Time to maximum effect of lansoprazole on gastric pH in normal male volunteers

Effect of Acid Suppressants on Non–Helicobacter pylori Helicobacters Within Parietal Cells

We investigated the effect of increased pH induced by acid suppressants on the viability of non–Helicobacter pylori helicobacters (NHPHs) within parietal cell intracellular canaliculi and fundic glandular lumina by immunohistochemistry, electron microscopy, quantitative PCR, urea breath tests, and using a bilayer culture system. Three months before the experiment, mice were infected with the NHPH H. suis and then treated with famotidine (2 mg/kg body weight [BW], once daily), lansoprazole (30 mg/kg BW, once daily), or vonoprazan (20 mg/kg BW, once daily) for 3 days. Immunohistochemical studies using the TUNEL method, quantitative PCR analysis, and urea breath tests were performed. PCR analysis showed a decrease in the NHPH quantity after vonoprazan treatment. Urea breath tests revealed a significant decrease in the NHPH urease activity after vonoprazan, lansoprazole, and famotidine treatments for 3 days; however, 4 days after the treatment, urease activity reversed to the pretreatment level for each treatment group. Electron microscopy revealed an increase in the damaged NHPH after vonoprazan treatment. The TUNEL method revealed apoptotic NHPH within parietal cells after vonoprazan treatment. The bilayer culture results demonstrated that NHPH moved more quickly at a pH of 4.0 than at a pH of 3.0, 5.0, and 6.5, and electron microscopy revealed a change from the spiral form to the coccoid form under near-neutral pH conditions. We thus proposed that acid suppressants, especially vonoprazan, induce NHPH damage by altering pH.

The Impact of Gastric Juice pH on the Intraluminal Therapy for Helicobacter pylori Infection

Background: Helicobacter pylori (H. pylori) can be topically eradicated in stomach lumen on endoscopic examination. The procedures of intraluminal therapy for H. pylori infection (ILTHPI) include the control of intragastric pH, mucolytic irrigation of the gastric mucosal surface, and a single-dose medicament containing antimicrobial agents. Aims: To detect gastric juice pH and evaluate its impact on the success rate of ILTHPI. Methods: We enrolled 324 patients with upper abdominal discomfort for endoscopic examinations. Among them, 13C-urea breath test was positive in 218 patients, where 100 underwent ILTHPI, and negative in 106. All patients had their gastric juice pH detected and set into three ranges, including normal acidity (pH < 4.0), low-level hypoacidity (pH 4.0–5.5), and high-level hypoacidity (pH ≥ 6.0). The impact of gastric juice pH on the success rate of ILTHPI was evaluated. Results: Distribution of pH level showed no significant difference between two groups of H. pylori-infected patients (p = 0.942). The eradication rate of ILTHPI is significantly lower in patients with gastric juice pH below 4 (p < 0.001). Conclusions: Detection of gastric juice pH in ILTHPI is extremely important. Rapid control of stomach pH at or above 4 for patients prior to ILTHPI is strongly recommended. (NCT03124420).

Intraluminal therapy for Helicobacter pylori infection

BACKGROUND AND AIM

Several strategies have been proposed to increase the eradication rate of Helicobacter pylori. However, the widespread increasing resistance rates to current multiple-dose oral antibiotic therapies call for alternative therapeutic approaches. We aim to develop a novel intraluminal therapy for H. pylori infection (ILTHPI).

METHODS

From April 2017 to December 2017, 100 H. pylori-infected treatment-naïve patients with upper abdominal pain or discomfort underwent endoscopic examinations and concomitant ILTHPI, which comprised the control of intragastric pH, the irrigation of gastric mucosal surface with a mucolytic agent, and the application of single-dose medicaments containing antibiotic powders. The safety profiles while conducting ILTHPI and adverse events after ILTHPI were evaluated. The success of eradication was assessed based on the result of the ¹³ C-urea breath test 6 weeks after ILTHPI. In addition, a patient with successful ILTHPI was reconfirmed by a negative H. pylori stool antigen test four to 6 months after ILTHPI to exclude short-term recurrence.

RESULTS

All the 100 enrolled patients completed the ILTHPI with good safety profiles and mild adverse events (6%). Five patients dropped out, and 51 of 95 patients (53.7%) achieved successful eradication immediately after endoscopic examinations. All 51 patients revealed negative stool H. pylori antigen tests four to 6 months after successful ILTHPI. No short-term recurrence was observed.

CONCLUSIONS

We have developed a novel therapeutic approach. With the ILTHPI, H. pylori can be eradicated immediately by administrating a single-dose regimen while conducting an endoscopic examination.

CLINICAL TRIALS NUMBER

NCT03124420.

Efficacy of on-demand therapy using 20-mg vonoprazan for non-erosive reflux disease

BACKGROUND

To evaluate the efficacy of on-demand therapy using 20-mg vonoprazan for non-erosive reflux disease.

METHODS

On-demand therapy by taking one 20-mg tablet of vonoprazan only when reflux symptoms occurred was performed for 8 weeks by 30 patients (11 men, mean age: 67.8) with non-erosive reflux disease who responded well to maintenance therapy using proton pump inhibitor and answered "very satisfied" or "satisfied" to an overall satisfaction survey (5-grade scale). The degree of overall satisfaction with the treatment, score of symptoms, and fasting gastrin levels before breakfast was examined before and after on-demand therapy. The number of vonoprazan tablets taken and the frequency (regular, temporary, rare) of its administration were also investigated.

RESULTS

All patients completed 8-week on-demand therapy with 20-mg vonoprazan. Comparisons of patient satisfaction levels before and after therapy revealed no significant differences in the number of patients who were very satisfied and satisfied with the therapy. Furthermore, there were no significant differences in score of symptoms or gastrin levels before and after therapy. During 8-week on-demand therapy, patients took 11 tablets (median) (7.0-18.0 tablets: 25-75 percentiles), and 30.0% of patients (n = 9) took vonoprazan on a regular basis (at least 2 tablets a week).

CONCLUSION

On-demand therapy with 20-mg vonoprazan exerted equivalent effects to continuous PPI maintenance therapy for patients with non-erosive reflux disease.

Efficacy of On-Demand Therapy Using 20-mg Vonoprazan for Mild Reflux Esophagitis

BACKGROUND

The study aimed to evaluate the efficacy of on-demand therapy using 20-mg vonoprazan for mild reflux esophagitis (RE).

METHODS

On-demand therapy by taking one 20-mg tablet of vonoprazan only when reflux symptoms occurred was performed for 24 weeks using 30 patients with mild RE who were receiving maintenance therapy with proton pomp inhibitors (PPIs). The presence or absence of RE, degree of overall satisfaction with the treatment, score of symptoms, and fasting gastrin level before breakfast were examined before and after on-demand therapy. The number of tablets taken during the 24-week period was also noted.

