Effect of frequent dosing of an oral proton pump inhibitor on intragastric pH

Pharmacologic treatment of peptic ulcer bleeding

Over the last 3 decades, there has been extensive clinical research on the pharmacologic treatment of peptic ulcer bleeding. A critical review of randomized controlled trials and meta-analyses reveals insufficient evidence to recommend histamine-2 receptor antagonists (H(2)RAs), somatostatin, octreotide, or tranexamic acid in the routine management of patients with peptic ulcer bleeding. In contrast, there is good-quality evidence for recommending proton-pump inhibitor (PPI) treatment for patients with peptic ulcer bleeding. PPI treatment, compared with an H(2)RA or placebo, reduces rebleeding and the need for surgical intervention and, in patients with high-risk endoscopic stigmata, also reduces all-cause mortality. Patients with ulcers that demonstrate only low-risk endoscopic stigmata (clean base or flat pigmented spot) can be treated with an oral PPI at double the standard clinical dose. Patients with ulcers that demonstrate high-risk endoscopic stigmata (spurting, oozing, or nonbleeding visible vessel) should receive high-dose intravenous PPI treatment following appropriate endoscopic hemostatic treatment. The currently recommended dose is an initial intravenous bolus equivalent to 80 mg of omeprazole followed by an intravenous infusion equivalent to 8.0 mg/h of omeprazole for up to 72 hours. A switch to high-dose oral PPI treatment may be appropriate before completion of a 72-hour treatment period in some patients whose clinical status stabilizes early. Once the initial bleeding episode has been dealt with, patients will require standard pharmacologic treatment to heal the ulcer and prevent recurrence.

Esomeprazole for the treatment of peptic ulcer bleeding

Peptic ulcer bleeding is the most common cause of acute bleeding in the upper GI tract. The incidence of peptic ulcer bleeding has slowly decreased and endoscopic treatment options have improved; nevertheless, it remains a very common condition with a 7-15% mortality. Acidic environments have a negative effect on hemostasis. Therefore, acid inhibitors have been applied in the adjuvant treatment of peptic ulcer bleeding, both in preventing rebleeding and in treating the underlying cause. This requires profound acid suppressive therapy aiming for a rapid onset of effect and a persistent intragastric pH above 6. This can only be achieved by proton pump inhibitors (PPIs). Esomeprazole is the S-isomer of omeprazole, and the first PPI to consist of only the active isomer. A number of studies have compared esomeprazole with other PPIs, demonstrating a faster and more persistent increase in intragastric pH with the use of esomeprazole than with other agents. Continuous high-dose intravenous treatment with esomeprazole decreases rebleeding, surgery, transfusion rates and hospital days in peptic ulcer bleeding.

Intravenous proton pump inhibitors: an evidence-based review of their use in gastrointestinal disorders

Conditions requiring inhibition of acid secretion, such as gastro-oesophageal reflux disease or peptic ulcers, are very common and their prevalence is expected to rise as they are seen predominantly in the elderly. The general basis of treatment with antisecretory agents is to maintain gastric pH >4 for a substantial proportion of the 24-hour cycle. Among the drugs available to inhibit acid secretion, proton pump inhibitors (PPIs) have been shown to have the best benefit-risk ratio and have been used widely. Intravenous administration of a PPI provides gastric acid suppression faster than oral administration does. Whereas some indications for the use of intravenous PPIs are widely known, mostly for acute management of peptic ulcer bleeding, there are some controversies surrounding their use in other conditions such as stress-induced mucosal damage. There is still a need to define the best schedule for intravenous PPI administration (i.e. bolus infusion or constant infusion), the optimal time to switch from intravenous to oral administration and the choice of which agent is best. In most of the clinical scenarios where PPIs are recommended, they can be administered via either oral or enteral routes, unless the patient is nil by mouth. Since there are no head-to-head comparisons of the different intravenous PPIs available worldwide (omeprazole, lansoprazole, pantoprazole and esomeprazole), the rule might be to choose the drug with the best proven efficacy in each specific condition. Indeed, the key difference between them, the ability to reach and to maintain a threshold gastric pH, might not necessarily translate into clinically significant differences.

