A comparison of two different doses of omeprazole versus ranitidine in treatment of duodenal ulcers

[The second generation of gastric antisecretory agents: omeprazole]

Omeprazole is the first representative of a new class of gastric acid secretion inhibitors. It acts by specific and prolonged inhibition of H+K+ ATPase, or proton pump, which is the terminal and compulsory stage of acid secretion by the parietal cells. The drug therefore inhibits both basal and stimulated secretion. It appears from therapeutic trials that omeprazole administered in doses of 20 mg a.m. once a day is superior to the H2-receptor antagonists in the healing of active duodenal ulcers and ulcerated reflux oesophagitis. It is as active or slightly more active than histamine inhibitors in gastric ulcers. Finally, it is the treatment of choice to prevent ulcerations in Zollinger-Ellison syndrome. These are the 4 indications for omeprazole at the moment. The use of that drug for periods of a few weeks has not given rise to any significant side-effect.

Specific labelling of gastric H+,K+-ATPase by omeprazole

Acid secretion is conducted by the parietal cell of the gastric mucosa. The H+,K+-ATPase has been shown to be specifically located to this cell and during recent years been recognized as the gastric proton pump. Omeprazole, a known inhibitor of acid secretion, administered in vivo was found to bind specifically to the H+,K+-ATPase of the rabbit gastric mucosa. A stoichiometry of 2.1 mol radiolabel per mol phosphoenzyme was calculated at total inhibition of the H+,K+-ATPase enzyme activity. In isolated gastric glands prepared from omeprazole-treated animals, the secretagogue-induced increase in oxygen consumption, related to acid secretion, was inhibited to the same level as the H+,K+-ATPase activity. Both the degree of acid secretion inhibition induced by omeprazole and the amount of inhibitor bound to the H+,K+-ATPase were found to be dependent on the stimulation state of the parietal cell. Inhibition of secretion by the H2-receptor blocker ranitidine prior to omeprazole treatment prevented both the inhibition of H+,K+-ATPase and oxygen consumption normally observed with omeprazole and, furthermore, reduced the binding levels of radiolabel to the enzyme. Inhibition of acid secretion by the H+,K+-ATPase inhibitor SCH 28080 totally prevented the binding of radiolabel to the H+,K+-ATPase. The inhibition by omeprazole could be fully reversed in gastric glands and H+,K+-ATPase isolated from omeprazole-treated animals by addition of beta-mercaptoethanol. The major product formed during reactivation was the reduced form of omeprazole, compound H 168/22. Neutralization of the gastric glands in vitro with imidazole totally prevented the inhibitory action of omeprazole. These experiments demonstrate the necessity of acid for the inhibition of gastric acid secretion by omeprazole and the binding of the inhibitor to the H+,K+-ATPase, both in vivo and in vitro, and also the specificity of omeprazole for the H+,K+-ATPase.

Does maintenance therapy keep duodenal ulcers healed?

34 patients were endoscopically reexamined once a month while receiving ranitidine 150 mg at night to sustain remission of a duodenal ulcer. The cumulative recurrence rate after 1 year of maintenance treatment was 48%. 71% of recurrences were painless when first detected. The monthly percentage probabilities for asymptomatic ulcers rehealing, remaining unchanged, and causing pain were 33%, 63%, and 4%, respectively. Because painless ulcers may reheal, the number of ulcer recurrences detected during maintenance trials depends on the frequency of endoscopic reexamination of symptomless patients. Endoscopic examination of symptomless patients every 6 months would have failed to detect nearly half of all recurrences in this study. Thus an accurate assessment of the true incidence of asymptomatic (and, therefore, total) recurrences requires frequent endoscopic re-examination of symptomless patients. The clinical value of maintenance treatment should be judged by prevention of symptoms and complications, since it is not possible--either practically or mathematically--to determine the true incidence of ulcer recurrence, and because asymptomatic recurrences are irrelevant, provided maintenance treatment is continued.

Omeprazole or ranitidine in the treatment of reflux esophagitis. Results of a double-blind, randomized, Scandinavian multicenter study

One hundred and fifty-two patients with endoscopically verified erosive and/or ulcerative esophagitis entered a double-blind, randomized study comparing 20 mg omeprazole given once daily and ranitidine 150 mg twice daily. The efficacy and safety of 4 to 8 weeks' treatment were studied. Macroscopic healing of esophagitis was defined as complete epithelialization of all esophageal erosive and/or ulcerative lesions. One hundred and forty-four patients completed the first 4 weeks of treatment in accordance with the protocol. The healing rate was 67% in the omeprazole group and 31% in the ranitidine group (p less than 0.0001). The corresponding figures after 8 weeks' treatment were 85% and 50%, respectively (p less than 0.0001). The higher healing rate for omeprazole was also accompanied by a significantly faster and more substantial improvement in reflux symptoms. In the patient's own overall evaluation of symptoms, these had resolved in 51% of the omeprazole-treated patients already at the end of the 1st week of treatment, compared with 27% of those given ranitidine (p = 0.009). Both omeprazole and ranitidine were well tolerated, and there were no adverse events or clinically significant changes in the laboratory values attributable to the trial medication.