RESULTS

One of the 30 patients dropped out of on-demand therapy 1 week after its initiation. Remission was maintained in 25 (86.2%) of the 29 patients (all 10 [100%] Los Angeles classification grade A patients and 15 (78.9%) of the 19 grade B patients). However, 4 grade B patients exhibited grade B relapse. There were no differences in the degree of overall satisfaction, score of symptoms or the gastrin level between PPI and on-demand therapies. The number of vonoprazan tablets taken during the observation period was 33 tablets (median)/24 weeks.

CONCLUSION

On-demand therapy using 20-mg vonoprazan tablets is an effective alternative maintenance therapy for mild RE.

Pharmacokinetics of neratinib during coadministration with lansoprazole in healthy subjects

AIMS

To evaluate the effect of lansoprazole, a proton-pump inhibitor, on the absorption, pharmacokinetics, and safety of neratinib, a pan-HER tyrosine kinase inhibitor, in healthy subjects.

METHODS

This was an open-label, two-period, fixed-sequence study. Fifteen healthy adult subjects received a single oral dose of neratinib 240 mg (Period 1), followed by a washout period, then oral lansoprazole 30 mg once daily for 7 days and a single dose of neratinib 240 mg on Day 5 (Period 2). Pharmacokinetic sampling was performed for 72 h following each neratinib dose. Plasma neratinib concentration-time data were analysed using noncompartmental methods. Geometric mean ratios for AUC_0-t , AUC_0-inf , and peak plasma concentrations (C_max ) for neratinib plus lansoprazole vs. neratinib were used to assess the magnitude of the drug-drug interaction if the 90% confidence intervals were outside 80.00-125.00%.

RESULTS

Neratinib geometric least-squares mean (LSM) C_max was reduced from 84.5 ng ml^-1 with neratinib alone to 24.5 ng ml^-1 with neratinib plus lansoprazole. The extent of exposure to neratinib was also decreased: geometric LSM AUC_0-t was 1478 ng ml^-1  h with neratinib vs. 426 ng ml^-1  h with neratinib plus lansoprazole, and geometric LSM AUC_0-inf was 1557 ng ml^-1  h vs. 542 ng ml^-1  h, respectively. Mean t_½ was similar with both treatments (approximately 14 h). Geometric mean ratios 90% confidence intervals for AUC_0-t , AUC_0-inf and C_max fell outside the prespecified equivalence range (80.0-125.0%). Treatment-emergent adverse events, all mild, were reported by five (33%) subjects.

CONCLUSIONS

Coadministration of lansoprazole with neratinib reduced the rate and extent of neratinib exposure in healthy subjects.

Evaluation of the effect of multiple doses of lansoprazole on the pharmacokinetics and safety of ponatinib in healthy subjects

BACKGROUND

In vitro studies have demonstrated that the aqueous solubility of the tyrosine kinase inhibitor ponatinib decreases as pH increases.

OBJECTIVES

The primary aim of this study was to assess the effects of the gastric proton pump inhibitor lansoprazole on the pharmacokinetics of ponatinib. The single-dose safety profile of ponatinib with and without coadministration of lansoprazole was also characterized.

METHODS

This was a phase I, open-label, non-randomized, two-period crossover study in 20 healthy subjects aged 18-55 years. Subjects received a single oral dose of ponatinib 45 mg alone on day 1, an oral dose of lansoprazole 60 mg on day 14, and ponatinib 45 mg plus lansoprazole 60 mg on day 15.

RESULTS

Lansoprazole coadministration resulted in a 1-h increase in the time to maximum plasma concentration (t max) of ponatinib (6 vs. 5 h post-dose; P < 0.001). A corresponding 25 % decrease in the geometric mean maximum plasma concentration (C max) of ponatinib was observed for ponatinib + lansoprazole versus ponatinib alone (40.67 vs. 53.96 ng/mL). Importantly, lansoprazole did not decrease the overall ponatinib systemic exposure as assessed by the ponatinib area under the plasma concentration-time curve from time zero to infinity (AUC∞ 1,153 ng·h/mL for lansoprazole + ponatinib vs. 1,222 ng·h/mL for ponatinib alone). The safety profile was considered acceptable when ponatinib was administered alone or with lansoprazole.

CONCLUSIONS

Although coadministration of lansoprazole led to a modest, albeit statistically significant, reduction in ponatinib C max, overall systemic exposure to ponatinib did not change. The findings suggest that no dose adjustment is necessary when ponatinib is administered with drugs that increase gastric pH.

A clinical study to examine the potential effect of lansoprazole on the pharmacokinetics of bosutinib when administered concomitantly to healthy subjects

BACKGROUND

Bosutinib is an orally bioavailable, dual Src and Abl tyrosine kinase inhibitor approved in the USA for the treatment of Philadelphia chromosome-positive chronic myeloid leukemia following development of resistance or intolerance to prior therapy. In vitro studies demonstrated that bosutinib displays pH-dependent aqueous solubility, suggesting that concomitant administration of agents that alter gastric pH could affect bosutinib absorption.

OBJECTIVES

The objectives of this study were to evaluate the effect of lansoprazole, a gastric proton pump inhibitor, on the pharmacokinetics and safety of bosutinib.

METHODS

This open-label, non-randomized, phase I study involved inpatients and outpatients at a single site. The study participants were healthy men or women of non-childbearing potential aged 18-50 years. Each subject received bosutinib 400 mg on Day 1, lansoprazole 60 mg on Day 14, and bosutinib 400 mg co-administered with lansoprazole 60 mg on Day 15 under fasting conditions. The main outcome measure was the effect of multiple doses of lansoprazole on the pharmacokinetic profile of a single oral dose of bosutinib.

RESULTS

A total of 24 healthy male subjects were enrolled. Co-administration with lansoprazole decreased the mean maximum plasma concentration (C(max)) of bosutinib from 70.2 to 42.9 ng/mL, and the total area under the plasma concentration-time curve (AUC) from 1,940 to 1,470 ng·h/mL. Log-transformed bosutinib pharmacokinetic parameters indicated significant between-treatment differences; the least squares geometric mean ratio for C(max) was 54 % (95 % CI 42-70) and for AUC was 74 % (95 % CI 60-90). Mean apparent total body clearance from plasma after oral administration increased from 237 to 330 L/h, and the median time to reach Cmax increased from 5 to 6 h, although this change may be related to decreased bosutinib absorption when combined with lansoprazole. When co-administered with lansoprazole, bosutinib maintained an acceptable safety profile, which was primarily characterized by diarrhea (33 %), headache (21 %), and nausea (13 %). One subject experienced serious adverse events of diverticulitis, gastritis, and duodenitis after co-administration; however, no participant withdrew because of toxicity.

