Optimizing acid suppression for treatment of acid-related diseases

The gastroprotective effect of Yucca filamentosa standardized crude leaves extract versus its nano-cubosomal formulation in ethanol-induced gastric injury

Yucca filamentosa (YF) is widely used in folk medicine for its anti-inflammatory effects. Our study aimed to evaluate the chemical profile of YF extracts. Additionally, the gastroprotective efficacy of its crude leaf extract and nano-cubosomal formulation was assessed in a rat model of ethanol-induced gastric injury by altering the HMGB-1/RAGE/TLR4/NF-κB pathway. The phytochemical composition of YF was investigated using FTIR spectroscopy and LC-MS/MS techniques. Standardization was further accomplished using HPLC. Rats were treated orally with yucca crude extract or its nano-cubosomal formulation at doses of 25, 50, and 100 mg/kg. Famotidine (50 mg/kg, IP) was used as a reference drug. After 1 h, rats were administered ethanol (1 ml, 95 %, orally). One hour later, the rats were sacrificed, and the serum was separated to determine TNF-α and IL-6 levels. Stomachs were excised for the calculation of the ulcer index and histopathological examinations. Stomach tissue homogenate was used to determine MDA and catalase levels. Additionally, the expression levels of HMGB-1/RAGE/TLR4/NF-κB were assessed. Phytochemical analysis confirmed the predominance of steroidal saponins, sucrose, organic and phenolic acids, and kaempferol. The nano-cubosomal formulation demonstrated enhanced gastroprotective, anti-oxidant, and anti-inflammatory efficacy compared to the crude extract at all tested doses. The most prominent effect was observed in rats pretreated with the YF nano-cubosomal formulation at a dose of 100 mg/kg, which was similar to normal control and famotidine-treated rats. Our results highlighted the enhanced gastroprotective impact of the yucca nano-cubosomal formulation in a dose-dependent manner. This suggests its potential use in preventing peptic ulcer recurrence.

Common and disparate clinical presentations and mechanisms in different eosinophilic gastrointestinal diseases

Eosinophilic gastrointestinal diseases (EGIDs) are a group of diseases characterized by selective eosinophil infiltration of the gastrointestinal (GI) tract in the absence of other causes of eosinophilia. These diseases are generally driven by type 2 inflammation, often in response to food allergen exposure. Among all EGIDs, the clinical presentation often includes a history of atopic disease with a variety of GI symptoms. EGIDs are traditionally separated into eosinophilic esophagitis (EoE) and non-EoE EGIDs. EoE is relatively better understood and now associated with clinical guidelines and 2 US Food and Drug Administration-approved treatments, whereas non-EoE EGIDs are rarer and less well-understood diseases without US Food and Drug Administration-approved treatments. Non-EoE EGIDs are further subclassified by the area of the GI tract that is involved; they comprise eosinophilic gastritis, eosinophilic enteritis (including eosinophilic duodenitis), and eosinophilic colitis. As with other GI disorders, the disease presentations and mechanisms differ depending on the involved segment of the GI tract; however, the differences between EoE and non-EoE EGIDs extend beyond which GI tract segment is involved. The aim of this article is to summarize the commonalities and differences between the clinical presentations and disease mechanisms for EoE and non-EoE EGIDs.

Proton pump inhibitors use and the risk of fatty liver disease: A nationwide cohort study

BACKGROUND AND AIM

Proton pump inhibitor (PPI)-induced hypochondria can change the composition of the gut microbiota, inducing overgrowth of small bowel bacteria, which has been suggested to promote the development of fatty liver disease through the gut-liver axis. In this study, we aimed to investigate the association between PPI use and the risk of fatty liver disease.

METHODS

A retrospective cohort study was conducted using the Korean National Health Insurance Service-National Sample Cohort, a nationwide population-based representative sample, from January 1, 2002, to December 31, 2015. PPI use was identified from treatment claims and considered as a time-varying variable.

RESULTS

During 1 463 556 person-years of follow-up, 75 727 patients had at least one PPI prescription, and 3735 patients developed fatty liver disease. The hazard ratio for fatty liver disease comparing PPI users with non-PPI users was 1.68 (95% confidence interval, 1.61-1.75). When adjusted for multiple confounders, including age, sex, body mass index, smoking, alcohol intake, exercise, income level, and comorbidities, the association was still significant (hazard ratio, 1.50; 95% confidence interval, 1.44-1.57). After considering the amounts of PPIs stratified by cumulative defined daily dose, the dose-response effect was observed until 180 days. Subgroup analysis also revealed that PPI use was correlated to an increased risk of fatty liver disease.

CONCLUSIONS

This current national wide cohort study suggests that PPI use was associated with an increased risk of fatty liver disease compared with non-use of PPIs. Clinicians should consider fatty liver as a potential risk when prescribing PPI.

Randomised clinical trial: tegoprazan, a novel potassium-competitive acid blocker, or lansoprazole in the treatment of gastric ulcer

BACKGROUND

Tegoprazan is a novel potassium-competitive acid blocker for the treatment of acid-related disorders.

AIMS

To assess whether tegoprazan is non-inferior to lansoprazole in terms of efficacy and safety in patients with gastric ulcers.

METHODS

In this phase 3, double-blind, active control, multicentre study, 306 gastric ulcer patients were randomised to one of three treatment groups: tegoprazan 50 mg, tegoprazan 100 mg and lansoprazole 30 mg once daily for 4 or 8 weeks. The primary endpoint was the cumulative proportion of patients with healed ulcers confirmed by endoscopy up to 8 weeks from treatment initiation. Symptoms and safety were assessed.

RESULTS

In the full analysis set, the cumulative healing rates at week 8 were 94.8% (91/96) for the tegoprazan 50 mg, 95.0% (94/99) for the tegoprazan 100 mg and 95.7% (89/93) for the lansoprazole 30 mg groups. At week 4, the respective healing rates were 90.6% (87/96), 91.9% (91/99), and 89.2% (83/93). In per protocol analysis, 4-week healing rates were 95.4% (84/88), 94.6% (88/93) and 92.9% (79/85) for tegoprazan 50 mg, tegoprazan 100 mg and lansoprazole 30 mg, respectively. Both doses of tegoprazan were non-inferior to lansoprazole in ulcer healing at 4 and 8 weeks. The incidence of drug-related treatment-emergent adverse events did not differ among groups. The increase in serum gastrin concentration was not higher in tegoprazan-treated patients than in lansoprazole-treated patients.

CONCLUSIONS

Tegoprazan 50 or 100 mg were not inferior to lansoprazole 30 mg once daily in the treatment of gastric ulcers.

Proton Pump Inhibitors Prevent Gastric Antral Ulcers Induced by NSAIDs via Activation of Capsaicin-Sensitive Afferent Nerves in Mice

BACKGROUND/AIMS

We examined the effects of proton pump inhibitors (PPIs) on gastric antral ulcers induced by non-steroidal anti-inflammatory drugs in re-fed mice and the role of capsaicin-sensitive afferent nerves (CSANs) in the protective effects of PPIs on the antral mucosa.

METHODS

Male mice were administered indomethacin after 2 h of re-feeding of diet after a 24-h fast, and gastric lesions were examined 24 h after indomethacin dosing. The effects of PPIs (lansoprazole and omeprazole), histamine H₂-receptor antagonists (H₂-RAs, famotidine, ranitidine), capsaicin and misoprostol on the formation of antral ulcers induced by indomethacin were examined. Functional ablation of CSANs was caused by pretreatment of mice with a high dose of capsaicin.

