Fluoride pharmacokinetics: its implications in the fluoride treatment of osteoporosis

This report reviews some aspects of fluoride pharmacokinetics in relation to the treatment of osteoporosis. The bioavailability of conventional plain NaF tablets has been shown to be close to 100, for sustained-release NaF tablets close to 90%, and for enteric-coated NaF tablets 65%. The simultaneous intake of food and/or calcium tablets reduces the bioavailability by 30 to 40%. Fluoride renal clearance is influenced by both urinary pH and flow and the clinical consequences of this is discussed. Studies on plasma kinetics of fluoride during chronic fluoride intake suggests that a plasma sample taken at mid-dosage intervals will give reproducible "mean steady-state" levels. It is suggested that improvements of the clinical benefit of fluoride therapy in osteoporosis might be achieved if the dosage regimen were based on the pharmacokinetic properties of the fluoride preparation used as well as plasma fluoride monitoring.