CONCLUSIONS

This study demonstrated that bosutinib absorption may be reduced when co-administered with lansoprazole or other proton pump inhibitors. Caution should be used with such drug combinations, as subtherapeutic exposure of bosutinib may limit its clinical antitumor activity; short-acting antacids are recommended instead.

Intragastric acidity during the first day following administration of low-dose proton pump inhibitors: a randomized crossover study

OBJECTIVE

Low-dose proton pump inhibitors (PPIs) are often administrated as maintenance therapy for gastroesophageal reflux disease (GERD) and on-demand PPI therapy is a viable option for long-term management of GERD. The aim of this study is to investigate intragastric acidity during the first day following the administration of low-dose PPIs.

SUBJECTS AND METHODS

The study employed a crossover design. The subjects were 10 healthy volunteers who were administrated lansoprazole 15 mg (orally disintegrating) or rabeprazole 10mg. All subjects underwent pH monitoring with a wireless system during the first day after PPI administration.

RESULTS

There was no significant difference in the average intragastric pH during the first day of administration of lansoprazole and rabeprazole (3.3±1.1 vs. 3.2±0.7, paired t test), although the pH was significantly higher with both drugs as compared with the baseline (1.8±0.4, P<0.01). The pH 4 holding time ratio during the first day showed no significant difference between lansoprazole and rabeprazole (35.2±22.4% vs. 34.3±15.0%), and was also significantly higher than at baseline (0.35±1.73%, P<0.01). The two PPIs differed with respect to the peak of the pH 4 holding time ratio.

CONCLUSIONS

Lansoprazole 15 mg and rabeprazole 10 mg showed sufficient inhibition of intragastric acidity during the first day after PPI administration and the effects did not differ between drugs, although there was a difference in their time at which the peak effects were reached.

Characterization of muco- and bioadhesive properties of chitosan, PVP, and chitosan/PVP blends and release of amoxicillin from alginate beads coated with chitosan/PVP

PURPOSE

To investigate the muco/bioadhesive properties of chitosan, polyvinylpyrrolidone (PVP), and chitosan/PVP blends and the release of amoxicillin (AMX) contained in AMX-alginate beads coated with these materials.

METHOD

Chitosan, PVP, and chitosan/PVP blends at various volume ratios were coated onto calcium alginate beads containing AMX. The muco/bioadhesive properties of all materials and the AMX-alginate beads coated with these materials were characterized.

RESULTS

Measurements of their viscosity, texture, and adhesion to HT29 cells demonstrated that chitosan/PVP at a volume ratio of 5/5 had the best muco/bioadhesive properties when compared with chitosan, PVP, and blends of other ratios. Wash-off tests indicated that the mucoadhesive property of the coated AMX-alginate beads was significantly higher than that of the uncoated beads. Diffuse reflectance infrared Fourier transform spectroscopy showed that there were interactions between chitosan-PVP, chitosan-mucin, PVP-mucin, and chitosan/PVP blend-mucin. Scanning electron microscopy revealed that the surfaces of the coated beads were smoother than those of the uncoated beads. All coated AMX-alginate beads were able to provide a controlled release of AMX with Super Case II transport properties, at a pH of 4. This was probably a result of the rapid and extensive swelling of the alginate beads. The more rapid release of AMX at pH 1 was probably because of the rapid dissolution of the drug at this pH.

CONCLUSIONS

From the controlled drug release and muco/bioadhesive properties of these coated AMX-alginate beads, we suggest that the alginate-coated beads might be a promising drug delivery system to assist with the eradication of Helicobacter pylori infections.

Clinical trial: inhibitory effect of revaprazan on gastric acid secretion in healthy male subjects

BACKGROUND AND AIM

Revaprazan is a novel acid pump antagonist. The aim of this study was to investigate the inhibitory effect of revaprazan on gastric acid secretion in healthy male subjects.

METHODS

In a double-blind, three-way cross-over study, 30 healthy male volunteers were randomized to 100, 150 or 200 mg of oral revaprazan daily for 7 days. Serum gastrin concentration was measured, and 24-h intragastric pH was recorded at baseline and on days 1 and 7 of each administration period. Serial blood samples were processed for pharmacokinetics.

RESULTS

Median intragastric pH over 24 h and mean percentage time that pH was > 4 increased in a dose-dependent manner and were significantly higher on days 1 and 7 compared with baseline in all groups (P < 0.05). The antisecretory effect of revaprazan was rapid and nearly maximal on day 1 in all groups. Serum gastrin levels were rapidly normalized by 100 and 150 mg/day of revaprazan on days 1 and 7, but were significantly higher in the 200 mg/day revaprazan group. The pharmacokinetic effect was rapidly absorbed and eliminated on days 1 and 7 in all groups.

CONCLUSIONS

Revaprazan rapidly and effectively inhibits gastric acid secretion in healthy male subjects. Therefore, revaprazan can be used as an effective drug for acid-related disease.

Recurrent community-acquired pneumonia in patients starting acid-suppressing drugs

BACKGROUND

Several studies suggest that proton pump inhibitors (PPIs) and histamine 2-receptor antagonists (H2s) increase risk of community-acquired pneumonia. To test this hypothesis, we examined a prospective population-based cohort predisposed to pneumonia: elderly patients (> or =65 years) who had survived hospitalization for pneumonia.

METHODS

This study featured a nested case-control design where cases were patients hospitalized for recurrent pneumonia (> or =30 days after initial episode) and controls were age, sex, and incidence-density sampling matched but never had recurrent pneumonia. PPI/H2 exposure was classified as never, past, or current use before recurrent pneumonia. The association between PPI/H2s and pneumonia was assessed using multivariable conditional logistic regression.

RESULTS

During 5.4 years of follow-up, 248 recurrent pneumonia cases were matched with 2476 controls. Overall, 71 of 608 (12%) current PPI/H2 users had recurrent pneumonia, compared with 130 of 1487 (8%) nonusers (adjusted odds ratio [aOR] 1.5; 95% confidence interval [CI], 1.1-2.1). Stratifying the 608 current users according to timing of PPI/H2 initiation revealed incident current-users (initiated PPI/H2 after initial pneumonia hospitalization, n=303) bore the entire increased risk of recurrent community-acquired pneumonia (15% vs 8% among nonusers, aOR 2.1; 95% CI, 1.4-3.0). The 305 prevalent current-users (PPI/H2 exposure before and after initial community-acquired pneumonia hospitalization) were equally likely to develop recurrent pneumonia as nonusers (aOR 0.99; 95% CI, 0.63-1.57).

