Effect of intermittent therapy with a slow‐release fluoride preparation

Long‐term clinical effects of intermittent sodium fluoride (slow‐release) therapy were assessed in 71 patients with primary osteoporosis. In Group I (receiving 1,25‐(OH)₂D₃ 2 μg/day for 2 weeks before 3 months of sodium fluoride treatment 25 mg twice a day, in each 5‐month cycle), vertebral (L2‐L4) bone mineral content did not change significantly. However, the L2‐L4 bone mineral content significantly increased by 3.1% in Group II (those who did not receive 1,25‐(OH)₂D₃ during 5‐month cycle), 3.5% per patient year in Group III (combined NaF 25 mg twice a day with 1,25‐(OH)₂D₃ 0.5 μg/day for 12 months in each 13‐month cycle), and by 7.8% per patient year in Group IV (combined NaF with calcium citrate for 12 months in each 13‐month cycle). The rise in vertebral bone mineral content was sustained, with an annual increment of 4.2% during the third year compared with 4.4% during the first year. The vertebral fracture rate declined significantly from the pretreatment value in all groups, but comparison with a placebo control group was not available. There was no significant change in the bone density of the radial shaft or of the proximal femur. The rate of hip fracture (nontraumatic) during treatment was 1.8% per patient year, the same as before treatment. The drug was well tolerated with only minor infrequent gastrointestinal and rheumatic side effects. Thus, intermittent slow‐release sodium fluoride treatment with adequate calcium supplementation augments spinal bone mass and apparently inhibits vertebral fractures, with a satisfactory safety of usage; however, it has no effect on appendicular bone mass or on hip fracture rate. The vertebral fracture rate declined significantly in all groups, suggesting that fluoride may reduce vertebral fractures. However, comparison with a placebo control group was not available.