RESULTS

Indomethacin produced lesions selectively in the gastric antrum in re-fed conditions. Formation of antral ulcers was not affected by H₂-RAs, but inhibited by PPIs, capsaicin and misoprostol. The anti-ulcer effect of lansoprazole was 30 times stronger than that of omeprazole. Antral ulcers induced by indomethacin were markedly aggravated in mice with ablated CSANs. The effects of PPIs and capsaicin on ulcer formation were inhibited by ablation of CSANs, pretreatment with a capsaicin receptor antagonist (capsazepine/ruthenium red) and an inhibitor of nitric oxide synthesis (L-NAME). However, the inhibitory effect of misoprostol was not prevented by the ablation of CSANs or drugs.

CONCLUSIONS

The results suggested that CSANs play an important role in protection of the antral mucosa and that both lansoprazole and omeprazole are capable of preventing NSAID-induced antral ulcers by activating CSANs.

A comparison between the combined effect of calcium carbonate with sucroferric oxyhydroxide and other phosphate binders: an in vitro and in vivo experimental study

Background

Approximately 30% of patients on dialysis received combination therapy for their phosphate binder prescription; however, few studies for combined effects of phosphate binders are reported. For the purpose of evaluating the efficacy of combination therapy, we compared the efficacy of sucroferric oxyhydroxide (PA21) combined with calcium carbonate with that of lanthanum carbonate hydrate, sevelamer hydrochloride, and ferric citrate hydrate combined with calcium carbonate.

Methods

For in vitro studies, calcium carbonate and the other phosphate binders alone or in combination were stirred in phosphate solution at pH 2–8 for 2 h. After centrifuging the suspension, the phosphorus level in the supernatant was determined. For in vivo studies, rats were orally administered calcium carbonate and the other phosphate binders (except for sevelamer hydrochloride) alone or in combination, followed by oral administration of phosphate solution adjusted to pH 2 or 7. Serum samples were collected from the rats at predetermined timepoints and the serum phosphorus levels were determined and analyzed using a two-way analysis of variance.

Results

In the in vitro study, the measured phosphate-binding capacity of combining sevelamer hydrochloride, PA21, and lanthanum carbonate hydrate with calcium carbonate was approximately equal to or greater than the theoretical values under most conditions. Furthermore, these combined effects were insensitive to pH in that order. The measured phosphate-binding capacity of ferric citrate hydrate combined with calcium carbonate was smaller than the theoretical values, and the combination did not exhibit efficacy under any of the tested conditions. In the in vivo study, the combined effect of PA21 and calcium carbonate at both pH values and that of lanthanum carbonate hydrate and calcium carbonate at pH 2 were additive. In contrast, the combined effect of lanthanum carbonate hydrate and calcium carbonate at pH 7 and that of ferric citrate hydrate and calcium carbonate at pH 2 were antagonistic.

Conclusions

These results suggest that coadministration of PA21 and calcium carbonate showed good and relatively stable efficacy throughout the range of the gastrointestinal pH and that combining lanthanum carbonate hydrate and ferric citrate hydrate with calcium carbonate may not produce the expected efficacy under certain conditions.

Rational Use of Pancreatic Enzymes for Pancreatic Insufficiency and Pancreatic Pain

We describe the rational use of enteric coated and unprotected replacement pancreatic enzymes for treatment of malabsorption due to pancreatic insufficiency and for pancreatic pain. Enteric coated formulations mix poorly with food allowing separation of enzymes and nutrients when emptying from the stomach. The site of dissolution of the enteric coating in the intestine is also unpredictable and enzymes may not be released until the distal intestine. Together, these barriers result in the lack of dose-response such that the strategy of increasing the dosage following a suboptimal effect is often ineffective. The ability to maintain the intragastric pH ≥4 with the combination of proton pump inhibitors and antacids suggests that it should be possible to reliably obtain a good response with uncoated enzymes. We also discuss the recognition, treatment and prevention of nutritional deficiencies associated with pancreatic insufficiency and recommend a test and treat strategy to identify and resolve nutritional deficits. Finally, we focus on mechanisms causing pain that may be amenable to therapy with pancreatic enzymes. Pain due to malabsorbed digestive contents can be prevented by successful therapy of malabsorption. Feedback inhibition of endogenous pancreatic secretion can prevent pain associated with pancreatic secretion but requires use of non-enteric coated formulations.

In search of the grail: A race for acid suppression

Proton pump inhibitors are the reference standards for the treatment of acid-related diseases. Acid suppression in gastroesophageal reflux disease is associated with a high rate of mucosal cicatrization, but symptom response differs among endoscopic phenotypes. Extraesophageal manifestations have a good clinical response in patients that present with abnormal acid exposure (diagnostic test) in the esophagus. Proton pump inhibitors have shown their effectiveness for reducing symptom intensity in nighttime reflux and sleep disorders, improving quality of life and work productivity. That can sometimes be achieved through dose modifications by splitting or increasing the dose, or through galenic formulation. Proton pump inhibitors are not exempt from controversial aspects related to associated adverse events. Technological development is directed at improving proton pump inhibitor performance through increasing the half-life, maximum concentration, and area under the curve of the plasma concentrations through galenic formulation, as well as creating safer and more tolerable drugs. The present review is focused on the mechanisms of action, pharmacokinetic properties, and technological advances for increasing the pharmacologic performance of a proton pump inhibitor.

Interchangeable Use of Proton Pump Inhibitors Based on Relative Potency

Although proton pump inhibitors (PPIs) are widely used, their relative potency and ideal dosing regimens remain unclear. We analyzed data from randomized clinical trials that performed pH testing in patients receiving solid-dose PPI formulations (omeprazole, esomeprazole, lansoprazole, pantoprazole, rabeprazole) for a minimum of 5 days. We used omeprazole equivalency and the surrogate biomarker, percentage time pH > 4 over a 24-hour period (pH4time), to compare PPI effectiveness for different PPIs given once, twice, or 3 times daily. We found that increasing strength of once-daily PPIs (9-64 mg omeprazole equivalents) increased pH4time linearly from approximately 10.0 to 15.6 hours; higher doses produced no further increase in pH4time. Increasing the frequency to twice-daily PPI increased pH4time linearly, from approximately 15.8 to 21.0 hours. Three-times daily PPIs performed similarly to twice-daily PPIs. The costs of PPIs varied greatly, but the cost variation was not directly related to potency. We conclude that PPIs can be used interchangeably based on potency. Using twice-daily PPIs is more effective in increasing efficacy increasing once-daily PPI dosage. Omeprazole and lansoprazole (30 mg) and 20 mg of esomeprazole rabeprazole are functionally equivalent.

Discontinuing Long-Term PPI Therapy: Why, With Whom, and How?

