The effect of citrate, maltolate and fluoride on oral 26 Al absorption

Abstract

Aluminum (Al) has been suggested to contribute to dialysis encephalopathy, an osteomalacia, an anemia and Alzheimer's disease. The objectives were to investigate 1) the absolute oral bioavailability of 4 representative chemical species of Al, at an Al concentration between that produced by drinking water and antacid/phosphate binder use, and comparable ligand concentration, 2) whether the ligand has an influence on Al bioavailability, Tmax, and Cmax, and 3) whether the Al was absorbed as the Al complex. Male Fisher rats were orally administrated ~ 1 nCi 26Al (65 μM; 1750 μg/l) as the ion, or as a 1:1, 1:3 or 1:4 complex with 14C-citrate (Cit), 14 C–maltolate (Malt), or fluoride (F), respectively, during concurrent 27Al i.v. infusion. Blood samples were collected up to 24 h. Serum 26Al and 14C were quantified by accelerator mass spectrometry; 27Al by atomic absorption spectroscopy. Results were analyzed using WinNonlin and expressed as mean ± SD. None of the differences in the 3 endpoints was statistically significant among the Al species. The 14C concentration was ~100 times higher than expected if the 14C was absorbed as the Al complex, suggesting considerable dissociation of Al Cit and Al Malt in the GI tract. The within subject-time course of serum 26Al and 14C overlapped, suggesting that the Al might be absorbed as the Cit and Malt. The presence of Cit, Malt and F at the Al concentration and Al:ligand ratios studied had only a small effect on Al absorption. Funded by EPA STAR Grant 829783