FLUORIDE PHARMACOKINETICS AND CHANGES IN LUMBAR SPINE AND HIP BONE-MINERAL DENSITY

Debate about the use of fluoride for the treatment of vertebral osteop orosis has centered not only on whether fluoride treatment decreases v ertebral fractures, but also the interindividual vertebral bone minera l density (BMD) response, the potential for nonvertebral fractures, as well as side effects and tolerability. These effects may be dose depe ndent and, in this study, we examine the pharmacokinetics of sodium mo nofluorophosphate (MFP) in osteoporotic patients and relate this to ch anges in BMD, Plasma fluoride absorption curves were measured from 0 t o 6 h after ingestion of MFP at baseline and during long-term dosing i n 21 patients with vertebral osteoporosis (T scores less than or equal to 2), BMD was measured at baseline and at 12 months at the lumbar sp ine (LS), femoral neck (FN), trochanter, and Ward's triangle, We found that fluoride elimination was inversely related to creatinine clearan ce, LS BMD increased from a median of 0.77 g/cm(2) (range 0.69 to 0.99 ) at baseline to 0.88 g/cm(2) (0.75 to 1.13) (p < 0.001) after 12 mont hs, This equates to a median increase of 12% (range -1.2 to 37), Media n femoral neck BMD decreased from 0.75 g/cm(2) (0.62 to 0.94) at basel ine to 0.69 g/cm(2) (0.62 to 0.92) (p = 0.13) after 12 months, This eq uates to a decrease of -2% (-19 to 10), BMD at the other hip sites als o decreased slightly, Changes in LS and FN BMD were not significantly related (r = 0.28, p = 0.29), The various pharmacokinetic parameters m easured were not related to changes in LS BMD; however, there was an i nverse relationship between trough fluoride concentration during long- term dosing and change in FN BMD, Further studies are required to see if this relationship can be used to monitor osteoporotic patients trea ted with fluoride and prevent significant decreases in FN BMD and poss ibly fractures at this site. (C) 1996 by Elsevier Science Inc.