Gastric tolerance of single dose unbuffered and buffered acetylsalicylic acid: a randomized comparative endoscopic study in 24 volunteers.

A randomized, three-way crossover study by gastroscopic examination in 24 healthy male volunteers was performed to compare the gastric tolerance of a single dose of buffered or unbuffered acetylsalicylic acid. Gastroscopic assessment was made two hours after administration of the buffered (800 mg ASA) or unbuffered (500 mg ASA) tablets taken with 200 ml of water. Mucosal changes were rare and of a minor nature. Only two volunteers in the unbuffered ASA group presented minor changes (erythema and oedema). No pathological changes were observed after the buffered ASA. Subjective adverse reactions, e.g. epigastric complaints, were reported by four volunteers in the unbuffered group and by two in the buffered group. Based on the limited number and the minor extent of visible changes, statistical tests did not appear to be warranted. The results indicate that buffered ASA is better tolerated.