Impact of long-term ranitidine and pantoprazole on accuracy of [13C]urea breath test.

No previous study has analyzed the impact of long-term antisecretory drugs on the precision of [13C]urea breath test (UBT). We assessed the rate of UBT conversion from positive to negative results during 60-day therapy with standard doses of ranitidine and pantoprazole. For this purpose, we recruited 60 dyspeptic patients with H. pylori infection ascertained on the basis of the concomitant results of CLO-test, histology, and UBT. Our patients were randomly assigned to receive ranitidine 300 mg at night or pantoprazole 40 mg in the morning for 60 days. UBT was performed at baseline and on days 14, 30, and 60, while patients were still taking antisecretory drugs. Patients with false-negative UBT on day 60 repeated the test every 3 days until conversion. After overnight fasting, duplicate breath test samples were taken from each patient before and 30 min after ingestion of 75 mg [13C]urea dissolved in 150 ml of 0.033 mol/liter citric acid. Four patients dropped out of the study. Both drugs induced similar false-negative UBTs on day 14 of dosing (P = 0.5). Afterwards, the three false-negative UBTs in the ranitidine group again became positive during therapy and particularly on day 30 of dosing. Of the four false-negative UBTs in the pantoprazole group at day 60, one became positive after 3 and three after 9 days of therapy cessation. Our findings show that the long-term use of ranitidine and pantoprazole at standard doses has different effects on the results of UBT. In the pantoprazole group patients again became positive within 3-9 days after stopping 60-day therapy, whereas in the ranitidine group patients reverted to positive on day 30 of dosing while they were still on treatment and this was likely due to development of tolerance. Therefore, patients taking pantoprazole need at least a 10-day withdrawal before UBT testing, while those taking ranitidine for at least 30 days can undergo UBT without the necessity of a wash-out period.

Once-Daily Bedtime Dose of Roxatidine and Ranitidine in Acute Duodenal Ulcer: A Combined Assessment of Acid Inhibitory Activity and Healing Rate.

This study was carried out in order to compare the antisecretory effect of a single bedtime dose of roxatidine 150 mg and ranitidine 300 mg and to assess the relationship between the degree and the duration of acid suppression and the healing rates obtained in duodenal ulcer patients treated with the above regimens. Sixty-three patients with endoscopically proven ulcer underwent 24-h gastric pH-metry on day 0, day 1, and day 28 of treatment with both roxatidine and ranitidine. Ulcer healing was checked endoscopically after 4 weeks of therapy. RESULTS: Eight patients did not complete the study, leaving 55 patients eligible for final analysis, 28 in the roxatidine group and 27 in the ranitidine group. Duodenal ulcers were healed in 24--28 (85%) patients of the former and in 22--27 (81%) patients of the latter group (p minus sign NS). Gastric pH was significantly higher (p < 0.001) than basal values on days 1 and 28 with both H2-antagonists. The 24-h pH levels did not differ between day 1 and day 28 with both roxatidine and ranitidine. There was also do difference between the two active treatments. The pattern of gastric acidity significantly differed (p < 0.01) between responder (n = 46) and nonresponder (n = 9) patients to both H2-blockers, and this difference was mainly sustained by nocturnal pH. CONCLUSIONS: A bedtime close of roxatidine 150 mg and ranitidine 300 mg was able to heal more than 80% of duodenal ulcers within 4 weeks of treatment. The lack of tolerance to H2-blockers in duodenal ulcer patients contributes to this good result. The antisecretory effect of H2-antagonists is reduced in nonresponder patients with respect to responder patients and this is mainly due to an impaired control of nocturnal acidity.