Studies on the in vitro interaction of D-penicillamine with antacids

Interactions of D-penicillamine with various antacids (aluminum hydroxide-magnesium hydroxide, AH-MH; aluminum hydroxide-calcium carbonate, AH-CC; dihydroxy sodium aluminum carbonate, DSAC; aluminum hydroxide, AH) were studied in vitro. Only a small binding to AH-MH (29.2 +/- 7.2 mumol/g antacid) and AH (13.6 +/- 4.0 mumol/g antacid) and no adsorption at all to AH-CC and DSAC were observed. Bile salts and bicarbonate as well as the pH did not influence binding. Although extrapolations from in vitro studies to in vivo conditions are hazardous, clinically relevant interactions of D-penicillamine with antacids in patients ingesting both drugs in the usual dose range simultaneously appear unlikely.