Variability in individual response to various doses of omeprazole. Implications for antiulcer therapy

Proton pump inhibitors: use and misuse in the clinical setting

INTRODUCTION

The introduction of proton pump inhibitors (PPIs) into clinical practice has greatly improved our therapeutic approach to acid-related diseases for their efficacy and safety. Areas Covered: The following evidence-based indications for PPI use are acknowledged by many scientific societies: treatment of the various forms and complications of gastroesophageal reflux disease, eradication of H. pylori infection in combination with two or more antibiotics, short- and long-term therapy of H. pylori-negative peptic ulcers, healing, and prevention of NSAID/COXIB-associated gastric ulcers, co-therapy with endoscopic procedures to control upper digestive bleeding and medical treatment of Zollinger Ellison syndrome. Expert Commentary: Despite the above well-defined indications, however, the use of PPIs continues to grow every year in both western and eastern countries and the endless expansion of the PPI market has created important problems for many regulatory authorities for two relevant features: the progressive increase of the costs of therapy and the greater potential harms for the patients. The major reasons for the misuse of PPIs are the prevention of gastro-duodenal ulcers in patients without risk factors and the stress ulcer prophylaxis in non-intensive care units, steroid therapy alone, anti-platelet or anti-coagulant treatment in patients without risk of gastric injury and the overtreatment of functional dyspepsia.

Effect of low-dose rabeprazole and omeprazole on gastric acidity: results of a double blind, randomized, placebo-controlled, three-way crossover study in healthy subjects

BACKGROUND

The treatment of acid-related symptoms requires rapid and consistent acid suppression, especially with on-demand regimens.

AIM

To compare the antisecretory activity of low-dose rabeprazole and omeprazole in healthy, Helicobacter pylori-negative subjects.

METHODS

In this randomized, double-blind, placebo-controlled, three-way crossover study, 27 volunteers were given rabeprazole 10 mg, omeprazole 10 mg, or placebo once daily for 7 days with a 10-14-day washout between treatments. Intragastric pH was monitored for 24-h on days 1 and 7 of each treatment.

RESULTS

Median gastric pH was significantly higher with rabeprazole than with omeprazole or placebo: day 1: 2.3, 1.4 and 1.3, respectively (P = 0.0056, rabeprazole vs. omeprazole; P < 0.0001, rabeprazole vs. placebo); day 7: 3.7, 2.2 and 1.3, respectively (P = 0.0016 rabeprazole vs. omeprazole; P < 0.0001, rabeprazole vs. placebo). Time with gastric pH above 4 was significantly higher with rabeprazole than with omeprazole: day 1, 5.8 h vs. 3.7 h, respectively (P < 0.02); day 7, 10.5 h vs. 4.6 h, respectively (P = 0.0008).

CONCLUSIONS

Rabeprazole 10 mg provides more rapid acid inhibition compared with omeprazole 10 mg. After 7 days, the time with pH above 4 is more than doubled with rabeprazole 10 mg vs. omeprazole 10 mg.

The choice of proton pump inhibitor: does it matter?

Proton pump inhibitors are used at different dosages for the treatment of acid-related gastrointestinal disorders, such as gastro-oesophaeal reflux and peptic ulcer disease. Comparisons of four different proton pump inhibitors: lansoprazole, omeprazole, pantoprazole, and rabeprazole show that they all have similar potency and efficacy. Rabeprazole, however, displays a slightly more rapid onset of acid inhibition than the others; the clinical advantage of this seems limited. The S-isomer of omeprazole, esomeprazole, exhibits a somewhat higher potency than the other proton pump inhibitors. Reports supporting a clinical advantage of this property are not convincing. To conclude, all inhibitors seem comparable as regards inhibition of gastric acid secretion.

