. Acute-phase reactions occur only with intravenous aminobisphosphonates and may be more common with zoledronic acid. Gastrointestinal effects occur only with oral agents (clodronate and ibandronate) and may be avoided by adhering to dosing instructions. More recently, ONJ has recently emerged as a complication of bisphosphonate use. However, its true incidence is not yet known. The potential adverse effects of bisphosphonates should be considered in the context of the individual patient's characteristics and preferences when selecting a bisphosphonate for metastatic bone disease.