CONCLUSION

Acid-suppressing drug use substantially increased the likelihood of recurrent pneumonia in high-risk elderly patients. The association was confined to patients initiating PPI/H2s after hospital discharge. Our findings should be considered when deciding to prescribe these drugs in patients with a recent history of pneumonia.

Ninety-six-hour wireless oesophageal pH monitoring following proton pump inhibitor administration in NERD patients

BACKGROUND

Comparative studies of proton pump inhibitors (PPIs) have revealed that acid reflux is influenced by PPI treatment, formulations and dosing regimens. Wireless pH capsules have circumvented some of the limitations of conventional catheter-based pH testing with the additional advantage of 96-h recording periods.

AIM

To clarify the effectiveness of intra-oesophageal acid suppression by omeprazole, pantoprazole and lansoprazole in non-erosive reflux disease patients through a 4-day monitoring of oesophageal pH and related symptoms.

METHODS

Twenty-four patients with typical symptoms of gastro-oesophageal reflux disease were enrolled and administered upper endoscopy and placement of a wireless pH capsule. Patients randomly received omeprazole, pantoprazole or lansoprazole for 3 days after the first 24 h. Symptom-reflux associations were expressed using the symptom index (SI).

RESULTS

All patients completed the study. Significant decrease in acid exposure occurred on day 2 and in each successive day in all groups. Pantoprazole and omeprazole are more effective than lansoprazole at inducing a normalization of intra-oesophageal acid exposure at days 2 and 3. Significant reduction in SI at day 2 was observed.

CONCLUSIONS

Four-day ambulatory oesophageal pH monitoring is feasible and safe. Omeprazole, pantoprazole and lansoprazole have an equivalent potency for normalizing intra-oesophageal acid exposure after 3 days of treatment in non-erosive reflux disease patients.

Four-day continuous gastric pH monitoring following anti-acid secretory drug administration: cross-over test to assess the early effects

BACKGROUND

There have been few reports that compare the effect of histamine H2-receptor antagonists (H2RAs) and proton pump inhibitors (PPIs) using continuous gastric pH monitoring for a long duration.

AIM

To assess the early effects of both drugs on gastric pH using a wireless pH monitoring system.

METHODS

The test was conducted by a cross-over test: 10 healthy male volunteers were administered famotidine 20 mg twice a day and lansoprazole 30 mg once a day. Monitoring of gastric pH over four consecutive days was performed using a unique method we have developed that is an elaboration of the Bravo system.

RESULTS

The time to reach a pH level of 3 or more with famotidine was significantly shorter than that for lansoprazole. The pH3 holding time ratio of famotidine during the first 4 h of administration was significantly higher than that of lansoprazole. The pH3 holding time ratio on each day from day 1 to day 3 was significantly higher following lansoprazole administration compared with famotidine administration.

CONCLUSIONS

Famotidine was shown to act quickly in elevating gastric pH; however, lansoprazole was superior to famotidine in terms of its ability to elevate gastric pH for a long duration.

Comparison of the effects of single and repeated oral doses of lansoprazole and rabeprazole on ambulatory 24-hour intragastric pH in healthy volunteers

BACKGROUND

As the comparative pharmacokinetics and pharmacodynamics of lansoprazole and rabeprazole have not previously been studied, we set out in this study to compare the pharmacokinetics and pharmacodynamics of single and repeated daily doses of lansoprazole 15 mg and 30 mg with those of rabeprazole 10 mg and 20 mg.

METHODS

This was an open-label, randomised, crossover, two-centre study in 72 healthy volunteers. Each subject received each of the four treatments for 5 days, with 2-week washout periods. Continuous 24-hour intragastric pH and pharmacokinetics were studied on days 1 and 5.

RESULTS

Mean 24-hour pH and percentage time for pH > 4 were not significantly different between lansoprazole 30 mg and rabeprazole 20 mg. Mean 24-hour pH and percentage time for pH > 4 were significantly greater after lansoprazole 30 mg and rabeprazole 20 mg than after lansoprazole 15 mg and rabeprazole 10 mg, respectively. Lansoprazole resulted in greater acid suppression during hours 0-5 on days 1 and 5, whereas rabeprazole had greater suppression during hours 11-24 on day 5. Time to maximum plasma concentration was significantly shorter for lansoprazole on both days.

CONCLUSION

Lansoprazole had a consistently faster onset of action, whereas rabeprazole had a greater effect during the evening hours after 5 days of administration.

Changes in gastric environment with test meals affect the performance of 14C-urea breath test

BACKGROUND

(14)C-urea breath test (UBT) is considered to be an accurate diagnostic test for the detection of active Helicobacter pylori infection. Various test meals are used in (14)C-UBT to slow down gastric emptying, and to enhance the gastric distribution, in order to increase the time and area of contact between microorganisms and the tracer substrate. The aim of the present paper was to evaluate the effect of gastric environment on the performance of (14)C-UBT using an alkaline and an acidic liquid test meal having gastric emptying retardant effect.

METHODS

The comparison of (14)C-UBT was done with liquid test meals (200 mL water) comprising (i) plain drinking water (PDW); (ii) 1.3 g or 3.0 g citric acid (CA); and (iii) 3.0 g trisodium citrate (TSC). Eighteen patients (37 +/- 12 years, range 18-57 years) with complaints of dyspepsia participated in the study. The status of H. pylori was confirmed by histology and rapid urease test. A total of 93 kBq of (14)C-urea (0.5 mL) in a gelatin capsule was orally administered along with liquid test meals to the overnight fasting subjects. Breath samples were collected and radioactivity measured. Results were expressed as (14)CO(2)/mmol exhaled CO(2) as percentage of administered radioactive urea.

RESULTS

Higher acidic gastric environment (pH approx. 2.0) with CA was found to increase the exhaled (14)CO(2) level in a dose-dependent manner as compared to PDW and TSC meal (P < 0.05) at all time points. With TSC test meal, the expired (14)CO(2) level decreased in the lower acidic gastric environment (pH approx. 5.3). The peaks of exhaled (14)CO(2) with TSC test meal were observed at the same time points as that with PDW and CA test meals. The (14)C-UBT with TSC was found to be positive in 77% of patients (10/13).

CONCLUSION

Better interaction between the microbial urease and (14)C-urea, caused by a test meal that retards gastric emptying and that changes gastric pH, plays an important role in hydrolysis of the administered (14)C-urea by H. pylori urease.

Frequency analyses of gastric pH in control and gastro-oesophageal reflux disease subjects treated with a proton-pump inhibitor

BACKGROUND

We are unaware of any solid theoretical or pathophysiological basis for selecting pH 4 or any other pH value to assess gastric acidity.

AIM

To examine the frequency of different gastric pH values in control and GERD subjects.

