[Binding of bile salts and lysolecithin by various antacids in biological media]

The in vitro capacity of several commercial antacids to bind bile acids and lysolecithin was measured in three different test media: 0.1 n HCl, natural human gastric juice and human gastric juice enriched with 5% protein. Antacids bind bile salts variably. In HCl and in natural and protein-enriched gastric juice the capacity to bind conjugated bile salts was higher (47-72%) for antacids with high aluminium content, such as Alucol, Andursil, Muthesa than for antacids with less aluminium such as Calamox and Riopan (17-18%). Binding of unconjugated bile salts did not show any corresponding difference. The test medium had little effect on binding capacity when pH was comparable. Natural gastric juice was slightly better with regard to binding of conjugated bile salts. The addition of protein had only minimal effect. Lysolecithin was equally heavily adsorbed by all tested antacids and in all three test conditions (85-100%). Since duodenogastral reflux contains mainly unconjugated bile salts, our results suggest that antacids with higher aluminium content should be preferred if binding of bile salt reflux is attempted.