Unsolved problems in the management of patients with gastro-oesophageal reflux disease

Gastro-oesophageal reflux disease is a common problem that brings large numbers of patients to physicians every day. It lowers the quality of life of affected individuals and exposes them to potentially dangerous complications. An increasing awareness exists among patients, doctors and authorities about the relevance of this pathological condition. Despite an improved understanding of many aspects of gastro-oesophageal reflux disease, clinical management of several cases is still unsatisfactory. Atypical cases with extra-oesophageal manifestations often defy diagnosis. Even typical symptoms are often misunderstood and considered to be part of the poorly defined area of dyspepsia by both patients and doctors. As a consequence, management remains uncertain for too many cases. If correctly diagnosed, gastro-oesophageal reflux disease can be efficaciously treated with proton pump inhibitors (PPIs). Although standard doses of PPIs can heal mucosal lesions and provide symptom relief in the vast majority of oesophagitis patients, non-oesophagitis symptomatic individuals and those with extra-oesophageal manifestations may fail to respond to similar regimens. Antireflux surgery is a possible alternative to PPI therapy, but it is hampered by complications in a substantial percentage of cases and by sporadic casualties even when performed by experienced surgeons. The high prevalence of gastro-oesophageal reflux disease in the general population and the relatively high management costs should prompt any doctor to seek the best possible therapeutic approach.

Effective intra-oesophageal acid suppression in patients with gastro-oesophageal reflux disease: lansoprazole vs. pantoprazole

BACKGROUND

: Effective intra-oesophageal acid suppression is an important therapeutic goal in complicated and atypical gastro-oesophageal reflux disease.

AIM

: To compare the efficacy of lansoprazole and pantoprazole in normalizing oesophageal acid exposure.

METHODS

: Fifty patients with complicated or atypical gastro-oesophageal reflux disease were randomly assigned to receive 30 mg lansoprazole (n = 26) or 40 mg pantoprazole (n = 24) once daily. Three to four weeks after the start of treatment, patients underwent 24-h oesophageal pH monitoring whilst on therapy. If the results were improved but still abnormal, the dosage was doubled and pH monitoring was repeated. If oesophageal acid exposure was not improved, the patient was shifted to the alternative drug regimen.

RESULTS

: Oesophageal acid exposure was normalized in all 26 patients treated with lansoprazole (in 35% of cases with a double daily dosage), whereas in six of the 24 (25%) patients treated with pantoprazole it was neither normalized nor lowered (P = 0.008). Accordingly, the mean percentage acid reflux time was significantly lower for the lansoprazole group (2.1) than for the pantoprazole group (5.8) (P = 0.032).

CONCLUSIONS

: Effective intra-oesophageal acid suppression can be accomplished more reliably with lansoprazole than with pantoprazole in patients with complicated and atypical gastro-oesophageal reflux disease.

Dose-dependent control of intragastric pH by pantoprazole, 10, 20 or 40 mg, in healthy volunteers

BACKGROUND

Proton pump inhibitors have emerged as the most effective class of drugs for the treatment of gastro-oesophageal reflux. Pantoprazole is a proton pump inhibitor that has demonstrated high clinical efficacy.

AIM

To evaluate the effect of once-daily doses of pantoprazole, 10, 20 and 40 mg, on gastric acidity in healthy volunteers.

METHODS

Thirty-six subjects received pantoprazole in a three-way crossover design study. Ambulatory 24-h intragastric pH and distal oesophageal pH were monitored at baseline and on the last day of each treatment period. The measured endpoints were the median intragastric and oesophageal pH, the percentage of time the intragastric pH < 4 and oesophageal pH < 4 and the area under the curve for gastric acidity over 24 h. Safety was evaluated by incidence and severity of adverse events.

RESULTS

Pantoprazole demonstrated a linear dose- dependent suppression of gastric acidity over the dose range 10-40 mg. The dose of 40 mg demonstrated a significantly greater response than the lower doses, particularly at night. All pantoprazole doses were well tolerated.

CONCLUSIONS

Pantoprazole demonstrates a dose-related effect in the range 10-40 mg once daily. The once-daily dose of 40 mg provides the highest and most consistent control of gastric pH, especially at night.