Proton pump inhibitors (PPIs) are among the most widely used class of drugs prescribed over the long term in all of clinical medicine with 8-10% of ambulatory adults have been prescribed a PPI in the past 30 days. However, numerous studies have raised doubts about the long term safety of PPI use. The purpose of this review is threefold: (i) To provide an overview of the current evidence demonstrating associations between PPI use and adverse health outcomes and the likelihood of the associations being causal (Why?); (ii) To be able to identify long-term PPI users in whom the intensity of PPI therapy could be reduced or in whom PPIs could be eliminated outright (Who?); and (iii) To provide strategies on how to reduce or stop chronic PPI therapy while maintaining symptom control and reducing the risk for symptom or upper GI disease recurrence (How?).

25 Years of Proton Pump Inhibitors: A Comprehensive Review

Proton pump inhibitors (PPIs) were clinically introduced more than 25 years ago and have since proven to be invaluable, safe, and effective agents for the management of a variety of acid-related disorders. Although all members in this class act in a similar fashion, inhibiting active parietal cell acid secretion, there are slight differences among PPIs relating to their pharmacokinetic properties, metabolism, and Food and Drug Administration (FDA)-approved clinical indications. Nevertheless, each is effective in managing gastroesophageal reflux disease and uncomplicated or complicated peptic ulcer disease. Despite their overall efficacy, PPIs do have some limitations related to their short plasma half-lives and requirement for meal-associated dosing, which can lead to breakthrough symptoms in some individuals, especially at night. Longer-acting PPIs and technology to prolong conventional PPI activity have been developed to specifically address these limitations and may improve clinical outcomes.

Post-fundoplication symptoms and complications: Diagnostic approach and treatment

Laparoscopic Nissen fundoplication is currently considered the surgical treatment of choice for gastroesophageal reflux disease (GERD) and its long-term effectiveness is above 90%. Adequate patient selection and the experience of the surgeon are among the predictive factors of good clinical response. However, there can be new, persistent, and recurrent symptoms after the antireflux procedure in up to 30% of the cases. There are numerous causes, but in general, they are due to one or more anatomic abnormalities and esophageal and gastric function alterations. When there are persistent symptoms after the surgical procedure, the surgery should be described as "failed". In the case of a patient that initially manifests symptom control, but the symptoms then reappear, the term "dysfunction" could be used. When symptoms worsen, or when symptoms or clinical situations appear that did not exist before the surgery, this should be considered a "complication". Postoperative dysphagia and dyspeptic symptoms are very frequent and require an integrated approach to determine the best possible treatment. This review details the pathophysiologic aspects, diagnostic approach, and treatment of the symptoms and complications after fundoplication for the management of GERD.

Randomised clinical trial: efficacy and safety of vonoprazan vs. lansoprazole in patients with gastric or duodenal ulcers - results from two phase 3, non-inferiority randomised controlled trials

BACKGROUND

Vonoprazan is a new potassium-competitive acid blocker for treatment of acid-related diseases.

AIM

To conduct two randomised-controlled trials, to evaluate the non-inferiority of vonoprazan vs. lansoprazole, a proton pump inhibitor, for treatment of gastric ulcer (GU) or duodenal ulcer (DU).

METHODS

Patients aged ≥20 years with ≥1 endoscopically-confirmed GU or DU (≥5 mm white coating) were randomised 1:1 using double-dummy blinding to receive lansoprazole (30 mg) or vonoprazan (20 mg) for 8 (GU study) or 6 (DU study) weeks. The primary endpoint was the proportion of patients with endoscopically confirmed healed GU or DU.

RESULTS

For GU, 93.5% (216/231) of vonoprazan-treated patients and 93.8% (211/225) of lansoprazole-treated patients achieved healed GU; non-inferiority of vonoprazan to lansoprazole was confirmed [difference = -0.3% (95% CI -4.750, 4.208); P = 0.0011]. For DU, 95.5% (170/178) of vonoprazan-treated patients and 98.3% (177/180) of lansoprazole-treated patients achieved healed DU; non-inferiority to lansoprazole was not confirmed [difference = -2.8% (95% CI -6.400, 0.745); P = 0.0654]. The incidences of treatment-emergent adverse events were slightly lower for GU and slightly higher for DU with vonoprazan than with lansoprazole. There was one death (subarachnoid haemorrhage) in the vonoprazan group (DU). The possibility of a relationship between this unexpected patient death and the study drug could not be ruled out. In both studies, increases in serum gastrin levels were greater in vonoprazan-treated vs. lansoprazole-treated patients; levels returned to baseline after treatment in both groups.

CONCLUSIONS

Vonoprazan 20 mg has a similar tolerability profile to lansoprazole 30 mg and is non-inferior with respect to GU healing and has similar efficacy for DU healing.

Challenges of correlating pH change with relief of clinical symptoms in gastro esophageal reflux disease: a phase III, randomized study of Zegerid versus Losec

Background

Zegerid (on demand immediate-release omeprazole and sodium bicarbonate combination therapy) has demonstrated earlier absorption and more rapid pH change compared with Losec (standard enteric coated omeprazole), suggesting more rapid clinical relief of heartburn. This Phase III, multicenter, double-blind, double-dummy, randomized study assessed the clinical superiority of Zegerid versus Losec for rapid relief of heartburn associated with gastro-esophageal reflux disease (GERD).

Methods

Patients with a history of frequent (2 3 days/week) uncomplicated GERD, were randomized to receive Zegerid (20mg) or Losec (20mg) with corresponding placebo. Study medication was self-administered on the first episode of heartburn, and could be taken for up to 3 days within a 14 day study period. Heartburn severity was self assessed up to 180 minutes post dose (9 point Likert scale). Primary endpoint was median time to sustained response (≥3 point reduction in heartburn severity for ≥45 minutes).

Results

Of patients randomized to Zegerid (N=122) or Losec (N=117), 228/239 had recorded ≥1 evaluable heartburn episodes and were included in the modified intent-to-treat population. No significant between-group differences were observed for median time to sustained response (60.0 vs. 52.2 minutes, Zegerid [N=117] and Losec [N=111], respectively), sustained partial response (both, 37.5 minutes) and sustained total relief (both, 105 minutes). Significantly more patients treated with Zegerid reached sustained total relief within 0–30 minutes post dose in all analysis sets (p<0.05). Both treatments were well tolerated and did not raise any safety concerns.

Conclusions

Superiority of Zegerid over Losec for rapid heartburn relief was not demonstrated; both treatments were equally effective however the rapid onset of action of Losec was unexpected. Factors, including aspects of study design may have contributed to this. This study supports previously reported difficulty in correlating intra-gastric pH change with clinical effect in GERD therapy, highlighting the significance of several technical considerations for studies of this type.

Trial registration

ClinicalTrials.gov NCT01493089

Acid peptic diseases: pharmacological approach to treatment

Acid peptic disorders are the result of distinctive, but overlapping pathogenic mechanisms leading to either excessive acid secretion or diminished mucosal defense. They are common entities present in daily clinical practice that, owing to their chronicity, represent a significant cost to healthcare. Key elements in the success of controlling these entities have been the development of potent and safe drugs based on physiological targets. The histamine-2 receptor antagonists revolutionized the treatment of acid peptic disorders owing to their safety and efficacy profile. The proton-pump inhibitors (PPIs) represent a further therapeutic advance due to more potent inhibition of acid secretion. Ample data from clinical trials and observational experience have confirmed the utility of these agents in the treatment of acid peptic diseases, with differential efficacy and safety characteristics between and within drug classes. Paradigms in their speed and duration of action have underscored the need for new chemical entities that, from a single dose, would provide reliable duration of acid control, particularly at night. Moreover, PPIs reduce, but do not eliminate, the risk of ulcers in patients taking NSAIDs, reflecting untargeted physiopathologic pathways and a breach in the ability to sustain an intragastric pH of more than 4. This review provides an assessment of the current understanding of the physiology of acid production, a discussion of medications targeting gastric acid production and a review of efficacy in specific acid peptic diseases, as well as current challenges and future directions in the treatment of acid-mediated diseases.

