Pharmacodynamic effects of single doses of rabeprazole 20 mg and pantoprazole 40 mg in patients with GERD and nocturnal heartburn

The pharmacokinetics, pharmacodynamics and safety of oral doses of ilaprazole 10, 20 and 40 mg and esomeprazole 40 mg in healthy subjects: a randomised, open-label crossover study

BACKGROUND

Ilaprazole, a proton pump inhibitor (PPI) currently in clinical use, may provide improved acid suppression vs. other PPIs.

AIM

To compare the pharmacodynamic and pharmacokinetic profiles of ilaprazole and esomeprazole.

METHODS

A phase 1, randomised, open-label, single-centre, 4-period crossover study was conducted in 40 healthy volunteers. Ilaprazole 10, 20 or 40 mg or esomeprazole 40 mg was administered once daily for 5 days with ≥5-day washout intervals. Pharmacokinetic blood samples and intragastric pH measurements were collected at scheduled timepoints for 24 h after dosing on Days 1 and 5.

RESULTS

Esomeprazole 40 mg provided significantly better pH control during the initial hours (0-4 h) after a single dose, but ilaprazole (particularly 20 and 40 mg) provided significantly better pH control for the entire 24-h period and during evening and overnight hours after single and multiple doses. Increasing ilaprazole doses resulted in dose-proportional increases in peak plasma concentration and area under the plasma concentration vs. time curve following single and multiple doses. Ilaprazole was safe and generally well tolerated; an unexpectedly high incidence of allergic eye and skin reactions were observed but were not specific to any dosing regimen. Plasma gastrin concentrations did not increase proportionately with increasing ilaprazole dose.

CONCLUSIONS

Ilaprazole provided significantly better pH control over 24 h and during evening and overnight hours compared with esomeprazole in healthy volunteers, which may translate to greater relief of night-time heartburn in the clinical setting for patients with gastric acid-related disorders.

On-demand proton pump inhibitory treatment in overweight/obese patients with gastroesophageal reflux disease: are there pharmacodynamic arguments for using higher doses?

BACKGROUND

Increased body mass index (BMI) is associated with a higher risk of gastroesophageal reflux disease (GORD).

AIM

To investigate whether overweight/obesity affects proton pump inhibitor pharmacodynamics when used in a single dose in patients with GORD.

METHODS

Post hoc analyses by patient BMI were performed on data from two single-center, double-blind, single-dose, crossover studies comparing the pharmacodynamics of rabeprazole 20 mg and pantoprazole 40 mg in GORD patients with a history of nocturnal heartburn. The primary endpoint was the mean percentage of time with intragastric pH >4 between lean and overweight/obese patients (BMI <25 and ≥25).

RESULTS

24 h baseline intragastric pH values were not different between BMI groups. The pharmacodynamic effects of both proton pump inhibitors were not significantly different between BMI groups, and no evidence was found for an interaction between BMI and treatment. As compared with pantoprazole, rabeprazole showed a significantly greater effect on the antisecretory response for both BMI groups.

CONCLUSIONS

Overweight/obesity in GORD patients does not appear to affect the antisecretory efficacy of a single dose of rabeprazole and pantoprazole. These data do not support adapting the dosage of rabeprazole and pantoprazole according to BMI in GORD patients when administered as an on-demand therapy schedule.

In vitro effect of pantoprazole on lower esophageal sphincter tone in rats

AIM: To investigate the in vitro effects of pantoprazole on rat lower esophageal sphincter (LES) tone.

METHODS: Rats weighing 250-300 g, provided by the Yeditepe University Experimental Research Center (YÜDETAM), were used throughout the study. They were anesthetized before decapitation. LES tissues whose mucosal lining were removed were placed in a standard 30-mL organ bath with a modified Krebs solution and continuously aerated with 95% oxygen-5% carbon dioxide gas mixture and kept at room temperature. The tissues were allowed to stabilize for 60 min. Subsequently, the contractile response to 10^-6 mol/L carbachol was obtained. Different concentrations of freshly prepared pantoprazole were added directly to the tissue bath to generate cumulative concentrations of 5 × 10^-6 mol/L, 5 × 10^-5 mol/L, and 1.5 × 10^-4 mol/L. Activities were recorded on an online computer via a 4-channel transducer data acquisition system using the software BSL PRO v 3.7, which also analyzed the data.

