CYP2C19 genotype status and intragastric pH during dosing with lansoprazole or rabeprazole. (65/641)

BACKGROUND: CYP2C19 has an important role in the catabolism of several proton pump inhibitors. However, the relative contribution of CYP2C19-mediated metabolism varies among the different proton pump inhibitors. AIM: To determine the effect of CYP2C19 genotype status on intragastric pH during dosing with lansoprazole or rabeprazole. SUBJECTS AND METHODS: The subjects were 20 male volunteers without Helicobacter pylori infection. Their CYP2C19 genotype status was determined by a polymerase chain reaction-restriction fragment length polymorphism method. Twenty-four-hour monitoring of intragastric acidity was performed three times: once without medication, once on the last day of a 7-day course of rabeprazole, and once on the last day of a 7-day course of lansoprazole. RESULTS: Subjects were divided into three groups on the basis of their CYP2C19 genotype status: homozygous extensive metabolizers (homo-EMs, n=7), heterozygous extensive metabolizers (hetero-EMs, n=9), and poor metabolizers (PMs, n=4). The median pH during rabeprazole administration was not influenced by CYP2C19 genotype. On the other hand, the median pH in PMs during lansoprazole dosing was higher than in homo-EMs and hetero-EMs. The percentage of time with pH < 4.0 had a similar tendency to that of median pH. CONCLUSION: CYP2C19 genotype status influences gastric acid suppression by lansoprazole, but not by rabeprazole.  (+info)

Proton pump inhibitors: better acid suppression when taken before a meal than without a meal. (66/641)

BACKGROUND: Proton pump inhibitors including omeprazole and lansoprazole inhibit gastric acid secretion by selectively and non-competitively inactivating the H+, K+ ATPase molecules of the parietal cell, but possibly only those that are actively secreting acid. This might imply that stimulation of acid secretion by a meal is necessary for optimal inhibition of gastric secretion. AIM: To quantify and compare the effect on daytime gastric acidity of omeprazole 20 mg or lansoprazole 30 mg daily taken 15 min before breakfast, with that of the same drug taken without a meal. METHODS: Twenty-one healthy volunteers were randomized to receive either omeprazole or lansoprazole. They were given the drug for two separate periods of 7 days in randomized order and at least 7 days apart. During one period the study medication was taken before breakfast; during the other it was taken at the same hour, but with no meal until 12:00 hours. Lunch was standardized. On day 7, intragastric pH-metry was performed, starting at 08:00 hours. Tracings were analysed for the 8-h period from 08:00 hours until 16:00 hours with regard to percentage time for which gastric pH was below 4.0 and 3.0, and median gastric pH. Tracings were also analysed after removing the 1 h breakfast period, to exclude the buffering effect of the meal. RESULTS: When taking the drug with breakfast, the median percentage time for which gastric pH < 4.0 was 17.2 (interquartile range 4.6-45.5), compared with 42.0 (interquartile range 31.4-48.8) when taken without food (P=0.01). Fifteen subjects had better control of gastric acidity when the medication was taken with breakfast. A pH threshold of 3 and median pH showed similar differences. When the breakfast period was removed, the differences were no longer statistically significant. CONCLUSIONS: When therapy with omeprazole or lansoprazole is indicated, medication should be taken before a meal for optimal control of daytime gastric acidity.  (+info)

Efficacy of two one-week rabeprazole/levofloxacin-based triple therapies for Helicobacter pylori infection. (67/641)

