Tolerance to H2 receptor antagonist correlates well with the decline in efficacy against gastroesophageal reflux in patients with gastroesophageal reflux disease.

BACKGROUND AND AIM: The attenuated antisecretory activity of H2 receptor antagonists (H2RA) during continuous administration is known as the tolerance phenomenon. The authors recently clarified that presence or absence of Helicobacter pylori infection influences the occurrence of the tolerance phenomenon. The aim of this study was to clarify whether tolerance to H2RA is correlated with attenuation of the inhibitory effect against gastroesophageal acid reflux in patients with gastroesophageal reflux disease (GERD). METHODS: Ten male patients with GERD symptoms and abnormal gastroesophageal reflux were investigated by pH monitoring on days 1 and 15 of continuous oral famotidine administration at 20 mg twice daily, and H. pylori infection was examined using the urea breath test. RESULTS: Intragastric and intraesophageal acidity were significantly decreased on the first day of famotidine administration, but then increased during the 15-day administration period in seven patients who were negative for H. pylori. In contrast, the efficacy of famotidine against gastric acid secretion and gastroesophageal acid reflux was not attenuated in three H. pylori-positive patients. The changes in GERD symptoms were correlated with the change in the degree of gastroesophageal reflux. CONCLUSION: The presence or absence of tolerance to H2RA during 15-day administration is correlated with the efficacy for inhibition of gastroesophageal acid reflux.

Comparative study of the speed of acid-suppressing effects of oral administration of cimetidine and famotidine.

BACKGROUND AND AIM: H2 histamine receptor antagonists (H2RAs) are widely used in patients with acid-related diseases, and the onset of antisecretory activity of H2RAs is reported to be faster than that of proton pump inhibitors (PPIs). The aim of this study was to compare the rapidity of onset of antisecretory activity of cimetidine and famotidine when orally administered. METHODS: Fifteen healthy male Japanese volunteers (five H. pylori-positive and 10 H. pylori-negative) participated in a randomized cross-over study. All subjects were examined three times by ambulatory 6-h pH monitoring (from 17:30 to 23:30) with no medication or oral administration of 400 mg of cimetidine or 20 mg of famotidine. Drugs were administered at 19:30 after eating a standard meal, and plasma concentrations were also examined for 4 h periods. RESULTS: The plasma concentration of cimetidine increased rapidly after oral administration, while that of famotidine increased gradually. Intragastric pH was increased and percentage time with pH < 4.0 decreased significantly 2 h after administration of either cimetidine or famotidine. There was no statistically significant difference in acid-suppressing effect between cimetidine and famotidine during the short-term post-administration period. CONCLUSION: Rapidity of antisecretory activity did not differ between oral cimetidine and famotidine administered orally.

Characteristics of gastritis in patients with Helicobacter pylori-positive reflux esophagitis.

BACKGROUND AND AIM: The influence of Helicobacter pylori on gastric acid secretion differs with the status of gastritis. The histological characteristics of gastritis in H. pylori-positive patients with reflux esophagitis have not been fully investigated. We therefore studied the pattern of endoscopic gastric mucosal atrophy and degree of histological gastritis in such patients. METHODS: Subjects comprised 41 H. pylori-positive patients with reflux esophagitis, 41 age- and sex-matched patients with duodenal ulcer, and 41 patients with early gastric cancer. The endoscopic pattern of gastric mucosal atrophy was reviewed, and the degree of histological gastritis in biopsy specimens from the antrum and corpus was assessed in accordance with the updated Sydney system. RESULTS: The grade of endoscopic and histological gastric mucosal atrophy in patients with reflux esophagitis was significantly lower than that in patients with gastric cancer, and the histological scores for antral atrophy and metaplasia in patients with reflux esophagitis tended to be lower than those in patients with duodenal ulcer. In patients with reflux esophagitis and duodenal ulcer, the scores for antral inflammation and activity tended to be higher than those for the corpus. Conversely, the inflammation and activity score in patients with early gastric cancer showed a corpus-predominant gastritis pattern. CONCLUSION: In H. pylori-positive patients with reflux esophagitis, the degree of endoscopic gastric mucosal atrophy is low and histologically there is an antral-predominant gastritis pattern. Therefore, gastric acid secretion in H. pylori-positive patients with reflux esophagitis may be augmented by H. pylori infection.

Symptom relief in patients with reflux esophagitis: comparative study of omeprazole, lansoprazole, and rabeprazole.