Lansoprazole vs. omeprazole for gastro-oesophageal reflux disease: a pH-metric comparison

BACKGROUND

Lansoprazole and omeprazole are widely used proton pump inhibitors for the management of gastro-oesophageal reflux. Normalization of oesophageal acid exposure is an important goal in the management of complicated and atypical gastro-oesophageal reflux disease.

AIM

To compare the efficacy of lansoprazole and omeprazole in the abolition of abnormal reflux as assessed by oesophageal pH monitoring.

METHODS

Seventy patients with complicated or atypical gastro-oesophageal reflux disease were randomly assigned to receive 30 mg lansoprazole or 20 mg omeprazole once daily. Three to four weeks after the start of treatment, patients underwent oesophageal pH monitoring while on therapy. If the results were still abnormal, the proton pump inhibitor dosage was doubled and 24-h pH-metry was repeated after 20-30 days.

RESULTS

Thirty-six patients were randomized to receive lansoprazole and 34 patients to receive omeprazole. Ten of the 36 (29%) patients treated with 30 mg lansoprazole once daily and 23 of the 34 (68%) patients treated with 20 mg omeprazole once daily had persistently abnormal reflux at oesophageal pH monitoring (P < 0.001). In all such cases, repeat pH monitoring after doubling the proton pump inhibitor dosage gave normal results.

CONCLUSIONS

At the currently marketed dosages of lansoprazole and omeprazole, normalization of oesophageal acid exposure in patients is accomplished more easily with lansoprazole.

Comparable clinical efficacy and tolerability of 20 mg pantoprazole and 20 mg omeprazole in patients with grade I reflux oesophagitis

BACKGROUND

Several clinical trials have shown that pantoprazole (40 mg) and omeprazole (40 or 20 mg) have similar efficacy and safety in the treatment of grade II-IV reflux oesophagitis (Savary-Miller classification).

AIM

To compare the efficacy and safety of once-daily doses of pantoprazole (20 mg) and omeprazole (20 mg) with respect to symptom relief and healing of patients with grade I reflux oesophagitis.

METHODS

Patients with endoscopically established grade I reflux oesophagitis (non-confluent, patchy red lesions with/without white fibrin coating) were enrolled into this randomized, open, parallel-group, multicentre study. A total of 328 patients (n=166 in the pantoprazole group, n=162 in the omeprazole group) were recruited in 23 centres. Patients received 4 weeks of treatment. If the reflux oesophagitis was not completely healed, the treatment was extended to 8 weeks.

RESULTS

After 2 and 4 weeks of treatment with either pantoprazole or omeprazole, the rate of symptom relief was similar (70% vs. 79% and 77% vs. 84%, respectively). High healing rates were observed after 4 and 8 weeks (pantoprazole: 84% and 90%, respectively; omeprazole: 89% and 95%, respectively). Both treatments were well tolerated. The most frequently reported adverse events on pantoprazole and omeprazole, respectively, were nausea (8% vs. 7%), diarrhoea (5% vs. 6%) and headache (6% vs. 3%).

CONCLUSIONS

After 4 and 8 weeks of treatment with pantoprazole (20 mg) or omeprazole (20 mg), patients with mild gastro-oesophageal reflux disease (grade I) showed comparably high rates of symptom relief and healing. Both treatments were safe and well tolerated.

Histamine receptor antagonists, proton pump inhibitors and their combination in the treatment of gastro-oesophageal reflux disease

The medical treatment of gastro-oesophageal reflux disease is accomplished with the appropriate use of anti-secretory therapy, principally H(2)-receptor antagonists and proton pump inhibitors. In fact, there is a direct correlation between the length of time, in terms of the number of hours per day that the intragastric pH is above 4, and the healing of the oesophagitis. Nowadays, H(2)-receptor antagonists are of limited use as primary treatment, being inferior to proton pump inhibitors in both healing and symptom relief. Although the majority of patients can be effectively managed with carefully titrated doses of proton pump inhibitors, a small number will continue to show difficulty in the management of their disease, principally because of inadequate nocturnal acid control. These patients may benefit from a combination of proton pump inhibitors twice daily with an H(2)-receptor antagonist at bedtime. This article reviews the use of H(2)-antagonists, proton pump inhibitors and their combination in the management of the patient with gastro-oesophageal reflux disease.

