PANTOPRAZOLE AND 2 4 H O U R INTRAGASTRIC ACIDITY SIRS, In their recent publication, Hannan et al. discuss the efficacy of pantoprazole 40 and 60 mg in comparison to H,-antagonists and omeprazole 20 mg.’ The authors conclude that doses of 40 and 60mg pantoprazole ‘appear to produce a change in acidity intermediate between that produced by standard doses of H,-antagonists and omeprazole 20 mg’. This is quite surprising as Sharma et al.,’ cited by Hannan and coworkers as reference for the efficacy of 20 mg omeprazole, reported a 90% inhibition of intragastric acidity with 20 mg omeprazole. Based on the results of their own study,’ however, more than 99 % inhibition can be calculated for 60 mg pantoprazole (placebo pH = 1.4-that is, H+ activity = 39.8 mmol/L; 60 mg pH = 3.5-that is, H+ activity = 0.3 mmol/L). In particular, the conclusion of Hannan et al. seems to be based on the statement ‘Sharma and co-workers, however, found that omeprazole 20mg raised 24-h gastric pH in duodenal ulcer subjects to a median of 5 . 3 , and Prichard et al. reported a median pH of 5.0’. First of all, it should be mentioned that in the study performed by Prichard et aL3 40 mg and not 2 0 mg omperazole were administered. In addition, Sharma et al.’ reported a 90% inhibition of acidity with 20 mg omeprazole, which corresponds to an increase of 1 pH unit. As the control pH was 1.4, this results in a pH of 2.4 and not 5.0 as stated (probably a typing error) in the discussion by Sharma et al. Even with 30 mg omeprazole only a pH of approximately 3 can be calculated. These pH values can be verified based on the reported acidity data by use of logarithmic transformation. It is noteworthy that a pH of 2.4, as calculated above for 20 mg omeprazole, is in the range of our own findings. In a two-period crossover, double-blind, randomized study in 1 6 healthy volunteers, the effect of 40 mg pantoprazole p.0. once daily for 7 days on intragastric pH was investigated vs. 20 mg omeprazole p.0. once daily. On Day 7 of this intra-individual comparison, which is more reliable than the between-study comparison performed by Hannan et al., 40 mg pantoprazole was significantly more effective than 20 mg omeprazole. The median 24-h pH (68%-range) was 3.15 (1.90, 3.80) with pantoprazole and 2.05 (1.40, 3.30) with omeprazole. Median placebo pH was 1.2 in both period^.^ We conclude that 40 mg pantoprazole is more effective than 20 mg omeprazole with regard to 24-h intragastric pH. Hence, from a pharmacodynamic point of view, the most appropriate clinical dose of pantoprazole has been established as 40 mg. M . H A R T M A N N , H . B L I E S A T H , R . L ~ ~ H M A N N & W . WURST Depts of Clinical Research and Biometry Byk Gulden Pharmaceuticals, Byk-Gulden-Str. 2 7750 Konstanz, Germany