FURTHER ANALYSIS OF STANDARDS FOR ANTACID SIMETHICONE DEFOAMING PROPERTIES

The testing standards for the measurement of the defoaming properties of antacid simethicone tablets as outlined in the U.S. Pharmacopeia XX III were assessed. Three standards have been designed for three differ ent formulations of antacid simethicone tablets. Each standard is inte nded for use in assessing a different antacid simethicone formulation: (1) alumina, magnesia, and simethicone tablets; (2) alumina, magnesia , calcium carbonate, and simethicone tablets; and (3) magaldrate and s imethicone tablets. In this study, the commercially available antacid simethicone tablets and one tablet that is not available commercially were tested using all three methods. The results obtained with the fir st method listed revealed that Riopan Plus(R) failed to meet the estab lished criterion for defoaming activity time. Using the second method, the following products did not meet the criterion: Gelusil(R), Maalox (R), Thrifty(R), and Riopan Plus(R). When the third method was used al l products demonstrated complete and instantaneous defoaming activity. These results raise the question as to why specific tests were devise d for specific antacid simethicone tablets. A single test should be us ed for all preparations, thus allowing a direct comparison of their in vitro activity.