Decreased absorption of weakly acidic drugs eg, digoxin, phenytoin, chlorpromazine, INH, chlordiazepoxide, indomethacin, Fe salts. Increased absorption of weakly basic drugs eg, pseudoephedrine, l-dopa. Decreased tetracycline bioavailability. Inhibited quinidine, amphetamines excretion. Enhanced salicylates excretion.