Patient adherence to prescribed medication instructions for dyspepsia: the DIAMOND-study

BACKGROUND

Insight into patient adherence is needed to enable an effect evaluation of medication for dyspepsia.

OBJECTIVES

Adherence was explored by investigating two adherence outcome measures (completeness and intake fidelity) using data from the DIAMOND-study.

METHODS

The DIAMOND-study is a pragmatic RCT comparing a 'step-up' with a 'step-down' treatment strategy. In step 1 participants (n =653) were instructed to use five pills/day for maximally 30 days: an antacid 4dd plus a placebo 1dd ('step-up') or a proton pump inhibitor 1dd plus a placebo 4dd ('step-down'). If the complaints persisted, step 2 was started (H(2)-receptor antagonist 2dd), and subsequently step 3 (five pills/day, placebo and verum vice versa from step 1). Completeness was assessed by pill counts, intake fidelity by patient questionnaires measuring the degree to which patients adhered to specific instructions concerning timing, frequency, dose and way of intake.

RESULTS

In step 1, patients used on average 3.9 pills/day (78% of the prescribed doses), in step 2, 1.7 pills/day (85%) and in step 3, 3.6 pills/day (72%). For the four times daily pills, half of the patients used less than 80% of the prescribed pills per day. This was one third of the patients for the twice daily pills and one quarter for the once daily pills. There were no completeness differences between active or placebo medication and no differences between the study arms. As regards intake fidelity, 70% of the patients made one or more errors in the medication intake.

CONCLUSION

There is room for improvement in adherence rates for dyspepsia medication.

Historical impact to drive research in peptic ulcer disease

The story of gastric acid secretion began with early ideas on gastric secretion (Spallanzani and de Réaumur, 17th century) and with first descriptions of food digestion (Dupuytren and Bichat, Beaumont, early 18th century), followed by proof that gastric juice contained acid (Prout, early 18th century). The research continued with first descriptions of gastric glands as the source of gastric acid and its changes upon digestive stimulus (Purkinje and Golgi, mid and late 19th century). The theory of 'nervism' - the neuro-reflex stimulation of gastric secretion by vagal nerve (Pavlov, early 20th century) was contrasted by a histamine-mediated concept of gastric secretion (Popielski and Code, mid 20th century). Thus, gastric acid and pepsin (Schwann, early 19th century) were found to be essential for food digestion and studies also pointed to histamine, being the most potent final common chemostimulator of oxyntic cells. The discoveries in etiopathogenesis of mucosal injury were marked by the famous dictum: 'No acid, no ulcer' ('Ohne saueren Magensaft kein peptisches Geschwür', Schwarz, 1910) that later induced the term of 'mucosal defense' and the notion that the breaking of 'gastric mucosal barrier' represents the initial step in the process of mucosal injury (Davenport, Code and Scholer, mid 20th century). The prostaglandins were shown to influence all major components of gastric mucosal barrier, described with the term 'cytoprotection' (Vane, Robert and Jacobson, 1970s). Beginning in the latter half of 19th century, the studies on gastric bacteriology that followed enabled the discovery of association between Campylobacter (Helicobacter) pylori and peptic ulcers (Warren and Marshall, 1980s) that led to worldwide major interventions in treating peptic ulcer disease. The surgical approach to peptic ulcer had been outlined by resection procedures (Billroth, Pean, Moynihan, late 19 century) and vagotomy, with or without drainage procedures (Jaboulay, Latarjet, Dragstedt, mid 20th century). Antacids, protective agents, anticholinergics, and later gastrin antagonists and prostaglandins were used for decades in the treatment of peptic ulcer, with differing effects. The advent of the concept of H(2)-receptor antagonists (Black, 1970s) and the discovery of acid (proton) pumps in parietal cells (Ganser, Forte and Sachs, late 1970s) paved the way for potent (H(2) antagonists) and profound acid inhibition (proton pump inhibitors) that revolutionized the treatment of acid-related disorders, including peptic ulcer disease. Worldwide, peptic ulcer and its complications remain the cause of significant morbidity, especially in older age groups, representing a major burden for ambulatory and hospital healthcare resources.

Antiulcer effect of the methanolic extract of Tamarindus indica seeds in different experimental models

Background:

Peptic ulcer is a global health problem of the gastrointestinal tract characterized by mucosal damage secondary to pepsin and gastric acid secretion which occurs due to due to an imbalance between offensive and defensive factors.

Objective:

The present study was carried out with methanolic extract of the seed coat of Tamarindus indica Linn. to evaluate its antiulcer potential on ibuprofen, alcohol and pyloric ligation induced gastric lesions.

Materials and Methods:

Doses of 100 mg/kg & 200 mg/kg of methanolic extract wre administered orally to rats of different groups. Ranitidine at a dose of 50 mg/kg was used as a standard drug for these gastric ulcer models. The gastric content was collected and the volume was measured. The ulceration index was determined by examining the inner lining of each stomach. Furthermore, the effect was assessed by free acidity, pepsin activity, total carbohydrate (TC), protein content (PK).

Result:

The result showed that the methanolic extract of seed coats of Tamarindus indica significantly reduce the total volume of gastric juice, free and total acidity of gastric secretion (P < 0.01) in pylorus ligation induced ulcer model as is comparable with the standard drug ranitidine. There was also a significant reduction in ulcer index (P < 0.01) as compared to control group.

Conclusion:

The methanolic extracts of seed coat of Tamarindus indica can be used as a new source of antiulcer agent in animals.

The pharmacodynamics and pharmacokinetics of S-tenatoprazole-Na 30 mg, 60 mg and 90 mg vs. esomeprazole 40 mg in healthy male subjects

BACKGROUND

Racemic tenatoprazole 40 mg/day provides more prolonged acid suppression than esomeprazole 40 mg/day.

AIM

To compare pharmacodynamic and pharmacokinetic profiles of tenatoprazole and esomeprazole.

METHODS

A single-centre, double-blind, double-dummy, randomized, 4-way, cross-over study was conducted in 32 healthy male subjects. S-tenatoprazole-Na 30, 60 or 90 mg, or esomeprazole 40 mg was administered once daily for 5 days with 10-day washout intervals. The 24-h intragastric pH was recorded at baseline and on day 5 of each period.