BACKGROUND: One-week low-dose proton pump inhibitor-based triple therapies have usually proved to be effective treatments for Helicobacter pylori infection. AIM: To investigate the eradication efficacy, safety profile and patient compliance of two triple therapies containing a standard dose of rabeprazole and a new fluoroquinolone, levofloxacin. METHODS: One hundred patients referred to us for gastroscopy, who were H. pylori-positive, were consecutively recruited in a prospective, open-label study. The enrolled patients were randomised to receive a seven-day course of rabeprazole 20 mg o.d. plus levofloxacin 500 mg o.d. and either amoxycillin 1 g b.d. (RLA group) or tinidazole 500 mg b.d. (RLT group). Their H. pylori status was assessed by means of histology and rapid urease test at entry, and by 13C-urea breath test 8 weeks after the end of treatment. RESULTS: All 100 enrolled patients completed the study. Forty-six of 50 patients treated with RLA (both PP and ITT analysis: 92%; 95% CI: 81-98%) and 45 of 50 with RLT (both PP and ITT analysis: 90%: 95% CI: 78-97%), became H. pylori-negative. Slight or mild side-effects occurred in 4 (8%) patients of the RLA group and in 5 (10%) of the RLT group. CONCLUSIONS: This study demonstrates the efficacy of two 1-week rabeprazole-based triple therapies including levofloxacin to eradicate H. pylori. These regimens prove to be safe, well-tolerated, and achieved good eradication rates. Levofloxacin may be an effective alternative to clarithromycin in triple therapy regimens.  (+info)

The rates of common adverse events reported during treatment with proton pump inhibitors used in general practice in England: cohort studies. (68/641)

AIMS: To estimate the rates of common adverse events in patients treated with the proton pump inhibitors omeprazole, lansoprazole and pantoprazole in general practice in England. METHODS: In prescription-event monitoring cohort studies, data on dispensed prescriptions prescribed by general practitioners in England soon after each drug was launched were linked to subsequent clinical events recorded by the prescriber. 16 205 patients prescribed omeprazole between June 1989 and June 1990, 17 329 patients prescribed lansoprazole between May and November 1994, and 11 541 patients prescribed pantoprazole between December 1996 and June 1997 were studied. RESULTS: The commonest adverse events in the omeprazole, lansoprazole and pantoprazole cohorts were diarrhoea (incidence: 0. 18, 0.39 and 0.23 per 1000 days of exposure, respectively); nausea/vomiting (incidence: 0.16, 0.22 and 0.18 per 1000 days of exposure, respectively); abdominal pain (incidence: 0.17, 0.21 and 0. 17 per 1000 days of exposure, respectively); and headache (incidence rates: 0.10, 0.17 and 0.15 per 1000 days of exposure, respectively). The remaining adverse events occurred at rates of less than 0.11 per 1000 days of exposure. There were little absolute differences in the rates of most events between the three proton pump inhibitors. However, diarrhoea was more commonly associated with lansoprazole compared with omeprazole (rate difference: 0.21 per 1000 days of exposure; 95% CI 0.17, 0.25; rate ratio: 2.11; 1.78, 2.51), and there was a clear age-response relationship. CONCLUSIONS: Adverse events occurred relatively infrequently in all three cohorts. There were only small absolute differences in event rates between the three drugs, although these data suggest the hypothesis that lansoprazole is associated with more frequent occurrence of diarrhoea, particularly in the elderly.  (+info)

Potential uses of intravenous proton pump inhibitors to control gastric acid secretion. (69/641)

Proton pump inhibitors are the most effective agents for suppressing gastric acidity and are the preferred therapy for many acid-related conditions. While proton pump inhibitors have been accessible in intravenous formulations in several European countries, they have been available only as oral drugs in the United States. In the near future, the proton pump inhibitor pantoprazole is likely to become available in an intravenous formulation for American patients. Potential uses for intravenous proton pump inhibitors include treatment of Zollinger-Ellison syndrome and peptic ulcers complicated by bleeding or gastric outlet obstruction, as well as prevention of stress ulcers and acid-induced lung injury. These intravenous proton pump inhibitors are also likely to be beneficial to patients undergoing long-term maintenance with oral proton pump inhibitors who cannot take oral therapy for a period of time. Intravenous pantoprazole is especially distinguished in its lack of clinically relevant drug interactions, and it requires no dosage adjustment for patients with renal insufficiency or with mild to moderate hepatic dysfunction. Both omeprazole and pantoprazole are well tolerated in both oral and intravenous forms. Although further studies are needed to define their roles clearly, the availability of intravenous formulations of proton pump inhibitors will certainly assist with the treatment of gastric acid-related disorders.  (+info)

A novel action of the proton pump inhibitor rabeprazole and its thioether derivative against the motility of Helicobacter pylori. (70/641)