METHODS

Gastric pH was measured for 24 h in 26 control subjects, 26 gastro-oesophageal reflux disease subjects at baseline and the same 26 gastro-oesophageal reflux disease subjects during treatment with a proton-pump inhibitor. Histograms were constructed using the 21 600 values generated from each recording and bins of 0.25 pH units.

RESULTS

The distribution of gastric pH values in gastro-oesophageal reflux disease subjects was significantly different from that in controls and in some instances the distributions detected significant differences that were not detected by integrated acidity. Proton-pump inhibitor treatment significantly altered the distribution of gastric pH values and the nature of this alteration during the postprandial period was different from that during the nocturnal period. Using time pH< or =4 can significantly underestimate the magnitude of inhibition of gastric acidity caused by a proton-pump inhibitor.

CONCLUSIONS

The distribution of gastric pH values provides a rationale for selecting a particular pH value to assess gastric acidity. In some instances, the distribution of gastric pH values detects significant differences between gastro-oesophageal reflux disease and normal subjects that are not detected by integrated acidity.

Therapeutic choices in reflux disease: defining the criteria for selecting a proton pump inhibitor

Gastroesophageal reflux disease (GERD) is among the most common disorders of the gastrointestinal tract, with symptoms affecting a substantial proportion of the US population on a daily basis. Heartburn and related symptoms arise from a number of pathophysiologic mechanisms, including dilated intercellular spaces, increased duration of acid reflux, greater proximal extent of reflux, and esophageal sensitivity. Chronic reflux may result in serious complications, such as esophageal erosions or ulceration, stricture, and Barrett esophagus. The goals of GERD therapy are to relieve patients' symptoms and prevent complications. Proton pump inhibitors (PPIs) represent the most effective treatment option for GERD, relieving symptoms, healing erosions, and maintaining a healed mucosa. Differences in the pharmacokinetics and pharmacodynamics among the PPIs may result in differences in intragastric pH holding time as well as the onset of symptom relief. Lansoprazole and esomeprazole produce similar degrees and onset of symptom relief, with both providing greater symptom relief as compared with omeprazole. Although manufactured as capsules containing enteric-coated granules, lansoprazole, omeprazole, and esomeprazole maintain their high level of pharmacologic efficacy when the capsule contents are emptied into soft foods or various liquids. Lansoprazole and pantoprazole also are manufactured as intravenous formulations, and lansoprazole is available as strawberry-flavored granules for oral suspension and as an orally disintegrating tablet. These alternative routes of administration are particularly beneficial in the management of acid-related disorders in infants, children, the elderly, and patients of all ages who have difficulty swallowing or are unable to swallow intact capsules or tablets and those in the critical care setting.

Evaluation of the pharmacokinetics and pharmacodynamics of intravenous lansoprazole

AIM

To compare the pharmacokinetics and pharmacodynamics of lansoprazole 30 mg administered intravenously in 0.9% NaCl or in polyethylene glycol, or orally.

METHODS

Twenty-nine subjects received lansoprazole orally on days 1-7 and intravenous lansoprazole in NaCl on days 8-14. Blood samples were collected on days 1, 7, 8 and 14. Fasting basal acid output and pentagastrin-stimulated maximal acid output were determined on days -1, 8, 9 and 15. Thirty-six different subjects received one of four regimen sequences: intravenous lansoprazole in NaCl, intravenous in polyethylene glycol, per orally, or intravenous placebo, each for 5 days. Twenty-four hour intragastric pH was recorded on days 1 and 5.

RESULTS

Intravenous and per oral lansoprazole for 7 days produced equivalent basal acid output and maximal acid output suppression. Pharmacokinetics and mean pH values with intravenous lansoprazole in NaCl or polyethylene glycol were equivalent. Both produced mean pH and percentages of time pH above 3, 4, 5 and 6 that were significantly greater than did per orally.

CONCLUSIONS

Intravenous lansoprazole inhibits acid secretion as effectively in NaCl as in polyethylene glycol, and its onset of action is faster than per oral lansoprazole.

Pharmacokinetic and pharmacodynamic evaluation of a novel proton pump inhibitor, YH1885, in healthy volunteers

To evaluate the pharmacokinetic and pharmacodynamic characteristics of YH1885, a novel proton pump inhibitor, a single-blind, randomized, placebo-controlled, dose-rising, parallel-group study was conducted in 46 healthy volunteers. The volunteers were randomly allocated to single dose groups of 60 mg, 100 mg, 150 mg, 200 mg, and 300 mg (6 subjects per dose, including 2 placebos) or to multiple-dose groups of 150 mg and 300 mg (once-daily dosing for 7 days; 8 subjects per dose, including 2 placebos). The multiple-dose study was conducted separately after the single-dose study. YH1885 was administered orally after overnight fasting. Serial blood samples, urine samples, and pharmacodynamic measurements were taken. Drug concentrations in plasma and urine were determined by liquid chromatography/mass spectrometry (LC/MS). Pharmacodynamic changes were evaluated by ambulatory intragastric pH monitoring and by serial measurements of serum gastrin concentrations. Assessments of safety and tolerability also were made. Plasma concentrations of YH1885 reached peak levels 1.3 to 2.5 hours after single-dose administration and then declined monoexponentially with a terminal half-life (t(1/2)) of 2.2 to 2.4 hours in dosage groups up to 200 mg in the single-dose study. YH1885 showed linear pharmacokinetic characteristics, and little accumulation occurred after multiple administrations. The parent drug was not detected in urine. Dose-related pharmacological effects were obvious for dose groups of 150 mg and higher in the single-dose study. The mean intragastric pH and the percentage of time at pH>4 were significantly increased. The onset of drug effect was rapid, and maximal effects were observed on the first day of administration during multiple dosing. Serum gastrin levels also showed rapid increases during dosing but with a weak dose-effect relationship. Neither serious nor dose-limiting adverse effects were observed. YH1885 was found to be safe and well tolerated and effectively inhibited acid secretion with dose-dependent increases in intragastric pH. The acid-suppressing efficacy of YH1885 needs to be further evaluated in patients with gastric acid-related diseases.

Comparative pharmacokinetics and safety of lansoprazole oral capsules and orally disintegrating tablets in healthy subjects

BACKGROUND

Many individuals with acid-related gastrointestinal disorders have difficulty in swallowing oral agents.

AIM

To compare the bio-availability of a single dose of lansoprazole orally disintegrating tablet with that of an intact capsule.

METHODS

One hundred and twenty healthy subjects participated in two prospective, Phase I, open-label, two-period cross-over studies to receive lansoprazole, 15 mg or 30 mg. Within each study, subjects were randomized into two parallel cohorts consisting of 30 subjects per regimen, dispensed in opposing sequence over two periods separated by a 7-day washout period. Blood samples were collected on day 1 of both periods to determine the pharmacokinetic parameters.

