[Antacids: A comparison of their in vitro neutralizing capacity in hydrochloric acid and in acidified peptone solution (author's transl)].

Using a simple and reproducible in vitro-test the neutralizing capacity of different liquid commercial antacids was measured at pH 2.0 and at pH 3.5 in diluted hydrochloric acid and in acidified peptone solution. In peptone solutions corresponding to postprandial gastric juice, antacids containing aluminum hydroxide and aluminate forming components demonstrated a marked loss in their neutralizing capacity when compared to peptone free hydrochloric acid as control. This loss in buffering capacity is dependent on the reaction time, the pH of the reaction mixture, the concentration of peptone in the solution and the amount of aluminum in the different antacid compounds. Furthermore the neutralizing capacity of aluminum hydroxide is also diminished by dibasic organic acids which mimicked fasting gastric juice in the experiment. The different availability of neutralizing potency of aluminum hydroxide containing antacids in acid and in acidified peptone solution will need to be considered when antacids are recommended for the treatment of patients with peptic ulcer disease.