[The effect of a calcium carbonate-bismuth subsalicylate combination on intragastric acidity over the course of 24 hours. A randomized study of healthy probands].

Bismuth salts are successfully used for the treatment of campylobacter-pylori-associated gastritis. It cannot be excluded, however, that calcium carbonate, which is present in one of the recommended preparations (calcium carbonate/bismuth subsalicylate, Jatrox), may have an additional therapeutic effect due to an increase of intragastric pH. Therefore, the in-vitro H+ buffering capacity of Jatrox was determined in comparison to other antacids using the pH-stat technique, and its effect on intragastric acidity was tested in 15 healthy volunteers using ambulatory 24-hour pH-metry (combined glass electrode in gastric corpus, solid state memory recorder, sampling rate 30/min). At two study sessions, the volunteers received standardized normal meals (8:00 a.m., 12:00 noon, 6:00 p.m.) and, in randomized order, either Jatrox (three times 2 tablets one hour before meals) or no medication. Under in-vitro conditions, the buffering capacity of Jatrox amounts to 7.82 mmol H+ per tablet (equivalent to 47 mmol H+/24 h at recommended dosage), which is relatively low. Under in-vivo conditions, gastric pH only increases significantly during the first hour after medication. This short-lasting effect, however, has no influence on the 24-hour median pH. It is concluded from these results that the calcium carbonate contained in Jatrox probably does not contribute directly towards its therapeutic effect in promoting the healing of gastritis.