RESULTS

Tmax occurred at 1.8 and 2.0 h with the 15-mg and 30-mg tablets, respectively. Dose proportional increases in Cmax, AUCt and AUC infinity were observed in the 15-mg and 30-mg groups. The terminal elimination half-lives (t1/2) were identical in both dose groups (1.18 h). Lansoprazole administered as the orally disintegrating tablet was bio-equivalent to the intact capsule formulation with respect to Cmax, AUCt and AUC infinity.

CONCLUSIONS

Lansoprazole orally disintegrating tablets, 15 mg and 30 mg, are bio-equivalent to the respective dose administered as the intact capsule. This novel dosage formulation represents an option for patients who have difficulty in swallowing oral agents.

Bioavailability of lansoprazole granules administered in juice or soft food compared with the intact capsule formulation

BACKGROUND

The ability to administer the contents of an encapsulated-dose formulation in liquids or soft foods without compromising drug bioavailability is highly desirable for patients who are unable to swallow or have difficulty swallowing.

OBJECTIVE

The purpose of this study was to compare the bioavailability of lansoprazole granules administered in 2 types of juice and a soft food with that of the intact capsule administered with water.

METHODS

Healthy adult volunteers were eligible for this single-center, Phase I, single-dose, randomized, open-label, 4-period crossover study. Subjects received the enteric-coated granular contents of a 30-mg lansoprazole capsule in 3 test regimens (in 180 mL of orange juice, 180 mL of tomato juice, or 1 tablespoon of strained pears, each followed by 180 mL of water) and 1 reference regimen (the 30-mg intact capsule with 180 mL of water). The regimens were rotated at > or = 6-day intervals so that each subject received all 4 regimens. Blood samples for pharmacokinetic analyses were obtained during the 12 hours after each regimen.

RESULTS

Twenty healthy adult volunteers (10 men, 10 women; mean age, 36 years [range, 19-53 years]) completed this study. Bioavailability of the 3 test regimens was assessed using the two 1-sided tests procedure for mean maximum plasma concentration and area under the plasma concentration-time curve (AUC) from time 0 through the last measurable concentration and AUC from time 0 to infinity. These results were compared with that of the intact capsule. This comparison indicated that the 90% CIs for all 3 test regimens were within the acceptable bioequivalence range of 0.80 to 1.25. Lansoprazole was well tolerated, with most of the adverse events being mild. Headache was the most frequently reported adverse event.

CONCLUSION

The results of this study indicate that the bioavailability of lansoprazole granules, when administered in orange juice, tomato juice, or a small amount of strained pears, was similar to that of the intact capsule in these healthy adult volunteers.

Acid suppression in healthy subjects following lansoprazole or pantoprazole

AIM

To compare the effect of lansoprazole, 30 mg once daily, with that of pantoprazole, 40 mg once daily, for the inhibition of gastric acid secretion.

METHODS

Two randomized, single-blind, two-way, crossover studies were conducted in 74 healthy male volunteers. Lansoprazole, 30 mg, or pantoprazole, 40 mg, was administered once daily for five consecutive days with at least a 2-week washout period between regimens. Ambulatory 24-h intragastric pH was recorded at baseline and on days 1 and 5 of each crossover treatment period.

RESULTS

On day 1 in both studies, lansoprazole, 30 mg, produced significantly higher mean 24-h intragastric pH values when compared to pantoprazole, 40 mg (3.78 vs. 3.08, P < 0.001, and 3.97 vs. 3.20, P < 0.001, in the first and second studies, respectively). In both studies, lansoprazole, 30 mg, produced significantly greater proportions of time that the intragastric pH was above 3, 4 and 5 when compared with pantoprazole, 40 mg (P < 0.005 in all comparisons). By treatment day 5 in the first study, lansoprazole, 30 mg, continued to produce a higher mean 24-h intragastric pH (4.15 vs. 3.91, P=0.014) and a significantly greater percentage of time that the intragastric pH was above 4 (63% vs. 56%, P=0.017) and 5 (41% vs. 30%, P < 0.001) when compared with pantoprazole, 40 mg. In the second study, the effects on intragastric pH were comparable between the two treatment groups. Headache was the most commonly reported adverse experience (nine lansoprazole-treated subjects, seven in the first study and two in the second study; six pantoprazole-treated subjects, five in the first study and one in the second study).

CONCLUSIONS

Lansoprazole, 30 mg once daily, produces a faster onset and greater degree of acid inhibition than pantoprazole, 40 mg once daily. The implications for these differences on symptom relief and healing of erosive oesophagitis should be explored.

Integrated acidity and rabeprazole pharmacology

BACKGROUND

Integrated gastric and oesophageal acidity can be calculated from measurements of gastric and oesophageal pH and used to quantify gastric and oesophageal acidity over time. Rabeprazole is a new proton pump inhibitor that is effective in treating gastro-oesophageal reflux disease (GERD).

AIM

To use measurement of integrated gastric and oesophageal acidity to determine the onset, duration and overall effect of rabeprazole in subjects with GERD.

METHODS

Subjects with GERD were required to have oesophageal pH less-than-or-equal 4 for at least 10% of a 24-h recording. Effects of 20 mg rabeprazole on 24-h gastric and oesophageal pH were measured on days 1 and 7 of dosing. Integrated gastric and oesophageal acidity were calculated from time-weighted average hydrogen ion concentrations at each second of the 24-h record.

RESULTS

At steady-state, 20 mg rabeprazole inhibited gastric acidity by 89% and oesophageal acidity by 95%. The first dose of rabeprazole inhibited gastric and oesophageal acidity by at least 70% of the steady-state effect. Oesophageal acidity could be divided into monophasic and biphasic patterns, and rabeprazole had different effects on oesophageal and gastric acidity in these two GERD subpopulations. The onset of action of the first dose of rabeprazole on gastric acidity was 4 h and on oesophageal acidity was 4 h in monophasic subjects and 7 h in biphasic subjects. Integrated acidity was more sensitive than time pH less-than-or-equal 4 in measuring the inhibitory actions of rabeprazole.

CONCLUSIONS

Integrated gastric and oesophageal acidity are quantitative measurements that provide useful and novel information regarding the pathophysiology of GERD as well as the impact of antisecretory agents such as rabeprazole.

A comparison of simplified lansoprazole suspension administered nasogastrically and pantoprazole administered intravenously: effects on 24-h intragastric pH

AIM

To compare the 24-h intragastric pH effects of simplified lansoprazole suspension, 30 mg, administered nasogastrically, with pantoprazole, 40 mg, administered intravenously.