RESULTS

On day 5, median pH (5.34 +/- 0.45 and 5.19 +/- 0.52 vs. 4.76 +/- 0.82, respectively, P < 0.002) and percentage time with pH > 4 (80 +/- 11 and 77 +/- 12, vs. 63 +/- 11 respectively, P < 0.0001) for 24-h were higher with S-tenatoprazole-Na 90 mg and 60 mg than esomeprazole. In nocturnal periods, S-tenatoprazole-Na 90 mg, 60 mg and 30 mg were superior to esomeprazole with regard to median pH (5.14 +/- 0.64, 4.94 +/- 0.65, 4.65 +/- 0.86 and 3.69 +/- 1.18 respectively, P < 0.0001) and percentage time with pH > 4 (77 +/- 12, 73 +/- 17, 64 +/- 17 and 46 +/- 17 respectively, P < 0.0001). Proportion of subjects with nocturnal acid breakthrough with S-tenatoprazole-Na 90 mg, 60 mg and 30 mg was significantly less than with esomeprazole (54.8, 43.3, 56.7 and 90.3 respectively, P < 0.04). The proportion of subjects with >16 hrs with pH >4 was significantly higher with S-tenatoprazole-Na 90 mg and 60 mg than with esomeprazole (87.1%, 83.3% and 41.9% respectively, P < 0.02).

CONCLUSIONS

S-tenatoprazole-Na produced significantly greater and more prolonged dose-dependent 24-h and nocturnal acid suppression than esomeprazole. S-tenatoprazole-Na may provide greater clinical efficacy compared with current PPIs for patients with ineffective once-daily therapy.

Gastric ulcer treatment: cure of Helicobacter pylori infection without subsequent acid-suppressive therapy: is it effective?

Whether it is a requirement to continue with anti-secretory therapy following anti-Helicobacter therapy in H. pylori positive gastric ulcers is an important question. As gastric ulcers tend to heal more slowly than duodenal ulcers, may be asymptomatic or only causing mild symptoms and success at curing H. pylori with current fist line therapies is 80% at best, clinicians will likely err on the side of caution and continue acid suppressive therapy to ensure healing of gastric ulcers. This is certainly recommended when dealing with bleeding ulcers.

Proton pump inhibitors: effective first-line treatment for management of dyspepsia

The aim of this study was to evaluate the reasons for trial exclusion among dyspeptic patients and estimate the proportion that may have benefited from proton pump inhibitor (PPI) therapy. Stringent inclusion criteria for enrollment in two multicenter functional dyspepsia trials included dyspepsia (predominant persistent/recurrent upper abdominal discomfort [UAD] during the prior 3 months) of at least moderate intensity during > or =30% of days during the prior 2 to 3 weeks. Exclusion criteria were mild/infrequent UAD; heartburn and UAD of equal frequency; predominant heartburn with UAD; endoscopic evidence of erosive esophagitis or Barrett's or gastric and/or duodenal erosions (>5) or ulcers; irritable bowel syndrome (IBS); other gastrointestinal diagnoses; or other "non-categorized" disorders. Of 2,588 screened patients, 1,667 were excluded. Excluded patients by category had mild/infrequent UAD (12.5%, n=324), heartburn and UAD of equal frequency (1.1%, n=29), predominant heartburn with UAD (11.6%, n=300), endoscopic evidence of erosive esophagitis or Barrett's (6.2%, n=160), gastric and/or duodenal erosions (1.4%, n=36), gastric and/or duodenal ulcers (2.0%, n=53), IBS (7%, n=180), "other" gastrointestinal diagnoses (2.8%, n=73), or other "non-categorized" disorders (19.8%, n=512). Fifty-four percent of patients (902/1,667) had symptoms/diagnoses that would be expected to improve with PPI therapy. Individuals with IBS, "other," or "non-categorized" disorders were considered to have symptoms unlikely to respond to PPI treatment. Empiric PPI treatment would be expected to provide symptom relief to the majority of dyspepsia sufferer who present in clinical practice. PPIs represent the best currently available therapy for acid-related disorders and should be considered the first-line management approach in patients with uninvestigated dyspepsia.

Effect on intragastric pH of a PPI with a prolonged plasma half-life: comparison between tenatoprazole and esomeprazole on the duration of acid suppression in healthy male volunteers

OBJECTIVE

To compare the inhibitory effect of a novel proton pump inhibitor (PPI), tenatoprazole 40 mg once daily, with esomeprazole 40 mg once daily on intragastric acidity.

METHODS

A randomized, investigator-blind, two-way, crossover study was conducted in 30 healthy Helicobacter pylori negative male volunteers. Tenatoprazole 40 mg or esomeprazole 40 mg was administered once daily for 7 consecutive days with a 4-wk washout period between treatments. Ambulatory 24-h intragastric pH was recorded at baseline, after 7 days' treatment, and 3 and 5 days after treatment was stopped.

RESULTS

At presumed steady-state (day 7), median 24-h pH values were 5.02 and 4.79 for tenatoprazole and esomeprazole, respectively. There was a significant difference between tenatoprazole and esomeprazole during the nocturnal period when mean pH was 4.64 +/- 0.67 versus 3.61 +/- 0.90, respectively (p < 0.0001), as well as a significantly higher mean percentage of time with pH >4 on tenatoprazole (72.5 +/- 14.9 vs 62.2 +/- 13.6, p < 0.0001). The effect of tenatoprazole was still present 5 days after treatment withdrawal especially during the night-time. The mean area under the plasma concentration-time curve and elimination half-time was significantly higher in the tenatoprazole group as compared with the esomeprazole group.

CONCLUSION

Tenatoprazole 40 mg daily provides a prolonged duration of acid suppression and a shorter nocturnal acid breakthrough in healthy volunteers, even after stopping the drug. Thus, tenatoprazole may provide greater clinical efficacy for patients in whom a once daily PPI is ineffective. Further studies are indicated.

Comparative study of the speed of acid-suppressing effects of oral administration of cimetidine and famotidine

BACKGROUND AND AIM

H2 histamine receptor antagonists (H2RAs) are widely used in patients with acid-related diseases, and the onset of antisecretory activity of H2RAs is reported to be faster than that of proton pump inhibitors (PPIs). The aim of this study was to compare the rapidity of onset of antisecretory activity of cimetidine and famotidine when orally administered.

METHODS

Fifteen healthy male Japanese volunteers (five H. pylori-positive and 10 H. pylori-negative) participated in a randomized cross-over study. All subjects were examined three times by ambulatory 6-h pH monitoring (from 17:30 to 23:30) with no medication or oral administration of 400 mg of cimetidine or 20 mg of famotidine. Drugs were administered at 19:30 after eating a standard meal, and plasma concentrations were also examined for 4 h periods.

RESULTS

The plasma concentration of cimetidine increased rapidly after oral administration, while that of famotidine increased gradually. Intragastric pH was increased and percentage time with pH < 4.0 decreased significantly 2 h after administration of either cimetidine or famotidine. There was no statistically significant difference in acid-suppressing effect between cimetidine and famotidine during the short-term post-administration period.

CONCLUSION

Rapidity of antisecretory activity did not differ between oral cimetidine and famotidine administered orally.

Acid-suppressive efficacy of a reduced dosage of rabeprazole: comparison of 10 mg twice daily rabeprazole with 20 mg twice daily rabeprazole, 30 mg twice daily lansoprazole, and 20 mg twice daily omeprazole by 24-hr intragastric pH-metry

Rabeprazole achieves more potent acid suppression than other proton pump inhibitors. Therefore it is administered at reduced as well as high dosages in eradication therapy for Helicobacter pylori; however, there is incomplete assessment of the efficacy of a reduced dosage of rabeprazole as might be employed in therapy. In this study, we evaluated acid-suppressive efficacy of a reduced dosage of rabeprazole on day 7 by 24-hr pH-metry in 10 healthy male cytochrome P-450 2C19 extensive metabolizers without Helicobacterpylori infection and compared the results with those of high dosages of rabeprazole, lansoprazole, and omeprazole. Median intragastric pH value, pH >3 holding time ratio (pH>3HT), pH>4HT, pH>5HT, pH>6HT, and pH>7HT for 24 hr with rabeprazole, 10 mg twice daily, were not significantly different from those of rabeprazole, 20 mg twice daily, lansoprazole, 30 mg twice daily, and omeprazole, 20 mg twice daily. In conclusion, for acid-suppressive efficacy, a reduced dosage of rabeprazole is comparable to high dosages of rabeprazole, lansoprazole, and omeprazole.

