We monitored 24-hour gastric acidity in 16 resistant duodenal ulcer patients treated with ranitidine 300 mg hora somni (9 cases) and famotidine 40 mg hora somni (7 cases) for 3 months. Data obtained in these patients were compared with those of a group of unselected duodenal ulcer patients who responded to a 4-week course of the same H2-antagonist regimens. In the time window 22.00-07.59 h there was a reduced effectiveness of ranitidine in nonresponder patients in terms of both mean pH levels (4.8 ± 0.9 vs. 5.6 ± 0.7, p <0.04) and the mean duration of the antisecretory effect defined as the time spent in minutes above pH 3.0 (403 ± 73 vs. 490 ± 59, p <0.02). Also, the action of famotidine was diminished in nonresponder patients in the same time interval as regards both pH values (4.1 ± 1.6 vs. 5.7 ± 0.6, p <0.03) and the duration in minutes (329 ± 163 vs. 473 ± 45, p <0.05). The analysis of all individual nonresponder patients shows that there was a certain variability in the duration of acid suppression: The majority of them had an adequate nocturnal acid inhibition, while in some cases of both the ranitidine and the famotidine subgroups, acid inhibition lasted only few hours or did not occur at all. At present, it is not possible to distinguish with certainty two different subsets of H2-antagonist nonresponders because of the small size of the population studied. A defective receptor binding or the development of tolerance may be implicated when the pharmacological effect of H2-receptor antagonists is too short.
- Duodenal ulcer
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