Effects of omeprazole on intragastric pH and plasma gastrin are dependent on the CYP2C19 polymorphism

BACKGROUND & AIMS

Omeprazole is metabolized by cytochrome P450 (CYP2C19). The activity of this enzyme is polymorphic, with incidences of poor metabolizers (PMs), heterozygous extensive metabolizers (EMs), and homozygous EMs in white populations of 3%, 30%, and 67%, respectively. The importance of the CYP2C19 polymorphism for the effects of omeprazole on intragastric pH and plasma gastrin concentrations has been investigated.

METHODS

Twenty-five white patients were genotyped for CYP2C19 by allele-specific polymerase chain reaction amplification, and their Helicobacter pylori status was assessed by serology and with immunoblot analysis. Intragastric pH was monitored over 24 hours, and meal-stimulated plasma gastrin concentration was measured over 4 hours (AUC 4h) before (day 0) and during (day 8) treatment with 20 mg omeprazole once daily.

RESULTS

Eleven patients were homozygous for the wild-type allele (wt/wt), 12 were heterozygous EMs (wt/mut), and 2 were PMs (mut/mut). Median (95% confidence interval) 24-hour intragastric pH in the heterozygous EM group was 5.5 (range, 5.1-5. 9) compared with 3.1 (range, 2.7-3.6) in homozygous EMs (P < 0.0001) at day 8. The percentage of time with intragastric pH > 4 at day 8 was significantly higher in the wt/mut than wt/wt group (72.4% vs. 37.1%; P < 0.0001). H. pylori status had less influence than CYP2C19 on intragastric acidity. Omeprazole treatment increased meal-stimulated plasma gastrin concentrations from day 0 to day 8 in the homozygous EMs and heterozygous EMs by 16% (NS) and 157% (P = 0. 002), respectively. In heterozygous EMs, the gastrin increase was more pronounced in the H. pylori-positive group (226%) than H. pylori-negative group (80%; P = 0.02).

CONCLUSIONS

The effects of omeprazole on intragastric pH and plasma gastrin are dependent on the CYP2C19 polymorphism in patients with acid-related disorders.

A placebo-controlled study to assess the effects of 7-day dosing with 10, 20 and 40 mg rabeprazole on 24-h intragastric acidity and plasma gastrin in healthy male subjects

AIM

To compare the effects of rabeprazole 10, 20 and 40 mg o.d. on 24-h intragastric acidity and plasma gastrin concentration in a randomized, double-blind placebo-controlled trial.

METHODS

Twenty-four healthy male volunteers were studied on the 7th day of morning dosing with either placebo or rabeprazole 10, 20 or 40 mg in a crossover fashion. On day 7, hourly intragastric acidity was measured for 24 h from 08.00 hours by gastric aspiration. Plasma gastrin concentrations were also measured hourly from 08.00 to 24.00 hours, and 2-hourly thereafter.

RESULTS

Compared with placebo, rabeprazole 10, 20 and 40 mg produced significant dose-related decreases in intragastric acidity (median 24-h integrated acidity=697, 186, 129 and 82 mmol h/L, respectively). This was associated with significant elevation of plasma gastrin concentration (median 24-h integrated gastrin=141, 1184, 1484 and 1763 pmol.h/L, respectively). Rabeprazole 40 mg resulted in significantly decreased acidity compared with both 10 and 20 mg, and in longer times for which intragastric pH was maintained at > 3 (19. 2 h vs. 17.3 h and 17.5 h) and > 4 (17 h vs. 14.2 h and 15.2 h), but was accompanied by significantly increased plasma gastrin. There was a consistent trend for greater antisecretory activity for 20 mg compared with 10 mg, but these differences did not reach statistical significance. The interindividual variability in antisecretory response was greatest with 10 mg.

