Prevention and management of osteoporosis: consensus statements from the Scientific Advisory Board of the Osteoporosis Society of Canada. 7. Fluoride therapy for osteoporosis.

OBJECTIVE: To present the latest findings on the use of fluoride in the treatment of osteoporosis. OPTIONS: Plain sodium fluoride (NaF), enteric-coated sodium fluoride (EC-NaF), sodium monofluorophosphate (Na2FPO4), slow-release sodium fluoride (SR-NaF); fluoride with a calcium supplement. OUTCOMES: Fracture and loss of bone mineral density in osteoporosis; increased bone mass, prevention of fractures and improved quality of life associated with treatment. EVIDENCE: Relevant clinical studies and reports were examined, with an emphasis on recent prospective, randomized, controlled trials. Clinical practices in European countries were also considered. VALUES: Reducing fractures, increasing bone mineral density and minimizing side effects of treatment were given a high value. BENEFITS, HARMS AND COSTS: NaF therapy stimulates bone formation and may be effective in preventing osteoporotic fractures. It may be an acceptable alternative treatment to estrogen or bisphosphonate therapy and useful in premenopausal and corticosteroid-induced osteoporosis and in some patients with mild osteogenesis imperfecta. Toxic effects are dependent on formulation and dosage. They include a range of gastrointestinal and musculoskeletal conditions. EC-NaF is associated with less toxicity than plain NaF; its gastrointestinal toxicity is negligible. Na2FPO4 has no gastrointestinal toxicity, but can give rise to skeletal toxicity. SR-NaF appears to have no side effects when given intermittently. Carcinogenicity has not been found in vivo with fluoride therapy, despite in vitro results. RECOMMENDATIONS: New data indicate that fluoride therapy should be re-evaluated as a potentially effective treatment of osteoporosis with minimal side effects. More studies are needed of slow-release fluoride formulations, intermittent treatment schedules and calcium supplementation of fluoride. Studies should be undertaken to see if it is advantageous to initiate treatment with antiresorptive agents before or in combination with fluoride. Conclusive data have not been presented regarding the benefit of any specific type of calcium supplement. Further studies on the basic mechanism of action of fluoride on the skeleton are necessary to evaluate fluoride's potential to stimulate bone formation therapeutically.