Increased renal clearance & decreased effects of lithium, acidic drugs eg, chlorpropamide, salicylates, tetracyclines, barbiturates. Prolonged t
½ & increased effects or toxicity of basic drugs eg, amphetamines, ephedrine/pseudoephedrine. Reduced or increased rate &/or extent of absorption of drugs eg, antacids, laxative, other antibiotics. Systemic alkalosis & development of Ca stones w/ antacids. Increased Al absorption w/ Al-containing antacids. Reduced solubility of quinolones eg, ciprofloxacin, norfloxacin or ofloxacin. Reduced antibacterial effect of hexamine. Additive effect w/ laxatives.