Systematic review and meta-analysis: is 1-week proton pump inhibitor-based triple therapy sufficient to heal peptic ulcer?

AIMS

To systematically review the efficacy on ulcer healing of 1-week combination of a proton pump inhibitor plus two antibiotics and to perform a meta-analysis of randomized clinical trials to evaluate whether 7 days of proton pump inhibitor-based triple therapy is sufficient to heal peptic ulcer.

METHODS

Studies where 1-week proton pump inhibitor-based triple therapy was administered to heal peptic ulcer were included. Randomized clinical trials comparing the efficacy on ulcer healing of 7-day proton pump inhibitor-based triple therapy versus this same regimen but prolonging the proton pump inhibitor for several more weeks were included in the meta-analysis. Electronic and manual bibliographical searches were conducted. Meta-analysis was performed combining the odds ratios of the individual studies.

RESULTS

Twenty-four studies (2342 patients) assessed ulcer healing with 1-week proton pump inhibitor-based triple therapy. Mean healing rate was 86%, and 95% in Helicobacter pylori-eradicated patients. Six studies (862 patients), were included in the meta-analysis. Mean ulcer healing rate with a 7-day treatment was 91% versus 92% when proton pump inhibitor was prolonged for 2-4 more weeks (odds ratio = 1.11; 95% confidence interval = 0.71-1.74).

CONCLUSION

In patients with peptic ulcer and H. pylori infection, prolonging therapy with proton pump inhibitor after a triple therapy for 7 days with a proton pump inhibitor and two antibiotics is not necessary to induce ulcer healing.

Review article: the pharmacodynamics and pharmacokinetics of proton pump inhibitors--overview and clinical implications

During the past two decades, enormous changes occurred in the management of gastric acid-related diseases. First, the histamine2-receptor antagonists were introduced, offering patients the first single-agent therapy that effectively reduced gastric acid secretion. Proton pump inhibitors became widely available in the early 1990s, and they generally appeared to be superior to the histamine2-receptor antagonists in acid-suppressing activity, symptom control and healing. Most physicians now use proton pump inhibitors as first-line treatment for many patients with acid-peptic disorders, including erosive gastro-oesophageal reflux disease (GERD), nonerosive reflux disease (NERD) and duodenal and gastric ulcers. Although proton pump inhibitors are often thought to be interchangeable, some differences have emerged in their pharmacological properties, which may be reflected in some aspects of clinical efficacy. Such differences include potency, speed of onset and duration of pH 'holding times'. Helicobacter pylori has now been recognized as an important factor in the pathogenesis of acid-peptic disorders. It is clear that H. pylori eradication can dramatically reduce the chronicity of gastric and duodenal ulcers, and accepted therapeutic regimens for H. pylori eradication now include proton pump inhibitors and two or more antibiotics. Although all accepted proton pump inhibitor-based 'triple therapies' are roughly equivalent in efficacy, there is now a shortened regimen available that will potentially enhance compliance and decrease cost. This review examines the relative advantages of proton pump inhibitors vs. histamine2-receptor antagonists in the context of acid suppression and in various gastric acid-related diseases. A brief overview presents the pharmacodynamics and pharmacokinetics of the proton pump inhibitors with particular attention paid to rabeprazole, one of the newer drugs in its class.

Review article: pH, healing and symptom relief with rabeprazole treatment in acid-related disorders

Control of gastric acid secretion by antisecretory agents has been the cornerstone of therapy in the successful management of all acid-related disorders, including gastro-oesophageal reflux disease (GERD), and duodenal and gastric ulcer. Treatment efficacy has been strongly correlated with degree and duration of acid suppression within the 24-h period and with total duration of therapy. All proton pump inhibitors are highly effective for the healing of ulcers and erosive oesophagitis. All have closely similar mechanisms of action, yet important pharmacological differences exist, which can significantly impact certain aspects of their clinical efficacy. Rabeprazole's rapid activation over a wide pH range may be the explanation for its early onset of effective acid inhibition compared with other proton pump inhibitors such as omeprazole, lansoprazole and pantoprazole. Like rabeprazole, esomeprazole is also a potent inhibitor of gastric acid at steady state, although it is thought that rabeprazole may provide enhanced first-day acid suppression compared with esomeprazole. First-day antisecretory efficacy should produce faster symptom relief, a hypothesis supported by clinical data. Moreover, drugs with pharmacological profiles that include both rapid onset and potent antisecretory effects should help control healthcare costs by reducing the need for otherwise commonly used twice-daily proton pump inhibitor administration.

Review article: trials on reflux disease -- the role of acid secretion and inhibition

The importance of gastric acid in the pathophysiology of gastro-oesophageal reflux disease is substantiated by the extraordinary therapeutic success of acid inhibition in the management of the disease. The influence of many risk factors for gastro-oesophageal reflux disease is also mediated through their effect on gastric acid secretion and acid reflux. Helicobacter pylori reduces the risk of gastro-oesophageal reflux disease by causing corpus gastritis and reducing gastric acid output. The geographical and temporal trends of H. pylori infection in human populations and its influence on gastric acid secretion are responsible for much of the apparent epidemiology of gastro-oesophageal reflux disease. On average, intra-oesophageal exposure to acid is higher in patients who respond poorly to antisecretory medication. It also tends to increase with increasing severity of reflux disease. However, gastric acid secretion and intra-oesophageal acid exposure vary markedly in reflux patients. The degrees of gastric or intra-oesophageal acidity do not allow the prediction of the presence or severity of gastro-oesophageal reflux disease in the individual subject. The many clinical trials on gastro-oesophageal reflux disease indicate that the reflux of gastric acid constitutes an essential mechanism in the development of this disease, but that additional and partly unknown risk factors must contribute to its aetiology and promote its occurrence in the individual patient.

Antiulcerogenic activity of ethanol extract of Solanum variabile (false "jurubeba")

The ethanol extract (EE) of the aerial parts of Solanum variabile Mart. (Solanaceae) was investigated for its ability to prevent ulceration of the gastric and duodenal mucosa at different doses. Its ability to heal chronic ulcer processes was also evaluated. When the HCl/ethanol solution was used to induce gastric ulcer, the EE produced a significant dose-dependent reduction of lesion formation of 51, 74 and 89%, at doses of 250, 500 and 1000 mg/kg, respectively. The 100 mg/kg dose had no significant activity. The EE also significantly reduced the gastric lesions induced by the combination of indomethacin and bethanechol (60 and 72%) at doses of 500 and 1000 mg/kg and also reduced stress-induced gastric ulcer (41%) but only at the doses of 1000 mg/g (P < 0.05). The pylorus-ligature experiment demonstrated that the highest EE dose affected significantly the gastric juice parameters by increasing pH values from 4.08 (negative control) to 5.42 and decreasing acid output from 7.16 (negative control) to 4.26 mEq.mL, 4h. A decrease of gastric contents from 370 mg (negative control) to 240 mg was also observed. The results obtained in the chronic gastric ulcer model indicated that a single oral dose of Solanum variabile (1000 mg/kg) administered for 14 consecutive days accelerated the ulcer healing by 46% compared to a 55% effect of cimetidine. Also, at the dose of 1000 mg/kg, the EE inhibited the onset of duodenal lesions by 64%. The data suggest that the EE of Solanum variabile has a significant preventive, curative and duodenal anti-ulcer effect.