CONCLUSIONS

Rabeprazole 10, 20 and 40 mg produce significant, profound dose-related inhibition of gastric acid secretion. Taking into account reciprocal increases in plasma gastrin and the interindividual variation in antisecretory response, 20 mg appears to be the preferred dose for routine clinical use.

Effect of gastric acid suppression on 13C-urea breath test: comparison of ranitidine with omeprazole

BACKGROUND

The assessment of the effect of H2 antagonists on the results of the urea breath test has produced controversial results.

AIM

To assess whether standard doses of both omeprazole and H2 blockers can adversely influence the accuracy of the urea breath test.

METHODS

Sixty dyspeptic patients with ascertained Helicobacter pylori infection were recruited for this prospective, open study. They were randomized to receive either omeprazole 20 mg at 08:00 hours (n = 30) or ranitidine 300 mg at 22:00 hours (n = 30) for 14 days. The urea breath test was performed at baseline, on day 14, while patients were still taking the antisecretory drugs, and on day 21, 1 week after their cessation. Duplicate breath samples were collected after ingestion of 75 mg 13C-urea + citric acid. A delta value > 5 per thousand was considered positive.

RESULTS

On day 14 the median delta values had declined, but not significantly (P = 0. 07) compared to baseline (13.79 vs. 22.39) with omeprazole, while they had increased (P = 0.27) with ranitidine (27.21 vs. 19.46). On the same day there were five out of 30 (17%) and five out of 28 (18%) false-negative results in the omeprazole and ranitidine groups, respectively. All these cases became positive again on day 21. However, in eight cases treated with omeprazole and 13 treated with ranitidine, there was an increase of 14-day delta values compared to baseline.

CONCLUSIONS

Our study shows that both omeprazole and ranitidine at standard doses are able to negatively affect the results of the urea breath test. Their adverse effect resolves within 7 days of drug cessation and therefore the withdrawal of these drugs 7 days before testing seems to be sufficient to avoid false-negative results. The surprising finding that both antisecretory drugs reduce delta values in one group and increase them in another group of patients deserves further study.

Diagnostic evaluation in gastroesophageal reflux disease

Gastroesophageal reflux disease (GERD) describes the clinical manifestations of reflux of gastric contents and the associated symptoms and patterns of tissue injury. Although its exact prevalence is difficult to determine, there is no doubt the GERD is the most common esophageal disease and probably among the most prevalent conditions seen in the primary care setting. GERD has a wide clinical spectrum, making the diagnostic evaluation challenging and complicated at times. Confirmatory test are rarely needed in patients with typical symptoms of heartburn or regurgitation who have a good clinical response to GERD therapy. This article describes the diagnostic tests necessary for some cases of GERD.

Comparison of 24-h control of gastric acidity by three different dosages of pantoprazole in patients with duodenal ulcer

BACKGROUND

It is now clear that the extent to which gastric acid secretion must be suppressed varies with the clinical condition being treated.

AIM

To assess the 24-h control of gastric acidity and the individual response variability of three different doses of pantoprazole.

METHODS

Sixty-four duodenal ulcer patients were recruited for this prospective, randomized, multicentre, double-blind, parallel-group study. They were subdivided into three well-matched groups treated with 20 mg o.m., 40 mg o.m. and 40 mg b.d. of pantoprazole, respectively. Endoscopy and intragastric pH monitoring were performed in each patient before and after 14 days of treatment.

RESULTS

Fifty-five patients were eligible for final analysis (17 treated with 20 mg o.m., 18 with 40 mg o.m. and 20 with 40 mg b.d. pantoprazole). The ulcer crater healed in 94, 88 and 95% of cases, respectively. The three dosages of pantoprazole produced significant increases in gastric pH compared to basal levels (P < 0.0001). There was also a clear dose-dependent pharmacodynamic effect, which augmented on moving from the lowest dosage of 20 mg o.m. pantoprazole to the highest dosage of 40 mg b.d. (P < 0.01-0.001). The inter-individual response variability within the three treatment groups was more marked with the dose of 20 mg than with the two higher doses of pantoprazole.