METHODS

Thirty-six healthy adults were enrolled and given simplified lansoprazole suspension, 30 mg (nasogastrically), or pantoprazole, 40 mg (intravenously), once daily for five consecutive days in a cross-over fashion. Intragastric pH was monitored at baseline and on Days 1 and 5 of each treatment period. The pharmacokinetic parameters of lansoprazole and pantoprazole were also determined on Days 1 and 5.

RESULTS

No statistically significant changes in pharmacokinetic parameters occurred between Days 1 and 5 with either regimen, except for pantoprazole Cmax. On Days 1 and 5, significantly higher mean 24-h intragastric pH values were observed with 30 mg simplified lansoprazole suspension compared with 40 mg intravenous pantoprazole (Day 1, 3.13 vs. 2.67; Day 5, 3.95 vs. 3.61, respectively; P < 0.05). Additionally, 30 mg simplified lansoprazole suspension produced significantly (P < 0.05) higher percentages of time intragastric pH was above 3, 4, 5 or 6 as compared with 40 mg intravenous pantoprazole throughout Days 1 and 5.

CONCLUSIONS

A 30 mg dose of simplified lansoprazole suspension administered nasogastrically was consistently more effective at controlling intragastric pH than pantoprazole, 40 mg, administered intravenously.

Effects on 24-hour intragastric pH: a comparison of lansoprazole administered nasogastrically in apple juice and pantoprazole administered intravenously

OBJECTIVE

To compare the 24-h intragastric pH effects of lansoprazole, 30 mg administered nasogastrically, with pantoprazole, 40 mg administered i.v.

METHODS

Healthy adults were enrolled in an open label, two-way crossover, single-center study. Thirty milligrams of lansoprazole (administered nasogastrically in apple juice) or pantoprazole (i.v.) were administered once daily at 8:00 AM for 5 consecutive days with at least a 2-wk washout period between the regimens. Ambulatory 24-h intragastric pH was monitored at baseline and on days 1 and 5 of each treatment period. Blood specimens were collected on days I and 5 for pharmacokinetic parameter determinations.

RESULTS

Thirty-three adults completed both crossover periods, with the exception of one patient with a zero lansoprazole plasma concentration on day 1 of period 2. Lansoprazole, 30 mg per nasogastric tube, produced significantly higher mean 24-h intragastric pH values relative to pantoprazole, 40 mg i.v., on both day 1 (3.05 vs 2.76, p < 0.002) and day 5 (3.65 vs 3.45, p = 0.024). Lansoprazole sustained the intragastric pH above 3 (days 1 and 5), 4, and 5 (day 1) significantly longer relative to pantoprazole. Lansoprazole's time to the maximum observed concentration and area under the plasma concentration-time curve over the 24-h time interval increased significantly from day I to day 5 (1.7 h vs 2.0 h and 1865 ng x h/ml vs 2091 ng x h/ml, respectively), and a significant increase in half-life relative to day 1 (0.96 h) was observed on day 5 (1.03 h) during pantoprazole treatment.

CONCLUSION

Lansoprazole, 30 mg administered nasogastrically, effectively controls intragastric pH and is an alternative to i.v. pantoprazole in patients who are unable to swallow solid dosage formulations.

Pharmacological and pharmacodynamic essentials of H(2)-receptor antagonists and proton pump inhibitors for the practising physician

The suppression of gastric acid secretion with anti-secretory agents has been the mainstay of medical treatment for patients with acid-related disorders. Although the majority of Helicobacter pylori -related peptic ulcers can be healed with antibiotics, ulcer healing and symptom control can be significantly improved when antibiotics are given with anti-secretory agents, especially with a proton pump inhibitor. There is a dynamic relationship between the suppression of intragastric acidity and the healing of peptic ulcer and erosive oesophagitis and control of acid-related symptoms. The suppression of gastric acid secretion achieved with H(2)-receptor antagonists has, however, proved to be suboptimal for effectively controlling acid-related disorders, especially for healing erosive oesophagitis and for the relief of reflux symptoms. H(2)-receptor antagonists are also not effective in inhibiting meal-stimulated acid secretion, which is required for managing patients with erosive oesophagitis. Furthermore, the rapid development of tolerance to H(2)-receptor antagonists and the rebound acid hypersecretion after the withdrawal of an H(2)-receptor antagonist further limit their clinical use. Although low-dose H(2)-receptor antagonists are currently available as over-the-counter medications for self-controlling acid-related symptoms, their pharmacology and pharmacodynamics have not been well studied, especially in the self-medicating population. Proton pump inhibitors have been proved to be very effective for suppressing intragastric acidity to all known stimuli, although variations exist in the rapidity of onset of action and the potency of acid inhibition after oral administration at the approved therapeutic doses, which may have important clinical implications for the treatment of gastro-oesophageal reflux disease and perhaps for eradicating H. pylori infection when a proton pump inhibitor is given with antibiotics. Once-daily dosing in the morning is more effective than dosing in the evening for all proton pump inhibitors with respect to the suppression of intragastric acidity and daytime gastric acid secretion in particular, which may result from a better bio-availability being achieved with the morning dose. When higher doses are needed, these drugs must be given twice daily to achieve the optimal suppression of 24 hour intragastric acidity. Preliminary results have shown that esomeprazole, the optical isomer of omeprazole, given at 40 mg, is significantly more effective than omeprazole 40 mg, lansoprazole 30 mg or pantoprazole 40 mg for suppressing gastric acid secretion. However, more studies in different patient populations are needed to compare esomeprazole with the existing proton pump inhibitors with regard to their efficacy, cost-effectiveness and long-term safety for the management of acid-related disorders.

Pharmacodynamic modeling of lansoprazole using an indirect irreversible response model

A mechanism-based pharmacokinetic/pharmacodynamic model was used to assess lansoprazole effects on gastric pH. The irreversible inactivation of the H+/K+-ATPase enzyme by lansoprazole controls the secretion rate of H+ ions and gastric pH values. The basal circadian rhythm of gastric acid production was taken into account as well as the effects of food intake. A model was applied to multiple-dose data from a crossover study of four dosage regimens of lansoprazole in two groups of normal male subjects. Model parameters were estimated by nonlinear regression and were compared to historical values reported in the literature. The predicted mean gastric ion concentration was 23.2 mM (pH 1.6) with the peak time at 12.6 hours (8:30 p.m.), and the half-time for H+ removal from the stomach averaged 1.7 hours. The estimated half-life of gastric food removal was 0.8 hours. The rate constant for normal H+/K+-ATPase degradation was 0.045 h(-1). The pharmacodynamic parameter describing lansoprazole action on gastric acid secretion was the second-order enzyme inactivation constant, which averaged 0.16 microg(-1) x L x h(-1). The parameters obtained for both the baseline and drug treatment data were consistent with the literature and physiologically relevant with the exception of effective food volume, which was large presumably due to buffer effects. The model successfully incorporated the physiological regulation of gastric acid production, the effects of food on gastric acid, and the effects of multiple-dosing regimens of lansoprazole on gastric acid production to give reasonable profiles of gastric pH.

