[Metabolic effects of antacids and interactions with other drugs].

The incidence of side effects from antacids is low, but patients with renal insufficiency are at risk to develop alkalosis with high doses of calcium carbonate or magnesium hydroxides, or to develop hypercalcemia due to insufficient calcium elimination by the kidneys.--A great potential exists for drug interactions with antacids. In most instances, the effectiveness of other drugs is decreased in the presence of antacids, but effectiveness may be increased for L-dopa (less degradation in stomach) or quinidine (renal elimination reduced). Interactions at the absorption level can be avoided by administering the antacid one hour after intake of the other drugs (one hour after meals) which is also the optimum dosing schedule to ensure good antacid effect. Interactions through changes of urine pH are not eliminated by observing special dosing time schedules, but by modifying the dose or by selecting alternative drug treatment.