In vivo andin vitro evaluation of magnesium-aluminum hydroxide antacid tablets and liquid

The effect of magnesium-aluminum hydroxide antacid tablets or liquid on food-stimulated gastric acidity was evaluatedin vivo in eight duodenal ulcer patients. Experiments were performed alsoin vitro. Althoughin vitro neutralizing capabilities of the two preparations were the same (28.3±0.1 mmol/liter), the duration of effect of tablets was longerin vivo. For example, at 3³/₄ hr after an eaten meal, mean hydrogen ion concentration with three tablets was 29.8±9.9 mmol/liter while with 15 ml liquid it was 59.6±10.3 mmol/liter (P <0.05). Additional studies were performedin vitro to explain the longer duration of effect of tablets compared with liquidin vivo. These experiments suggested that tablets reacted more slowly with acid than did liquid and that saliva, which was mixed with tablets during chewing, also contributed to the prolonged duration of effect.