RESULTS: Pantoprazole at 5 × 10^-6 mol/L caused a small, but statistically insignificant, relaxation in the carbachol-contracted LES (2.23% vs 3.95%). The 5 × 10^-5 mol/L concentration, however, caused a significant relaxation of 10.47% compared with the control. 1.5 × 10^-4 mol/L concentration of pantoprazol caused a 19.89% relaxation in the carbachol contracted LES (P < 0.001).

CONCLUSION: This is the first study to demonstrate that pantoprazole has a relaxing effect in isolated LESs. These results might have significant clinical implications for the subset of patients using proton pump inhibitors who do not receive full symptomatic alleviation from gastroesophageal reflux disease.

Rabeprazole: a review of its use in the management of gastric acid-related diseases in adults

Rabeprazole (Aciphex, Alfence, Pariet) is a proton pump inhibitor (PPI) used for the treatment of adults with conditions requiring a reduction of gastric acid secretion such as erosive or ulcerative gastro-oesophageal reflux disease (GORD), non-erosive reflux disease (NERD), duodenal and gastric ulcers, and pathological hypersecretory conditions including Zollinger-Ellison syndrome (ZES). It is also used as part of combination therapy for the eradication of Helicobacter pylori, a pathogen frequently implicated in the development of gastric and duodenal ulcers. Rabeprazole has a well established efficacy and safety profile in the treatment of gastric acid-related diseases. Rabeprazole is a useful, well tolerated and cost-effective option for the treatment of GORD, NERD, peptic ulcer and other gastric acid-related diseases (including ZES), and provides an appropriate alternative to other currently available PPIs, with the added benefits of having a consistent efficacy profile and low drug interaction potential due to its predominantly nonenzymatic metabolism.

Additional bedtime H2-receptor antagonist for the control of nocturnal gastric acid breakthrough

BACKGROUND

Nocturnal gastric acid breakthrough (NAB) is defined as intragastric pH<4 for more than one continuous hour overnight. Adding H(2)-receptor antagonists (H2RAs) at bedtime to high-dose proton pump inhibitors is likely to enhance nocturnal gastric pH control and decrease nocturnal gastric acid breakthrough.

OBJECTIVES

To assess the effectiveness of additional bedtime H2-receptor antagonists in suppressing nocturnal gastric acid breakthrough and the incidence of adverse effects.

SEARCH STRATEGY

We identified eligible trials by searching The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 4, 2008), MEDLINE (1966-August 2008), EMBASE (1980-August 2008) and CINAHL (1982-August 2008). We re-ran the search on CENTRAL (The Cochrane Library Issue 4, 2008), and in MEDLINE, EMBASE and CINAHL in June 2004, July 2005, August 2006 and August 2008.

SELECTION CRITERIA

All randomized controlled trials evaluating H2-receptor antagonists for the control of nocturnal gastric acid breakthrough were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two reviewers have independently selected the trials to be included in the review according to the pre-stated eligibility criteria. Disagreements were resolved by a third reviewer. If the data could not be pooled for meta-analysis, a narrative description was provided.

MAIN RESULTS

8 small randomized controlled trials were included for meta-analysis. The results show that additional bedtime H2RAs can decrease the prevalence rate of nocturnal gastric acid breakthrough. The results of the analyses for secondary outcomes show that additional bedtime H2RAs can decrease the percentage of time during which pH is less than 4.0 inside the stomach and promote median intragastric pH.

AUTHORS' CONCLUSIONS

We can conclude no implications for practice at this stage. Appropriately designed large-scale randomized controlled trials with long-term follow-up are needed to determine the effects of additional bedtime H2RAs in suppressing nocturnal gastric acid breakthrough.

The relationship between gastroesophageal reflux disease and sleep

Recent studies demonstrate a bidirectional relationship between gastroesophageal reflux disease (GERD) and sleep in which nighttime reflux leads to sleep deprivation and sleep deprivation can exacerbate GERD by enhancing perception of intraesophageal stimuli. Current treatment primarily focuses on reducing nighttime reflux, thus improving sleep quality. Future studies are needed to further explore the relationship between GERD and sleep and the potential of novel therapeutic options to interrupt the vicious cycle between them.