CONCLUSIONS

All three doses of pantoprazole we tested are highly effective in decreasing gastric acidity and there is a clear dose-dependent pharmacodynamic effect on moving from the lowest to the highest dosage. The greatest inter individual variation in the degree of acid inhibition was seen with pantoprazole 20 mg o.m., while the majority of patients responded adequately to the two higher doses of the drug.

Physiochemical and physiological mechanisms for the effects of food on drug absorption: the role of lipids and pH

Drugs are absorbed after oral administration as a consequence of a complex array of interactions between the drug, its formulation, and the gastrointestinal (GI) tract. The presence of food within the GI tract impacts significantly on transit profiles, pH, and its solubilization capacity. Consequently, food would be expected to affect the absorption of co-administered drugs when their physicochemical properties are sensitive to these changes. The physicochemical basis by which ingested food/lipids induce changes in the GI tract and influence drug absorption are reviewed. The process of lipid digestion is briefly reviewed and considered in the context of the absorption of poorly water-soluble drugs. The effect of food on GI pH is reviewed in terms of location (stomach, upper and lower small intestine) and the temporal relationship between pH and drug absorption. Case studies are presented in which postprandial changes in bioavailability are rationalized in terms of the sensitivity of the physicochemical properties of the administered drug to the altered GI environment.

Partial regression of Barrett's esophagus by long-term therapy with high-dose omeprazole

BACKGROUND

Barrett's esophagus is mainly regarded as an acquired condition related to increased gastroesophageal reflux. Thus it is conceivable that abolition of acid reflux would lead to its regression. The aim of this study was to assess whether long-term treatment with high-dose omeprazole (60 mg/day) produces a consistent control of gastric acid production and normalizes the esophageal acid exposure, thus reducing the length of Barrett's epithelium.

METHODS

Fourteen patients (8 men and 6 women, mean age 52 years) with histologic diagnosis of columnar epithelium longer than 3 cm in the distal part of the esophagus were enrolled and began receiving 60 mg of omeprazole in a single daily morning dose. Before therapy and after 6 and 12 months of therapy, all patients had endoscopy with four-quadrant biopsies at 2 cm intervals. A 24-hour esophagogastric pH recording was performed at entry and after 10 days, 6 months, and 12 months of treatment in all patients.

RESULTS

The initial length of Barrett's epithelium (4.5 +/- 1.9 cm) was significantly reduced after 6 months (3.1 +/- 1.1; p < 0.01) and 12 months (2.1 +/- 1.6; p < 0.005) of treatment. Values were significantly lower at 12 than at 6 months (p < 0.03). The 24-hour mean gastric pH after 10 days (5.89 +/- 0.58), 6 months (5.71 +/- 0.55), and 12 months (5.54 +/- 0.76) of therapy was always higher (p < 0.001) than the basal level (1.9 +/- 0.49). No significant difference in gastric pH was seen over the treatment period. The 24-hour mean percent of time in which pH in the esophagus was below 4.0 decreased significantly (p < 0.001) from a basal rate of 29.4% to 3.5%, 3.0%, and 4.9% in the various time intervals of therapy. There was a normalization of esophageal acid exposure in all patients but two.

CONCLUSIONS

It can be concluded that the antisecretory effect of 60 mg/day of omeprazole is consistent and is kept constant throughout the entire 1-year treatment period. The consequent normalization of esophageal acid exposure in almost all patients in our series led to a partial, but significant, regression in the length of Barrett's epithelium.

Ethnic and genetic determinants of omeprazole disposition and effect

OBJECTIVES

To compare the pharmacokinetics and dynamics of omeprazole in white and Chinese subjects.

METHODS

This double-blind two-stage study, performed in the clinical research center of a university hospital, evaluated 15 healthy nonsmoking men (eight white subjects and seven Chinese extensive metabolizers of mephenytoin). Blood samples were obtained over 24 hours after the eighth omeprazole dose (40 mg/day). Omeprazole, omeprazole sulfone, and hydroxyomeprazole pharmacokinetics were calculated from the respective plasma concentration-time curves. Twelve- and 24-hour integrated plasma gastriun (AUCgas12 and AUCgas24) were calculated from the respective plasma gastrin concentrations. A week before the initiation of omeprazole the activities of CYP2D6, CYP2C19, and CYP3A4 were determined by previously established methods.

