Omeprazole: Helicobacter pylori makes thee greater yet

Eradication of Helicobacter pylori increases nocturnal intragastric acidity during dosing with rabeprazole, omeprazole, lansoprazole and placebo

BACKGROUND

The eradication of Helicobacter pylori decreases the antisecretory activity of omeprazole and lansoprazole. Rabeprazole is a potent proton pump inhibitor that may not be affected as greatly by H. pylori status.

AIM

To compare the effect of H. pylori eradication on intragastric acidity and plasma gastrin during dosing with lansoprazole, omeprazole, rabeprazole and placebo.

METHODS

Twenty-four healthy H. pylori-infected volunteers were studied on day 7 of dosing with placebo, lansoprazole 30 mg, omeprazole 20 mg and rabeprazole 20 mg, before and at least 5 weeks after H. pylori eradication. On each occasion, the 24-h intragastric acidity was measured by gastric aspiration. Plasma gastrin concentrations were measured hourly from 08.00 to 13.00 h.

RESULTS

Sixteen subjects completed the study. For all three drugs and placebo, H. pylori eradication increased intragastric acidity, particularly nocturnal acidity, and decreased plasma gastrin. There were no differences between the three drugs with respect to 24-h acidity, percentage of time pH > 4 or 5-h plasma gastrin, either before or after H. pylori eradication. Before eradication, the percentage nocturnal time at pH > 3 was significantly greater during rabeprazole than during lanso-prazole dosing.

CONCLUSIONS

The increase in intragastric acidity seen after H. pylori eradication during dosing with proton pump inhibitors is a drug-class effect, particularly affecting nocturnal acid control. This is related to increased spontaneous intragastric acidity after H. pylori eradication.

Cyclooxygenase 2-implications on maintenance of gastric mucosal integrity and ulcer healing: controversial issues and perspectives

Cyclooxygenase (COX), the key enzyme for synthesis of prostaglandins, exists in two isoforms (COX-1 and COX-2). COX-1 is constitutively expressed in the gastrointestinal tract in large quantities and has been suggested to maintain mucosal integrity through continuous generation of prostaglandins. COX-2 is induced predominantly during inflammation. On this premise selective COX-2 inhibitors not affecting COX-1 in the gastrointestinal tract mucosa have been developed as gastrointestinal sparing anti-inflammatory drugs. They appear to be well tolerated by experimental animals and humans following acute and chronic (three or more months) administration. However, there is increasing evidence that COX-2 has a greater physiological role than merely mediating pain and inflammation. Thus gastric and intestinal lesions do not develop when COX-1 is inhibited but only when the activity of both COX-1 and COX-2 is suppressed. Selective COX-2 inhibitors delay the healing of experimental gastric ulcers to the same extent as non-COX-2 specific non-steroidal anti-inflammatory drugs (NSAIDs). Moreover, when given chronically to experimental animals, they can activate experimental colitis and cause intestinal perforation. The direct involvement of COX-2 in ulcer healing has been supported by observations that expression of COX-2 mRNA and protein is upregulated at the ulcer margin in a temporal and spatial relation to enhanced epithelial cell proliferation and increased expression of growth factors. Moreover, there is increasing evidence that upregulation of COX-2 mRNA and protein occurs during exposure of the gastric mucosa to noxious agents or to ischaemia-reperfusion. These observations support the concept that COX-2 represents (in addition to COX-1) a further line of defence for the gastrointestinal mucosa necessary for maintenance of mucosal integrity and ulcer healing.

Treatment of Helicobacter pylori: an overview

Helicobacter pylori is recognized to be a serious pathogen, but there is still controversy as to who should be treated. There is consensus for treatment of Helicobacter-positive peptic ulcer and B-cell lymphoma. Lymphocytic gastritis and giant-fold gastritis (Ménétrièr's disease) may also respond to treatment. Patients with func-tional dyspepsia have a 20% placebo response with a 5-10% 'eradication' response, results not dissimilar from empirical treatment with a proton pump inhibitor. A 'test and treat' policy for patients with uninvesti-gated dyspepsia remains controversial. Some have suggested that eradication may increase the risk of GERD, or predispose to adenocarcinoma at the gastro-oesophageal junction. However, PPI treatment without Helicobacter eradication induces greater inflammation in the gastric corpus, the phenotype associated with non-cardia gastric cancer. A minority believe that Helicobacter should be eradicated in all individuals. When choosing treatment it is logical to start with a combination of antibiotics that, in the event of failure, will allow a second combination to be used without overlap.

Review article: is Helicobacter pylori status relevant in the management of GORD?

