Pharmacokinetic differences between sodium fluoride and sodium monofluorophosphate and comparative bone mass increasing activity of both compounds in the rat.

After the administration of an oral dose of 80 mumol/l of NaF (CAS 7681-49-4) to rats, the area under the curve of total plasma fluoride equals 10,200 mumol.min/l. After an oral dose of 80 mumol of monofluorophosphate (MFP/CAS 10,163-15-2), two forms of fluoride appear in plasma: protein-bound MFP and diffusible fluoride. The areas under the curve of total (protein-bound + diffusible) and diffusible fluoride equal 22,200 and 8,850 mumol.min/l, respectively. The activity of MFP for increasing the bone mass of the rat was assessed with NaF as the standard. The animals were treated chronically for 100 days since weaning with food ad libitum and 5 mmol/l NaF, 5 or 2.5 mmol/l MFP solutions as the water supply. The effect obtained with 2.5 mmol/l MFP was similar to that produced by 5 mmol/l NaF, indicating a potency ratio MFP is twice as active as NaF.