Once-yearly administered intravenous zoledronic acid for postmenopausal osteoporosis.

OBJECTIVE: To review studies that investigated the use of once-yearly administered intravenous zoledronic acid for the treatment of postmenopausal osteoporosis.

DATA SOURCES: Searches of MEDLINE (1966-February 2008) and EMBASE (1974-February 2008) were conducted using the terms zoledronic acid, once-yearly, and postmenopausal osteoporosis. Literature review was limited to human studies.

STUDY SELECTION AND DATA EXTRACTION: All literature identified from the data sources was evaluated for review inclusion. Studies investigating the use of zoledronic acid in conditions other than postmenopausal osteoporosis, including malignant hypercalcemia, multiple myeloma, and Paget's disease, were excluded. Five randomized controlled studies were included in this review.

DATA SYNTHESIS: Oral bisphosphonates represent one of the most commonly prescribed drug classes for the treatment of postmenopausal osteoporosis. However, due to poor gastrointestinal absorption and poor patient adherence to bisphosphonate therapy, once-yearly intravenous zoledronic acid may be a more attractive option for some patients. Once-yearly zoledronic acid has been shown to decrease bone turnover markers such as serum C-telopeptide by 49-52%, decrease the vertebral fracture rate by approximately 70%, and significantly increase bone mineral density at total hip, femoral neck, and lumbar spine by 6.02%, 5.06%, and 6.71%, respectively. Furthermore, some women may prefer the convenience of once-yearly intravenous zoledronic acid to daily or weekly oral bisphosphonates. In clinical trials that compared once-yearly zoledronic acid infusion with weekly oral alendronate, participants preferred zoledronic acid and found its adverse effect profile to be more favorable.

CONCLUSIONS: Based on available evidence, once-yearly zoledronic acid is an efficacious treatment option for postmenopausal women with osteoporosis. However, lack of head-to-head studies with oral bisphosphonates is a limitation in evaluating its clinical utility. Additional studies investigating zoledronic acid against oral bisphosphonates, specifically looking at rates and types of fractures, are needed to fully determine its place in postmenopausal osteoporosis treatment.