The motility of Helicobacter pylori was maximum at 37 degrees C and at pH 6. A newly developed proton pump inhibitor, rabeprazole (RPZ), and its thioether derivative (RPZ-TH) markedly inhibited the motility of H. pylori. The concentrations of the drug necessary to inhibit 50% of the motility were 0.25, 16, 16, and >64 microgram/ml for RPZ-TH, RPZ, lansoprazole, and omeprazole, respectively. No such inhibitory effects were observed with H(2) blockers or anti-H. pylori agents. The motilities of Campylobacter jejuni and C. coli-but not those of Vibrio cholerae O1 and O139, Vibrio parahaemolyticus, Salmonella enterica serovar Typhimurium, and Proteus mirabilis-were also inhibited. Prolonged incubation with RPZ or RPZ-TH inhibited bacterial growth of only H. pylori, except for a turbid colony mutant. The results indicate that RPZ and RPZ-TH have a characteristic inhibitory effect against the motility of H. pylori (spiral-shaped bacteria), which is distinguished from that against bacterial growth.  (+info)

Hypochlorhydria induced by a proton pump inhibitor leads to intragastric microbial production of acetaldehyde from ethanol. (71/641)

BACKGROUND: Acetaldehyde, produced locally in the digestive tract, has recently been shown to be carcinogenic in humans. AIM: To examine the effect of iatrogenic hypochlorhydria on intragastric acetaldehyde production from ethanol after a moderate dose of alcohol, and to relate the findings to the changes in gastric flora. METHODS: Eight male volunteers ingested ethanol 0.6 g/kg b.w. The pH, acetaldehyde level and microbial counts of the gastric juice were then determined. The experiment was repeated after 7 days of lansoprazole 30 mg b.d. RESULTS: The mean (+/- S.E.M.) pH of the gastric juice was 1.3 +/- 0.06 and 6.1 +/- 0.5 (P < 0.001) before and after lansoprazole, respectively. This was associated with a marked overgrowth of gastric aerobic and anaerobic bacteria (P < 0. 001), by a 2.5-fold (P=0.003) increase in gastric juice acetaldehyde level after ethanol ingestion, and with a positive correlation (r=0. 90, P < 0.001) between gastric juice acetaldehyde concentration and the count of aerobic bacteria. CONCLUSIONS: Treatment with proton pump inhibitors leads to hypochlorhydria, which associates with intragastric overgrowth of aerobic bacteria and microbially-mediated acetaldehyde production from ethanol. Since acetaldehyde is a local carcinogen in the concentrations found in this study, long-term use of gastric acid secretory inhibitors is a potential risk-factor for gastric and cardiac cancers.  (+info)

High-dose ecabet sodium improves the eradication rate of helicobacter pylori in dual therapy with lansoprazole and amoxicillin. (72/641)

AIM: The additive effect of ecabet sodium in combination with dual therapy on Helicobacter pylori eradication was evaluated. METHODS: H. pylori-positive chronic gastritis patients were randomly assigned to one of the following three groups and medicated for 2 weeks. Group LA: dual therapy (lansoprazole 30 mg o.d. plus amoxicillin 750 mg b.d.). Group LA1E: dual therapy plus ecabet sodium (1 g b.d.). Group LA2E: dual therapy plus ecabet sodium (2 g b.d.). Patients were evaluated 4 weeks after the cessation of treatment by culture and 13C-urea breath test. RESULTS: Seventy-one patients (mean age, 56.6 years; range, 26-79 years; 40 males, 31 females) were enrolled in this prospective, single-blind study, and 68 completed the protocol. The eradication rates per protocol patient were 43% in group LA, 62% in group LA1E, and 79% in group LA2E, and those on the intention-to-treat basis were 42% in group LA, 57% in group LA1E and 79% in group LA2E. The eradication rate in group LA2E was significantly higher than group LA (P=0.032 in per protocol, P=0.022 in intention-to-treat). Adverse effects were observed in 10 patients in this study. There were no severe adverse effects caused by ecabet sodium. CONCLUSION: High-dose ecabet sodium increases eradication rates of H. pylori in dual therapy with lansoprazole and amoxicillin.  (+info)