Proton pump inhibitors: actions and reactions

Proton pump inhibitors are the second most commonly prescribed drug class in the United States. The increased utilization of PPIs parallels the rising incidence of reflux disease. Owing to their clinical efficacy and relative lack of tachyphylaxis, PPIs have largely displaced H-2 receptor antagonists in the treatment of acid peptic disorders. The elevation of intragastric pH and subsequent alterations of gastric physiology induced by PPIs may yield undesired effects within the upper GI tract. The ubiquity of the various types of H(+), K(+)-ATPase could also contribute to non-gastric effects. PPIs may influence physiology in other ways, such as inducing transepithelial leak.

Intragastric pH with oral vs intravenous bolus plus infusion proton-pump inhibitor therapy in patients with bleeding ulcers

BACKGROUND & AIMS

Intravenous bolus plus infusion proton pump inhibitor (PPI) therapy is recommended for patients with bleeding ulcers and higher risk stigmata. If frequent oral dosing of PPIs provided similar antisecretory effect, this might be preferred based on ease and cost.

METHODS

Patients presenting with overt bleeding due to ulcers had intragastric pH probes placed after endoscopy and baseline pH recorded. They were randomly assigned to intravenous lansoprazole (90-mg bolus followed by 9-mg/h infusion) or oral lansoprazole (120-mg bolus followed by 30 mg every 3 hours). pH was recorded for 24 hours.

RESULTS

Intragastric pH was > 6 for 67.8% of the study period with intravenous PPI (n = 32) and 64.8% with oral PPI (n = 34): difference, 3.0%; 95% confidence interval (CI): -9.2% to 15.2%. Intragastric pH was > 6 for > 60% of the study period in 22 (68.8%) patients receiving intravenous and 22 (64.7%) patients receiving oral PPI: difference, 4.0%; 95% CI: -18.7% to 26.8%. At 1 hour, mean pHs for intravenous vs oral were 5.3 +/- 0.4 vs 3.3 +/- 0.4, respectively (difference, 2.0; 95% CI: 0.8-3.1; P = .001). At > or = 1.5 hours, 95% CIs of the differences for all hourly mean pHs included zero. Mean pH rose above 6 after 2-3 hours of intravenous PPI and 3-4 hours of oral PPI.

CONCLUSIONS

Frequent oral PPI may be able to replace the currently recommended intravenous bolus plus infusion PPI therapy in patients with bleeding ulcers, although the possibility that intravenous PPIs are superior cannot be definitively excluded given our relatively wide confidence intervals. Intravenous PPI provides more rapid increase in pH, reaching mean pH of 6 approximately 1 hour sooner than oral PPI.

Identification of the time-point which gives a plasma rabeprazole concentration that adequately reflects the area under the concentration-time curve

OBJECTIVE

The purpose of this study is to evaluate whether a simple formula using limited blood samples can predict the area under the plasma rabeprazole concentration-time curve (AUC) in co-administration with CYP inhibitors.

METHODS

A randomized double-blind placebo-controlled crossover study design in three phases was conducted at intervals of 2 weeks. Twenty-one healthy Japanese volunteers, including three CYP2C19 genotype groups, took a single oral 20-mg dose of rabeprazole after three 6-day pretreatments, i.e., clarithromycin 800 mg/day, fluvoxamine 50 mg/day, and placebo. Prediction formulas of the AUC were derived from pharmacokinetics data of 21 subjects in three phases using multiple linear regression analysis. Ten blood samples were collected over 24 h to calculate AUC. Plasma concentrations of rabeprazole was measured by an HPLC-assay (l.l.q.=1 ng/ml).

RESULTS

The AUC was based on all the data sets (n=63). The linear regression using two points (C3 and C6) could predict AUC(0-infinity) precisely, irrespective of CYP2C19 genotypes and CYP inhibitors (AUC(0-infinity)=1.39xC3+7.17xC6+344.14, r (2)=0.825, p<0.001).

CONCLUSION

The present study demonstrated that the AUC of rabeprazole can be estimated by the simple formula using two-point concentrations. This formula can be more accurate for the prediction of AUC estimation than that reflected by CYP2C19 genotypes without any determination, even if there are significant differences for the CYP2C19 genotypes. Therefore, this prediction formula might be useful to evaluate whether CYP2C19 genotypes really reflects the curative effect of rabeprazole.