Absorption and metabolism of oral zinc gluconate in humans in fasting state, during, and after a meal.

The absorption and metabolism of zinc in a commercial form for oral use (Rubozinc, 15 mg zinc as gluconate) were investigated in 10 subjects by a kinetic study of the serum zinc profile after administration of 45 mg zinc under three conditions: after an overnight fast, during a standardized breakfast, and 2 h after this meal. The pharmacokinetic parameters were calculated by a method suitable to the characterization of rebound effects (recycling of the element in the gastrointestinal tract). In fasting state, the parameters were comparable to those previously collected in the same subjects with oral 45 mg zinc as sulfate, except with very significantly higher Cmax and area under curve (AUC), showing a better bioavailability for zinc in the commercial form. The light meal perturbed the absorption process as evidenced by the significant increases in the lag time (+180%), the tmax (+57%), and the lag times for the first two cycles during the meal. However, the parameters returned to normal values 2 h after the meal. The Cmax only moderately decreased during the meal (31%) as did the AUC (-28%). An important delay in the absorption of zinc in the commercial form when taken during a meal was therefore demonstrated, but the effect on zinc bioavailability was only moderate.