Omeprazole and ranitidine in treatment of reflux oesophagitis: double blind comparative trial

One hundred and sixty two patients with endoscopically proved reflux oesophagitis stratified for severity, 66 with grade 1 disease (erythema and friability) and 96 with grade 2 or 3 disease (including erosions or ulcerations), were allocated at random to double blind treatment with omeprazole 40 mg in the morning or ranitidine 150 mg twice daily for up to 12 weeks. A patient could be evaluated sooner if symptomatic relief and endoscopically normal mucosa (grade 0) were noted after four to eight weeks' treatment. Patients treated with omeprazole responded significantly more rapidly than those treated with ranitidine (p less than 0.0001), cumulative healing rates at four, eight, and 12 weeks being 90%, 100%, and 100% respectively for those with grade 1 disease and 70%, 85%, and 91% respectively for those with grade 2 or 3 disease in the omeprazole group. Corresponding rates in the ranitidine group were 55%, 79%, and 88% (grade 1) and 26%, 44%, and 54% (grade 2 or 3). Relief of the major symptoms of heartburn, regurgitation, and dysphagia and improvements in the histological appearance of the mucosa occurred earlier and were again more pronounced during treatment with omeprazole than with ranitidine. This observed superiority of omeprazole 40 mg in the morning over ranitidine 150 mg twice daily in the short term treatment of reflux oesophagitis was obtained without major clinical or biochemical side effects, but further research is needed into longer term use of omeprazole and the effects of the acid inhibition it induces.

Does the choice of acute treatment influence future ulcer relapse?

Despite the fact that the direct effect of drugs used for healing of ulcers does not last longer than hours, or at most a few days, some clinical studies have indicated that the rate of new ulcers after short courses of treatment depends on the drug used for healing. Several studies have now shown that the development of new ulcers in the same, regardless whether active ulcers have been healed with antacids or histamine H2-receptor antagonists. This lack of difference in clinical outcome is very likely true also for sucralfate and omeprazole in comparison with histamine H2-antagonists. A bismuth compound can perhaps prolong the period of clinical remission in a subgroup of patients in whom campylobacter pylori do not recur after finalized ulcer healing treatment. Other factors, i.e. smoking, and not the choice of ulcer healing drug, are of importance to recurrencies of new ulcers.

Double-blind multicentre comparison of omeprazole and ranitidine in the treatment of reflux oesophagitis

Omeprazole 60 mg once daily was compared with ranitidine 150 mg twice daily in an endoscopically-controlled, double-blind randomised trial in 51 outpatients with erosive or ulcerative reflux oesophagitis (grade 2 or 3). Endoscopy was repeated after 4 weeks and, in the absence of healing, again after 8 weeks. Symptoms were assessed before entry and after 2, 4, and 8 weeks. Patients who were unhealed after 8 weeks were blindly switched to the other drug and treatment was continued for another 4 to 8 weeks. The healing rate (change to grade 0 or 1 oesophagitis) after 4 weeks was 19 of 25 patients treated with omeprazole and 7 of 26 patients treated with ranitidine (p = 0.002). The corresponding figures after 8 weeks were 22 of 25 and 10 of 26 (p = 0.001). The higher healing rate with omeprazole was reflected in a significantly faster and stronger improvement of reflux symptoms. 13 patients, who were unhealed after 8 weeks on ranitidine, were healed after switching treatment. Healing was achieved in 1 of 3 patients who were switched to ranitidine. There were no adverse events or changes in laboratory variables of clinical importance. Omeprazole is superior to ranitidine in the short-term treatment of reflux oesophagitis.

The effect of 20 Mg omeprazole daily on serum gastrin, 24-h intragastric acidity, and bile acid concentration in duodenal ulcer patients

Serum gastrin, 24-h intragastric acidity, and bile acid concentrations were measured during physiologic conditions in 10 patients with duodenal ulcer disease. Omeprazole, 20 mg daily, for 8 days reduced acidity by greater than or equal to 99% in six patients and by 47-54% in four patients. The degree of acid reduction was related to the area under the plasma omeprazole concentration time curve (AUC). Serum gastrin levels were not significantly increased by omeprazole. Intragastric bile acid concentrations were increased by omeprazole, but this seems to be of little importance for the healing of duodenal ulcers.