RESULTS

Omeprazole concentrations were significantly lower (mean area under the plasma concentration time curve extrapolated to infinity [AUCO-infinity] +/- SEM; 7.53 +/- 1.21 versus 12.80 +/- 2.13 mumol.hr.L-1, respectively; p < 0.05) and its oral clearance greater (319 +/- 60 versus 183 +/- 35 ml/min, respectively; p < 0.05) in the white subjects than in the Chinese subjects. Omeprazole and omeprazole sulfone AUCO-infinity values were well correlated with the S/R mephenytoin ratio (r = 0.82 and r = 0.84, respectively; p < 0.001) and with urinary 4'-hydroxymephenytoin (r = -0.58 [p < 0.03] and r = -0.52 [p < 0.02], respectively). Fasting gastrin, AUCgas12, and AUCgas24 were significantly greater in the Chinese subjects than in the white subjects (30.0 +/- 6.4 versus 14.4 +/- 1.2 pmol, respectively [p < 0.02]; 661 +/- 114 versus 334 +/- 38 pmol.hr.L-1, respectively [p < 0.002]; and 1414 +/- 228 versus 747 +/- 99 pmol.hr.L-1, respectively [p < 0.004]). In addition, the S/R mephenytoin ratio and omeprazole AUCO-infinity correlated with the extent of omeprazole induced hypergastrinemia.

CONCLUSION

The metabolism of omeprazole and the rise in gastrin concentration after its administration is genetically determined and ethnically dependent.

Relation between oesophageal acid exposure and healing of oesophagitis with omeprazole in patients with severe reflux oesophagitis

BACKGROUND/AIMS

Reducing oesophageal acid exposure by suppressing acid secretion with omeprazole is highly effective in healing reflux oesophagitis. Some patients with severe oesophagitis, fail to heal and whether this results from inadequate acid suppression or other factors is unclear. The aim of this study, was to investigate the relation between oesophageal acid exposure and healing in patients with severe reflux oesophagitis treated with omeprazole.

METHODS

Sixty one patients with grade 3 or 4 ulcerative oesophagitis were treated for eight weeks with omeprazole 20 mg every morning. Those patients unhealed at eight weeks were treated with 40 mg every morning for a further eight weeks. Endoscopy and 24 hour oesophageal pH monitoring were performed before treatment and at the end of each treatment phase while receiving treatment.

RESULTS

Thirty per cent of patients failed to heal with the 20 mg dose. Unhealed patients had greater total 24 hour oesophageal acid exposure before treatment, and while receiving treatment also had greater acid exposure and a smaller reduction in acid exposure than did patients who healed. Forty seven per cent of the unhealed patients also failed to heal with the 40 mg dose. These patients had similar levels of acid exposure before treatment to those who healed, but had greater acid exposure while receiving treatment, particularly at night when supine.

CONCLUSIONS

Patients with severe ulcerative oesophagitis who are refractory to omeprazole have greater oesophageal acid exposure while receiving treatment than responding patients. This is due to a reduced responsiveness to acid suppression, and is likely to be an important factor underlying the failure of the oesophagitis to heal.

Omeprazole in the long-term treatment of gastro-oesophageal reflux disease. A double-blind randomized dose-finding study

BACKGROUND

Omeprazole is effective in the treatment of reflux oesophagitis, and it is important to determine the lower dose limit with still appropriate clinical efficacy.

METHODS

Patients with endoscopic oesophagitis grade 1-4 (N = 220) were randomized to double-blind treatment with 20 mg or 40 mg omeprazole daily for 4-8 weeks. Those healed after this initial treatment phase were re-randomized to double-blind treatment with 20 mg omeprazole daily (n = 67), 10 mg omeprazole daily (n = 68), or placebo (n = 33) for 6 months. Remission was defined as the absence of any endoscopic sign of oesophagitis.

