Yoshinori Komazawa

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.

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).

Ulinastatin shows preventive effect on post-endoscopic retrograde cholangiopancreatography pancreatitis in a multicenter prospective randomized study

Background and Aim:  Endoscopic retrograde cholangiopancreatography (ERCP) is a useful diagnostic and therapeutic procedure; however, ERCP occasionally causes post‐ERCP pancreatitis. The administration of gabexate mesilate has been reported to be effective for the prevention for post‐ERCP pancreatitis when given during and after the procedure. The aim of the present study was to investigate the preventive effect of the novel protease inhibitor ulinastatin on post‐ERCP pancreatitis.

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.

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.

Helicobacter pylori infection prevents the occurrence of the tolerance phenomenon of histamine H2 receptor antagonists

Background : The attenuated anti‐secretory activity of H2 receptor antagonists (H2RA) during continuous administration is referred to as the tolerance phenomenon. However, it is not clarified whether Helicobacter pylori infection affects the occurrence of tolerance to H2RA. It is also not clarified whether the tolerance phenomenon occurs to a new H2RA, lafutidine.

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).

Pulse-wave velocity and cardiovascular risk factors in subjects with Helicobacter pylori infection

Background: Helicobacter pylori infection has been reported to correlate with the onset of cardiovascular diseases. However, the relationship between H. pylori infection and the development of arteriosclerosis has not been fully investigated. We performed a cross‐sectional study to clarify the possible role of H. pylori infection in the development of arteriosclerosis.

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.

Diarrhea Caused by Proton Pump Inhibitor Administration: Comparisons Among Lansoprazole, Rabeprazole, and Omeprazole

BACKGROUND The number of patients who require treatment with proton pump inhibitors (PPIs) is increasing in Japan. One of their adverse effects is diarrhea. OBJECTIVES We investigated the incidence of diarrhea caused by 3 different PPIs: lansoprazole, rabeprazole, and omeprazole. METHODS Patients using PPIs for >1 month were enrolled. Enrolled patients recorded daily stool frequency, stool consistency using the Bristol Stool Scale Form, and impaired quality of life caused by diarrhea for 1 month. Their attending physicians described the types and dosages, and duration of PPI administration, as well as other necessary information. RESULTS A total of 255 patients participated. Mean age of the patients was 70.7 years old. During the 1-month observation period, 3.5% of the patients complained of diarrhea. There was no significant difference for the incidence of diarrhea among the 3 types of PPIs. Furthermore, no correlations between diarrhea and length and dosage of PPI administration were found. CONCLUSIONS The incidence of diarrhea in patients receiving long-term therapy did not differ among 3 different PPIs. ClinicalTrials.gov identifier: UMIN ID 000005300.