Effects of antacids on gastrointestinal absorption of drugs.

Antacids interfere with gastrointestinal drug absorption by either increasing or decreasing the rate at which a drug is absorbed, or the total quantity absorbed. Antacids influence drug absorption by alteration of ionization state or solubility, factors dependent upon pH. Antacids also delay gastric emptying and are capable of chelation and adsorption with susceptible products. Many of these factors participate to produce the effect on gastrointestinal drug absorption in individual patients.