RESULTS

Healing rates were increased with 40 mg omeprazole, the therapeutic gain compared with the 20-mg dose being 15% after 4 and 8 weeks. The proportion of patients in remission after 6 months was 59% with 20 mg omeprazole, 35% with 10 mg omeprazole, and 0% with placebo.

CONCLUSION

Maintenance treatment with 10 mg omeprazole can prevent recurrence of oesophagitis in about one-third of patients with all grades of oesophagitis, and 20 mg omeprazole in about twice as many.

Omeprazole 10 mg or 20 mg once daily in the prevention of recurrence of reflux oesophagitis. Solo Investigator Group

This study determined the optimal maintenance dose of omeprazole in reflux oesophagitis. One hundred and ninety three patients rendered asymptomatic and healed after four or eight weeks omeprazole were randomised double blind to 10 mg omeprazole once daily (n = 60 evaluable), 20 mg omeprazole once daily (n = 68), or placebo (n = 62) for one year or until symptomatic relapse. Each omeprazole regimen was superior to placebo in preventing both symptomatic relapse (life table analysis, p < 0.001) and endoscopically verified relapse (p < 0.001). At 12 months, the life table endoscopic remission rates (proportions of patients without grade > or = 2 oesophagitis) were: 50% (95% confidence intervals 34 to 66%) with 10 mg omeprazole once daily, 74% (62 to 86%) with 20 mg omeprazole once daily, and 14% (2 to 26%) with placebo. At 12 months, the life table symptomatic remission rates (proportions of patients asymptomatic or with mild symptoms) were: 77% (64 to 89%) with 10 mg omeprazole once daily, 83% (73 to 93%) with 20 mg omeprazole once daily, and 34% (16 to 52%) with placebo. Both 10 mg and 20 mg omeprazole once daily were effective in prolonging the remission of reflux oesophagitis: 10 mg may be appropriate to start longterm treatment, though the existence of a dose response relation means that 20 mg once daily may be effective in patients for whom 10 mg once daily is suboptimal.

Antisecretory effects of three omeprazole regimens for maintenance treatment in duodenal ulcer

This study was carried out to assess the antisecretory effects and their possible changes over time of three different dose regimens of omeprazole that could be proposed for maintenance treatment in duodenal ulcer. Forty-five patients with endoscopically proven duodenal ulcer were studied by means of 24-hr gastric pH-metry both in basal conditions and on the fifth day of acute treatment with omeprazole 20 mg in the morning. Ulcers healed after four weeks (in three cases after eight weeks) and afterwards, 15 patients were randomized to receive orally at 0800 hr in single-blind fashion omeprazole 10 mg daily (group A), 15 to receive omeprazole 40 mg on Saturday and Sunday followed by a five-day period without medication (group B), and 15 to receive omeprazole 20 mg every other day (group C) for up to three months. On the 20th and 80th days of these maintenance treatments 24-hr gastric pH-metry was repeated to assess the antisecretory effectiveness of each regimen over a two-month period. In patients of group B these tests began at 1700 hr on Friday, the last of five days off treatment, and in those of group C at 1700 hr of the day off medication. All three dose regimens of omeprazole were able to raise pH values significantly (P < 0.01-0.001) compared to basal levels. Omeprazole 20 mg every other day was more effective (P < 0.01) than omeprazole 40 mg weekend, but did not differ significantly from omeprazole 10 mg daily. The durations of acid inhibition (pH > 3.0 units/24 hr) were 12.44, 10.00, and 17.38 hr with groups A, B, and C, respectively. There was no significant difference between the pH profiles of the 20th and 80th days with every dose regimen. It is concluded that all three dose regimens of omeprazole are effective in reducing gastric acidity and their pharmacodynamic action does not change with time. Therefore they are suitable to be assessed in large clinical trials aimed at verifying the prevention of duodenal ulcer recurrence for longer periods.