Characterization of antacid compounds containing both aluminum and magnesium. II. Codried powders.

The composition and antacid properties of six samples of codried antacids containing both aluminum and magnesium were determined. Aluminum hydroxide-magnesium carbonate codried gel and aluminum hydroxide-magnesium hydroxide codried gel were non-homogeneous, as the samples contained combinations of hydrotalcite, amorphous aluminum hydroxide, magnesium hydroxide, magnesium hydroxycarbonate, and magnesium carbonate. All samples passed the preliminary antacid test and had high acid neutralizing capacities. However, the rate of acid neutralization varied between samples. In some cases the rate of acid neutralization at a dose of 400 mg was too slow to raise the pH to 3.0 as required by the Rossett-Rice test.