Relative potency of proton-pump inhibitors-comparison of effects on intragastric pH

AIM

Comparative potency of proton-pump inhibitors (PPIs) is an important clinical issue. Most available trials have compared the different PPIs at one or a few selected specific dosages, making it difficult to derive quantitative equivalence dosages. Here we derived PPI dose equivalents based on a comprehensive assessment of dose-dependent effects on intragastric pH.

METHODS

All available clinical studies reporting the effects of PPIs on mean 24-h intragastric pH were sought from electronic databases including Medline. Studies included were restricted to those targeting the Caucasian population, and healthy volunteers or gastroesophageal reflux disease (GERD) patients. The dose-effect relationships for mean 24-h intragastric pH and for percentage of time with pH > 4 in 24 h were analyzed for each PPI using pharmacodynamic modeling with NONMEM and a model integrating all available data.

RESULTS

Fifty-seven studies fulfilled the inclusion criteria. Based on the mean 24-h gastric pH, the relative potencies of the five PPIs compared to omeprazole were 0.23, 0.90, 1.00, 1.60, and 1.82 for pantoprazole, lansoprazole, omeprazole, esomeprazole, and rabeprazole, respectively. Compared with healthy volunteers, patients with GERD needed a 1.9-fold higher dose and Helicobacter pylori-positive individuals needed only about 20% of the dose to achieve a given increase in mean 24-h intragastric pH.

CONCLUSION

The present meta-analysis provides quantitative estimates on clinical potency of individual PPIs that may be helpful when switching between PPIs and for assessing the cost-effectiveness of specific PPIs. However, our estimates must be viewed with caution because only a limited dose range has been tested and not exactly the same study conditions were applied for the different substances.

Proton pump inhibitors: an update of their clinical use and pharmacokinetics

BACKGROUND

Proton pump inhibitors (PPIs) represent drugs of first choice for treating peptic ulcer, Helicobacter pylori infection, gastrooesophageal reflux disease, nonsteroidal anti-inflammatory drug (NSAID)-induced gastrointestinal lesions (complications), and Zollinger-Ellison syndrome.

RESULTS

The available agents (omeprazole/esomeprazole, lansoprazole, pantoprazole, and rabeprazole) differ somewhat in their pharmacokinetic properties (e.g., time-/dose-dependent bioavailability, metabolic pattern, interaction potential, genetic variability). For all PPIs, there is a clear relationship between drug exposure (area under the plasma concentration/time curve) and the pharmacodynamic response (inhibition of acid secretion). Furthermore, clinical outcome (e.g., healing and eradication rates) depends on maintaining intragastric pH values above certain threshold levels. Thus, any changes in drug disposition will subsequently be translated directly into clinical efficiency so that extensive metabolizers of CYP2C19 will demonstrate a higher rate of therapeutic nonresponse.

CONCLUSIONS

This update of pharmacokinetic, pharmacodynamic, and clinical data will provide the necessary guide by which to select between the various PPIs that differ-based on pharmacodynamic assessments-in their relative potencies (e.g., higher doses are needed for pantoprazole and lansoprazole compared with rabeprazole). Despite their well-documented clinical efficacy and safety, there is still a certain number of patients who are refractory to treatment with PPIs (nonresponder), which will leave sufficient space for future drug development and clinical research.

Rabeprazole: a second-generation proton pump inhibitor in the treatment of acid-related disease

Rabeprazole is a proton pump inhibitor (PPI) presenting a very advantageous pharmacodynamic and pharmacokinetic profile over older PPIs. In particular, this drug has a very fast onset of action, due to a short activation time and a very high pKa, and may therefore be defined as a 'second generation' PPI. The aim of this article is to provide an update on the pharmacology and clinical profile of rabeprazole and its use in acid-related disorders, with a particular focus on its role in gastroesophageal reflux disease; in the treatment and prevention of duodenal and gastric ulcers and Zollinger-Ellison syndrome; in the therapy of the extraesophageal manifestations of gastroesophageal reflux disease (in particular the respiratory and ear, nose and throat ones); and in the eradication of Helicobacter pylori.