Treatment of acid-related diseases in the elderly with emphasis on the use of proton pump inhibitors

Proton pump inhibitors (PPIs) have revolutionised the treatment of acid-related disorders, and they have also made it possible to define the spectrum of acid inhibition required for optimal treatment in each disorder. Five PPIs are now available: the older drugs, omeprazole, lansoprazole and pantoprazole, and the two newest, rabeprazole and esomeprazole. These agents have predominantly been developed in the younger adult population, and data for the elderly population are limited. Subtle differences have emerged between the old and the new PPIs in their pharmacokinetic, pharmacodynamic and efficacy profiles. The degree of clinical relevance of these differences in the adult population is in question. However, according to this review, based on the available data for the elderly and by inference from the adult population, the differences are highly relevant in the elderly population. Studies of the pharmacokinetics of older PPIs demonstrated considerable variation in drug clearance that was reflected in a wide range of efficacy related to acid suppression with standard dosages. The newer PPIs offer several advantages over older agents, particularly in terms of rapid, profound and consistent acid inhibition. Consistent acid inhibition is particularly important in the elderly since clinical response is often difficult to judge in this patient group. An individual's cytochrome P450 (CYP) 2C19 genotype predicts the degree of acid suppression and consequently the clinical efficacy of the PPIs. The older PPIs are predominantly metabolised by CYP2C19, with this being of more importance for omeprazole and lansoprazole than pantoprazole. The hepatic metabolism of rabeprazole is predominantly by nonenzymatic reactions and minimally by CYP-mediated reactions, which therefore confers an advantage over older PPIs in that genetic polymorphisms for CYP2C19 do not significantly influence rabeprazole clearance, clinical efficacy or potential for drug interactions. The metabolism of esomeprazole involves CYP2C19 but to a lesser extent than its predecessor omeprazole. Furthermore, esomeprazole has a more rapid onset of action and less variation in clearance rates than omeprazole. Drug clearance decreases with age independently of CYP2C19 status, exaggerating some of the differences between the PPIs and increasing the risk of drug interactions.

Effects of tea from Turnera ulmifolia L. on mouse gastric mucosa support the Turneraceae as a new source of antiulcerogenic drugs

Turnera ulmifolia is a plant belonging to the family Turneraceae, popularly known in Brazil as chanana. This species is distributed from Guyana to southern Brazil where it is considered a weed. The plant occurs in tropical rain forest, fields, and gardens. Chanana tea is used in Brazilian folk medicine for the treatment of diseases related mainly to gastric dysfunction including gastric and duodenal ulcers. In this study, the ability of a lyophilized infusion, as an aqueous fraction (AqF) of the aerial parts of T. ulmifolia, was investigated for its ability to prevent ulceration of the gastric and duodenal mucosa was examined in mice and rats, respectively. The AqF significantly reduced the formation of lesions associated with HCl/ethanol administration by 39% and 46%, respectively, at doses of 500 mg/kg and 1000 mg/kg, p.o. The AqF also significantly reduced the incidence of gastric lesions induced by a combination of indomethacin and bethanechol by 58% and 72% at doses of 500 mg/kg and 1000 mg/kg, respectively. In stress-induced gastric ulcer, the inhibition by the AqF was 48%, 57%, and 58% at doses of 250 mg/kg, 500 mg/kg, and 1000 mg/kg, respectively (p<0.05). A pyloric ligature experiment showed that the highest dose of the AqF significantly affected the gastric juice parameters by increasing the pH from 2.5 (control) to 5.3 and decreasing the acid output from 11.3 (control) to 3.7 mEq/ml/4 h. The AqF had no significant effect on duodenal ulcers induced by cysteamine. Preliminary phytochemical screening confirmed that flavonoids were the major constituents of the AqF of T. ulmifolia. These results indicate that this extract has a significant antiulcerogenic effect, as popularly believed.

A meta-analysis comparing eradication, healing and relapse rates in patients with Helicobacter pylori-associated gastric or duodenal ulcer

AIM

To compare the effectiveness of Helicobacter pylori eradication in curing peptic ulcer disease in trials involving both gastric ulcer and duodenal ulcer.

METHODS

Twenty-four relevant randomized controlled trials and randomized comparative trials met the predefined selection criteria. Only proton pump inhibitor-based eradication trials were considered for the evaluation of eradication efficacy and ulcer healing. For the determination of relapse rates, all trials independent of the eradication therapy regimen were considered.

RESULTS

Data from 2102 patients were analysed comparing gastric ulcer with duodenal ulcer. No statistical differences between gastric ulcer and duodenal ulcer patients were found with regard to eradication rates (summarized odds ratio, 1.23; 95% confidence interval, 0.98-1.55) or ulcer relapse rates, whether in successfully H. pylori eradicated patients (summarized odds ratio, 0.69; 95% confidence interval, 0.26-1.84) or unsuccessfully H. pylori eradicated patients (summarized odds ratio, 1.48; 95% confidence interval, 0.85-2.56). Owing to heterogeneity, healing rates were not comparable.

CONCLUSIONS

The eradication of H. pylori infection cures both gastric and duodenal ulcer, and the cure rates are similar. This suggests that H. pylori is the key factor in peptic ulcer disease independent of the ulcer site.

Control of intragastric acidity with over-the-counter doses of ranitidine or famotidine

BACKGROUND

Histamine H2-receptor antagonists are available over the counter for the treatment of heartburn.

AIM

To compare the effects of low doses of ranitidine and famotidine on intragastric acidity in a three-way crossover study.

METHODS

Healthy subjects (12 male, 12 female) were dosed on three occasions with single oral doses of placebo, ranitidine, 75 mg, and famotidine, 10 mg, 1 h after lunch. The pH of gastric aspirates was then measured for 20 h. Subjects ate standard meals and snacks. Analysis of variance was used to determine the statistical significance of differences in acidity (mmol/L) during the day (12.30-22.30 hours) and night (22.30-08.30 hours).

RESULTS

Ranitidine and famotidine were superior (P < 0.05) to placebo in decreasing acidity for daytime and night-time intervals. There were no significant differences in mean gastric acidity between ranitidine and famotidine during the daytime (11.37 mmol/L vs. 13.42 mmol/L, respectively) and night-time (23.57 mmol/L vs. 24.74 mmol/L, respectively). Intragastric acidity after ranitidine was significantly lower than that after famotidine in the first 2.5-h period following dosing (4.32 mmol/L vs. 9.28 mmol/L; P < 0.05).

CONCLUSIONS

Lunchtime doses of ranitidine and famotidine decreased acidity during day- and night-time periods. The effect of ranitidine was significantly greater for the first 2.5 h after dosing.