There is growing interest in the relationship between H. pylori infection and gastro-oesophageal reflux disease (GORD). However, this relationship is complex, as yet not fully elucidated, and probably based on a multiplicity of factors. The prevalence of H. pylori infection in patients with GORD is similar, more often lower than in matched controls. There is a negative correlation between H. pylori infection and the severity of GORD. There are many hypothetical mechanisms by which H. pylori infection may protect from the development of GORD. Conversely, there are many possible mechanisms by which H. pylori infection could theoretically foster the GORD. Patients after H. pylori eradication may develop GORD, and this seems to suggest a protective role of H. pylori infection, but other possible explanations include weight gain after H. pylori eradication, changes in dietary habits and smoking, and pre-existing GORD. H. pylori infected patients treated by various acid-inhibiting therapies such as proton pump inhibitors (PPIs), H2-receptors antagonists (H2-RA) or vagotomy, have an increase of their corpus gastritis severity, both in the activity of inflammation and in the density of organisms. Long-term therapy of GORD in H. pylori infected may lead to rapid progression of atrophic gastritis intestinal metaplasia and dysplasia, and increase the risk of developing gastric cancer. More recently it has been shown that H. pylori infection may interfere with the acid suppressive therapies used for treating GORD. In our opinion the progression of gastritis depends on the threshold of acid output at which H. pylori can 'flourish'. Recently interest is growing on gastric transitional zones and Helicobacter ecology. Any decrease of acid secretion changes the behaviour of H. pylori: the activity of gastritis improves in the antrum, but it deteriorates in the body. During proton pump inhibitor treatment, H. pylori redistribution occurs within the stomach, from an antral to a corpus or fundus prevalent pattern; corpus-fundus gastritis, exacerbated by PPI therapy, may result both in a diminished acid secretion and gastro-oesophageal reflux. The interest in Barrett's oesophagus is growing due to the associated risk of adenocarcinoma. The literature seems to demonstrate that the prevalence of H. pylori infection of the stomach in Barrett's oesophagus patients is not different from that exhibited by controls, roughly one-third of the subjects. Intestinal metaplasia of the gastric cardia seems to be equally frequent in patients with and without GORD. Finally, it appears unlikely that a causal relationship exists between H. pylori infection and Barrett's-associated adenocarcinoma.

Review article: the clinical influence of Helicobacter pylori in effective acid suppression-implications for the treatment of gastro-oesophageal reflux disease

The relationship between gastro-oesophageal reflux disease (GERD) and Helicobacter pylori is unclear. Recent data indicate that H. pylori probably exerts a protective effect against GERD. In recent years, the interaction between H. pylori, proton pump inhibitors and GERD has been widely studied. Currently available proton pump inhibitors produce significantly higher intragastric pH in H. pylori-positive patients than in those who are H. pylori negative, and this phenomenon may be clinically relevant. The mechanisms responsible for this difference in efficacy are not fully understood, although there are two major theories. Ammonia, produced by H. pylori, is able to neutralize gastric acid, and thus apparently increase the effect of acid suppressive agents (the 'ammonia theory'). The other theory is that decrease in acid output is due to the development of corpus gastritis during treatment with a proton pump inhibitor (the 'gastritis theory'). Treatment strategies to overcome this lowered sensitivity to acid suppression are to increase the frequency/dose of a proton pump inhibitor or to add an H2-receptor antagonist in the evening-but both have pharmaco-economic implications. An agent that could provide adequate pH control regardless of H. pylori status would be highly beneficial in the treatment of GERD, and may also lower treatment costs.

Consequences of Helicobacter pylori cure in ulcer patients

In the complex pathogenesis of genuine ulcer disease Helicobacter pylori (H. pylori) is an essential, although not on its own sufficient, causal factor. Eradication of the infection heals the active ulcer and, in the long term, leads to a drastic reduction in ulcer recurrence and attendant complications. Some patients remain symptomatic even without ulcer recurrence, and in these, pre-existing, exacerbated or induced gastro-oesophageal reflux disease is probably of some significance. Possible causes of ulcer relapse are reinfection, the use of ulcerogenic drugs and persistent gastric hypersecretion. In adults, and probably also in children from the age of six years, H. pylori reinfection is rare, provided that a sensitive and specific test for H. pylori is carried out at the earliest 4 weeks after concluding anti-bacterial treatment. The most common cause of the reappearance of H. pylori is recrudescence - true reinfection hardly ever occurs. The healing of H. pylori-associated ulcer disease improves the patient's quality of life and possibly also life expectancy. Computer-aided calculations, together with a randomized controlled study, have shown not only that individual patients benefit, but that also the health system profits financially. The hypothetical negative effects of H. pylori eradication treatment are still being controversially discussed.