Bioavailability and pharmacokinetics of fluoride from two glutamine monofluorophosphate preparations

A two-way cross-over study was conducted on 12 Caucasian male healthy volunteers aged between 25 and 38 years in order to determine the bioavailability and pharmacokinetics of fluoride after single oral administration in fasting conditions of two products (tablets and powder for oral use) of L-glutamine monofluorophosphate (G-MFP, CAS 116420-36-1). The two products contained the equivalent of 10 mg F and the equivalent of 300 mg CA as calcium gluconate and calcium citrate. The two products were found bioequivalent with regard to the release of fluoride, both on the basis of the AUC and Cmax of fluoride in plasma and of the urinary excretion of fluoride during the 48 h following the administration. The pharmacokinetics of fluoride in plasma is characterized by a short lag time (< 6 min), a rapid absorption, a peak which is reached 0.5-1.0 h after administration, followed by a biphasic elimination. The first phase with a k alpha of 1.8 h-1 is followed by a slower phase with a K beta of 0.14 h-1. Probably the terminal elimination rate is slower, about 0.05 h-1. The urinary excretion of fluoride during the 48 h after administration accounted for 40-50% of the administered dose of fluoride. The results are consistent with those found in previous studies after administration in fasting conditions of sodium fluoride or sodium monofluorophosphate alone or in combination with calcium salts.