Decreasing oesophageal acid exposure in patients with GERD: a comparison of rabeprazole and omeprazole

BACKGROUND

Rabeprazole has been shown to be more potent and faster than other proton pump inhibitors in in vitro studies and highly effective in decreasing oesophageal acid exposure in patients with gastro-oesophageal reflux disease (GERD).

AIM

This study was a multicentre, double-blind, placebo-controlled, randomized, parallel-group comparison of three active treatment regimens utilizing two different proton pump inhibitors, or placebo, administered over 7 days in patients with GERD.

METHODS

Eighty-two patients with symptomatic GERD were given placebo, rabeprazole 10 mg b.d., rabeprazole 20 mg o.m., or omeprazole 20 mg o.m. for 7 days. Twenty-four hour oesophageal pH monitoring was performed at baseline and repeated at the conclusion of the treatment period.

RESULTS

At the end of study, the percentage time (mean +/- s.d.) with pH < 4 over a 24-h period was significantly decreased by the three active regimens but without significant difference between them (9.27 +/- 4.77; 2.53 +/- 4.27; 2.02 +/- 1.71 and 2.91 +/- 4.06 for placebo, rabeprazole 10 mg b.d., rabeprazole 20 mg o.m. and omeprazole 20 mg o.m., respectively). Acid exposure was normalized in 90% of patients treated with rabeprazole 10 mg b.d., 95% treated with rabeprazole 20 mg o.m., 78% treated with omeprazole 20 mg o.m., and only 9.5% of patients treated with placebo. Both rabeprazole and omeprazole were well-tolerated.

CONCLUSIONS

Although rabeprazole 20 mg o.m. showed greater activity numerically, this study demonstrates that rabeprazole 10 mg b.d. and 20 mg o.m. are equivalent to omeprazole 20 mg o.m. in decreasing oesophageal acid exposure.

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.

A flowcytometric method for evaluation of acid secretion from isolated rat gastric mucosal cells

Studies on the gastric proton pump are mostly performed on the H(+), K(+)-ATPase enzyme in the microsomal preparation or by aminopyrine accumulation in the gastric parietal cells. H(+), K(+)-ATPase activity is estimated by both spectrophotometric and fluorimetric methods. In the present study, quenching or augmentation in acridine orange (AO) fluorescence was monitored on a flowcytometer in rat gastric mucosal cells. Rat gastric mucosal cells were isolated by the standard pronase--EDTA method. The effect of oleic acid, a proton pump inhibitory was evaluated on gastric parietal cell activity and was compared with its effect on proton transport, H(+), K(+)-ATPase, and p-nitrophenyl phosphatase (p-NPPase) activity in gastric microsomes. In addition, the effect of histamine and carbachol, gastric acid release inducers, was also investigated by flowcytometry in isolated parietal cells. Histamine and carbachol, in a dose-dependent manner, stimulated acid release from isolated gastric cells. Oleic acid also dose-dependently inhibited the basal and stimulated acid release from the cells, as well as in all three enzyme preparations associated with gastric proton pump activity. Thus, the results suggest that flowcytometric method might be used to study basal, as well as stimulated, proton pump activity in isolated gastric parietal cells.

Review article: the control of gastric acid and Helicobacter pylori eradication

This review focuses on the gastric acid pump as a therapeutic target for the control of acid secretion in peptic ulcer and gastro-oesophageal reflux disease. The mechanism of the proton pump inhibitors is discussed as well as their clinical use. The biology of Helicobacter pylori as a gastric denizen is then discussed, with special regard to its mechanisms of acid resistance. Here the properties of the products of the urease gene clusters, ureA, B and ureI, E, F, G and H are explored in order to explain the unique location of this pathogen. The dominant requirement for acid resistance is the presence of a proton gated urea transporter, UreI, which increases access of gastric juice urea to the intrabacterial urease 300-fold. This enables rapid and continuous buffering of the bacterial periplasm to approximately pH 6.0, allowing acid resistance and growth at acidic pH in the presence of 1 mM urea. A hypothesis for the basis of combination therapy for eradication is also presented.

CYP2C19 genotype status and intragastric pH during dosing with lansoprazole or rabeprazole

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.

Selection of patients for successful maintenance treatment of esophagitis with low-dose omeprazole: use of 24-hour gastric pH monitoring

OBJECTIVE

Treating patients with erosive esophagitis and maintaining remission in a cost-effective fashion is a desirable goal in clinical practice. There are no established criteria to identify patients with healed esophagitis who will subsequently remain in remission with low-dose omeprazole therapy. We investigated whether 24-h esophageal-gastric pH monitoring could provide criteria to select patients for low-dose omeprazole maintenance therapy.

METHODS

Seventy consecutive symptomatic outpatients with grade 2-3 reflux esophagitis were prospectively investigated. They were treated with 20 mg/day omeprazole for 2 months. Those with healed esophagitis were given alternate-evening 20-mg omeprazole maintenance therapy for 6 months. Clinical evaluation, endoscopy, and 24-h esophageal-gastric pH were done at the end of each treatment period. Results of pH studies of patients in remission were compared with those with endoscopically documented relapse of esophagitis.

RESULTS

In 63/70 patient (intention-to-treat, 90%; 95% confidence interval [CI], 83-97%) esophagitis was healed at 2 months. During the 6-month maintenance period esophagitis remain healed in 28 (G1) (40%; 95% CI, 29-52%), but recurred in 32 patients (G2). During healing with omeprazole 20 mg/day the 24-h gastric pH was below 4 for <10% of the time in 96% of the patients, who subsequently remained in long-term remission with low-dose maintenance therapy (G1), but not in any patient with recurrence of esophagitis (G2). The 10% threshold value has a specificity of 1.00 and sensitivity of 0.96.

CONCLUSIONS

The 24-h intragastric pH monitoring during 20 mg/day omeprazole therapy provides criteria by which to preselect patients with reflux esophagitis who will remain in remission with low-dose omeprazole therapy.

Review article: the pharmacology of rabeprazole

Rabeprazole sodium is a new substituted benzimidazole proton pump inhibitor with several differences compared with existing proton pump inhibitors. In vitro and animal studies have demonstrated that rabeprazole is a more potent inhibitor of H+,K(+)-ATPase and acid secretion than omeprazole, and is a more rapid inhibitor of proton pumps than omeprazole, lansoprazole, or pantoprazole. This probably reflects rabeprazole's faster activation in the parietal cell canaliculus. In human studies, once-daily doses of 5-40 mg of rabeprazole inhibit gastric acid secretion in a dose-dependent fashion. A once-daily dose of 20 mg has consistently achieved profound decreases in 24-h intragastric acidity in single and repeat dosing studies, in healthy volunteers and patients with either peptic ulcer disease or gastro-oesophageal reflux disease. Significantly greater decreases in intragastric acidity are achieved on day 1 of dosing with rabeprazole 20 mg than with omeprazole 20 mg. As with other proton pump inhibitors, rabeprazole has in vitro antibacterial activity against Helicobacter pylori, with greater activity against this organism than either lansoprazole or omeprazole. In addition to inhibiting bacterial urease activity, rabeprazole binds to several molecules on H. pylori. Clinical trials are needed to assess the clinical importance of these findings, as well as to assess whether the potential advantages of rabeprazole result in clinical benefit for patients with acid-related diseases.