BACKGROUND AND AIM: Rabeprazole has a faster onset of antisecretory activity than omeprazole and lansoprazole. The aim of the present study was to clarify whether there is any difference in the speed of symptom relief in patients with reflux esophagitis following the administration of these three proton pump inhibitors (PPI). METHODS: Eighty-five patients with erosive reflux esophagitis were randomized to receive 8 weeks of 20 mg of omeprazole (n = 30), 30 mg of lansoprazole (n = 25), or 20 mg of rabeprazole (n = 30) once a morning. Daily changes in heartburn and acid reflux symptoms in the first 7 days of administration were assessed using a six-point scale (0: none, 1: mild, 2: mild-moderate, 3: moderate, 4: moderate-severe, 5: severe). RESULTS: The mean heartburn score in patients administered rabeprazole decreased more rapidly than those given the other PPI. Complete heartburn remission also occurred more rapidly in patients administered rabeprazole (compared with omeprazole: P = 0.035, compared with lansoprazole: P = 0.038 by log-rank test). No differences were seen in the rate of endoscopic healing of reflux esophagitis at 8 weeks between the three treatment regimens. CONCLUSION: Rabeprazole may be more effective than omeprazole and lansoprazole for the rapid relief of heartburn symptoms in patients with reflux esophagitis.

Nocturnal gastric acid breakthrough during the administration of rabeprazole and ranitidine in Helicobacter pylori-negative subjects: effects of different regimens.

BACKGROUND: Nocturnal gastric acid breakthrough (NAB) is defined as nocturnal intragastric pH less than 4 for more than 1 h during proton pump inhibitor (PPI) administration. A bedtime dose of an H2 receptor antagonist (H2RA) inhibites NAB, but the efficacy of the H2RA decreases with continuous administration. We carried out the present study to investigate the effect of 14-day H2RA administration on NAB. METHODS: Ten male volunteers without Helicobacter pylori infection received four different 14-day regimens of rabeprazole and ranitidine (study a, morning dose of 20 mg rabeprazole; study b, morning dose of 20 mg rabeprazole with a single bedtime dose of 150 mg ranitidine only on the last day; study c, continuous 20 mg morning dose of rabeprazole and 150 mg at bedtime; study d, morning and evening doses of 10 mg rabeprazole). Ambulatory 24-h gastric pH monitoring was conducted on the last day of each regimen. RESULTS: NAB in studies a, b, c, and d was observed in 9, 1, 4, and 4 subjects, respectively, and the longest periods of nocturnal gastric pH at less than 4.0 were 102.5, 14.0, 37.5, and 52.5 min, respectively (study b vs study c, P<0.05). CONCLUSIONS: The continuous inhibitory effect of ranitidine combined with rabeprazole on nocturnal gastric acid secretion declined during 14-day-long administration in H. pylori-negative subjects. Split dosing of rabeprazole was more effective than the single morning dose for inhibiting nocturnal gastric acid secretion.

Tolerance to famotidine and ranitidine treatment after 14 days of administration in healthy subjects without Helicobacter pylori infection.

BACKGROUND AND AIM: The attenuated antisecretory activity observed during continuous administration of ranitidine has been described as tolerance. However, it remains unclear whether a similar phenomenon occurs with other histamine H2 receptor antagonists (H2RA). We investigated whether tolerance to famotidine, a stronger H2RA than ranitidine, occurs during long-term administration. METHODS: Seven healthy male Japanese subjects without Helicobacter pylori infection participated in a randomized cross-over study in which ranitidine and famotidine were administered for 14 days with a 4-week wash-out period. We performed 24-h intragastric pH monitoring on the first and 14th days of administration of each drug, and measured serum gastrin and plasma drug concentrations on the first, seventh and 14th days. RESULTS: The acid-inhibiting activity of ranitidine and famotidine declined during continuous administration. In particular, the potent nocturnal pH-increasing effect of the H2RA, which was observed on day 1, declined on day 14. Serum gastrin concentrations on day 14 were significantly lower than those on day 7, although plasma drug concentrations remained unchanged. CONCLUSION: Tolerance to famotidine occurs during continuous administration for 14 days, as previously shown in ranitidine studies.

Influence of lansoprazole, famotidine, roxatidine and rebamipide administration on the urea breath test for the diagnosis of Helicobacter pylori infection.

BACKGROUND AND AIM: The sensitivity of the urea breath test (UBT) has been reported to be influenced by the administration of omeprazole, lansoprazole and ranitidine. However, it is unclear whether other H2 receptor antagonists (H2RA), except ranitidine, and rebamipide, a mucosal protective agent, affect UBT sensitivity. The aim of this study is to clarify the effects of lansoprazole, famotidine, roxatidine and rebamipide administration on UBT sensitivity. METHODS: Subjects comprised 30 volunteers with Helicobacter pylori infection. All subjects were examined by the 13C-UBT on four occasions: (i) without medication (control); (ii) after the administration of 30 mg lansoprazole (u.i.d) for 14 days; (iii) after the administration of 100 mg rebamipide (t.i.d) for 14 days; and (iv) after the administration of 20 mg famotidine or 75 mg roxatidine (b.i.d) for 14 days. In the H2RA study, individuals were randomized into two groups of 15 subjects and were administered either famotidine or roxatidine. RESULTS: Five of the 30 cases administered lansoprazole and one of the 15 cases given roxatidine gave a false-negative UBT result. No negative UBT results were observed in patients administered famotidine or rebamipide. CONCLUSION: Patients showing negative UBT results during the administration of proton pump inhibitors and H2RA should be re-examined after the cessation of these drugs to confirm the true negativity of H. pylori infection.