Calcium Bioavailability from Two Calcium Carbonate Preparations

Publisher Website
Google Scholar
Abstract
Calcium carbonate is the preferred calcium supplement because calcium absorption from this salt is as good as that from milk and other calcium salts,1 it is the least expensive form,2 and its lower molecular weight allows the use of a smaller pill.1 However, several preparations of calcium carbonate are available commercially, and because of their various rates of disintegration in vitro and dissolution characteristics, it has been suggested that calcium absorption from different preparations can vary widely.3 We studied two calcium carbonate preparations — Caltrate 600 (preparation A; lot number, 5510–1102; Lederle Laboratories, Pearl River, N.Y.) and Calcium 600 (preparation B; lot number, 578702; Rugby Laboratories, Rockville Center, N.Y.). We selected these two products because according to the U.S. Pharmacopeia (USP) method of in vitro dissolution, preparation A was 97 percent dissolved in 30 minutes, and preparation B was less than 5 percent dissolved (Shangraw RF: personal communication); therefore, the former met the USP standard of at least 75 percent dissolution in 30 minutes, whereas the latter did not. We studied the in vitro dissolution of each preparation in dilute acid under different stirring conditions. As shown in Figure 1 , preparation A always dissolved faster than preparation B; however, the rapidity of dissolution and the magnitude of the difference between the two preparations depended on the method of stirring. Which if any of these stirring conditions simulate those in the gastrointestinal tract is not known.

This publication has 3 references indexed in Scilit: