Absorption Characteristics of Novel Compound Calcium Carbonate Granules: Effects of Gastric Acid Deficiency and Exogenous Weak Acids.

Calcium carbonates are commonly administered as supplements for conditions of calcium deficiency. We report here pharmacokinetic characteristics of a novel formulation, calcium carbonate compound granules (CCCGs), forming complexes of calcium carbonate and calcium citrate in water. CCCGs were compared to a kind of commonly-used calcium carbonate D3 preparation (CC) in the market in 5-week-old mice that had been treated with omeprazole, to suppress gastric acid secretion, and in untreated control mice. The results showed that: (1) CCCGs had better water solubility than CC in vitro; (2) In control mice, calcium absorption rates after CCCGs administration were comparable to those after CC administration; (3) Inhibition of gastric acid secretion did not affect calcium absorption after CCCGs, but moderately decreased it after CC; (4) The presence of phytic acid or tannin did not affect calcium absorption rates after CCCGs but did for CC; and (5) In normal mice, CCCGs did not inhibit gastric emptying and intestinal propulsion, and did not alter the gastrointestinal hormones. The results suggest that CCCGs may be therapeutically advantageous over more commonly used calcium supplement formulations, particularly for adolescents, because of their stable calcium absorption characteristics and their relatively favorable adverse effect profile.