Duration of effect of lansoprazole on gastric pH and acid secretion in normal male volunteers

AIM

A double-blind, placebo-controlled study to assess the duration of effect of lansoprazole 30 mg o.m. on intragastric pH, acid secretion, gastrin levels, the potential for rebound acidity, and the relationship between gastric acid and drug pharmacokinetic parameters.

METHODS

Sixteen subjects were treated with lansoprazole 30 mg daily or placebo for 14 days, followed by a 7-day post-dosing period and a post-study evaluation on day 28. Ambulatory 24-h pH was recorded and pentagastrin-stimulated acid secretion measured. Plasma kinetics of lansoprazole were determined.

RESULTS

Mean intragastric pH in the lansoprazole group increased significantly (P < 0.05) from baseline to day 14 compared to placebo. After cessation of treatment, secretory activity, as measured by intragastric pH, basal acid output and stimulated acid output, returned to baseline in 2 to 4 days without any overshoot, indicating the absence of acid rebound. Lansoprazole's terminal disposition half-life was 1.11 h. Mean pH and serum gastrin returned to baseline with half-lives of 22 and 19 h, respectively.

CONCLUSIONS

Lansoprazole 30 mg daily significantly increases mean intragastric pH without producing acid rebound. Regeneration of acid production depends primarily on de novo synthesis of the acid pump.

Standard-dose lansoprazole is more effective than high-dose ranitidine in achieving endoscopic healing and symptom relief in patients with moderately severe reflux oesophagitis. The Dutch Lansoprazole Study Group

BACKGROUND

In the treatment of reflux oesophagitis, H2-receptor antagonists are still widely used in spite of the apparent higher efficacy of proton pump inhibitors. In an attempt to compensate for the lower efficacy, H2-receptor antagonists are now increasingly being used at a higher dose.

OBJECTIVE

To assess whether or not standard-dose lansoprazole (30 mg o.d.) is more effective than high-dose ranitidine (300 mg b.d.) in moderately severe reflux oesophagitis (grades II-III).

METHODS

Lansoprazole or ranitidine was given to 133 patients for 4-8 weeks in a double-blind, randomized, parallel group, multicentre trial.

RESULTS

The percentage of patients with endoscopically-verified healing was significantly higher on lansoprazole than on ranitidine both after 4 weeks (79% vs. 42%) and 8 weeks (91% vs. 66%), though smoking had a negative impact on oesophagitis healing with lansoprazole. Heartburn, retrosternal pain and belching improved significantly better with lansoprazole than with ranitidine, as did the patient-rated overall symptom severity. Relief of heartburn appeared somewhat faster with ranitidine, but was more pronounced with lansoprazole. The number of patients with adverse events was similar in both treatment groups.

CONCLUSION

Standard-dose lansoprazole is better than high-dose ranitidine in moderately severe reflux oesophagitis.

Effect of 7-day therapy with different doses of the proton pump inhibitor lansoprazole on the intragastric pH in healthy human subjects

BACKGROUND

Systematic, randomized, and controlled studies on the effect of low to high doses of the proton pump inhibitor lansoprazole on intragastric acidity and plasma gastrin levels have not previously been performed.

METHODS

We investigated the effect of 7-day therapy with different doses of lansoprazole (15 mg once or twice daily, 30 mg once or twice daily, and 15 mg three times daily) on intragastric acidity and meal-stimulated daytime plasma gastrin levels in 12 healthy Helicobacter pylori-negative human subjects in a randomized, double-blind, placebo-controlled, 6-way crossover study. On days 1, 2, and 7 of the study 24-h intragastric pH-metry and 12-h integrated daytime plasma gastrin determinations were done.

RESULTS

Lansoprazole in a dose regimen of 1 x 30 mg/day, 3 x 15 mg/daily, and 2 x 30 mg/day significantly (P < 0.05) increased the intragastric 24-h median pH on days 1, 2, and 7 of therapy as compared with placebo. Lansoprazole in doses of 1 x 15 mg/day and 2 x 15 mg/day significantly increased the intragastric 24-h median pH on days 2 and 7 but not on day 1 of therapy. Doses of 3 x 15 mg and 2 x 30 mg lansoprazole daily significantly increased the intragastric 24-h median pH on days 2 and 7 of treatment as compared with 1 x 30 mg lansoprazole daily. Except for 1 x 15 mg lansoprazole on day 1 of therapy, all given dose regimens of lansoprazole (15-60 mg/day) significantly (P < 0.05) stimulated the 12-h integrated meal-stimulated daytime plasma gastrin response (pM x min) on days 1, 2, and 7 of therapy as compared with placebo.

CONCLUSION

A dose of 1 x 30 mg/day is nearly as potent as higher dose regimens of lansoprazole. Thus it most likely is the optimum dose for therapy of gastric and duodenal peptic lesions. A dose of 1 x 15 mg lansoprazole daily is a potent inhibitor of gastric acid output and could be a therapeutic dose for prevention of peptic lesions (that is, reflux oesophagitis or ulcers).

Influence of pH on metabolism and urease activity of Helicobacter pylori

BACKGROUND & AIMS

The metabolic and urease responses of Helicobacter pylori to variations in gastric acidity are unknown. The aim of this study was to determine effects of changes of environmental pH on metabolism, urease activity, and survival of H. pylori in an unbuffered environment.

METHODS

Bacterial metabolism and urease activity were determined by measuring pH changes in perfused microphysiometer chambers over a pH range from 2.5 to 9.0 with or without urea and survival by restoration of metabolism at pH 7.4.

RESULTS

Glucose metabolism by acid-adapted H. pylori occurred at a perfusion pH between 3.5 and 8.6 and was highest between 7.4 and 8.2. Metabolism was irreversibly inhibited at pH <3.5 or >8.6. In the presence of 2.5 mmol/L urea, the chamber pH increased to about 6.2 during perfusion between pH 5.5 and 4.0. At pH 4.0 and below, urease activity increased several-fold without change of chamber pH. Urea in the perfusate enabled retention of metabolism after acid exposure but was toxic at pH 7.4.

CONCLUSIONS

The metabolic range of acid-adapted H. pylori is between an environmental pH of 3.5 and 8.6. Extracellular pH-regulated internal urease activity allows metabolism in the pH range between 4.0 and 2. 5 by maintaining periplasmic pH at 6.2. The organism is an acid-tolerant neutralophile due to internal urease activity.