Inhibitory action of lansoprazole and its analogs against Helicobacter pylori: inhibition of growth is not related to inhibition of urease

A cell-based high-throughput screen identifies drugs that cause bleeding disorders by off-targeting the vitamin K cycle

Drug-induced bleeding disorders contribute to substantial morbidity and mortality. Antithrombotic agents that cause unintended bleeding of obvious cause are relatively easy to control. However, the mechanisms of most drug-induced bleeding disorders are poorly understood, which makes intervention more difficult. As most bleeding disorders are associated with the dysfunction of coagulation factors, we adapted our recently established cell-based assay to identify drugs that affect the biosynthesis of active vitamin K-dependent (VKD) coagulation factors with possible adverse off-target results. The National Institutes of Health (NIH) Clinical Collection (NCC) library containing 727 drugs was screened, and 9 drugs were identified, including the most commonly prescribed anticoagulant warfarin. Bleeding complications associated with most of these drugs have been clinically reported, but the pathogenic mechanisms remain unclear. Further characterization of the 9 top-hit drugs on the inhibition of VKD carboxylation suggests that warfarin, lansoprazole, and nitazoxanide mainly target vitamin K epoxide reductase (VKOR), whereas idebenone, clofazimine, and AM404 mainly target vitamin K reductase (VKR) in vitamin K redox cycling. The other 3 drugs mainly affect vitamin K availability within the cells. The molecular mechanisms underlying the inactivation of VKOR and VKR by these drugs are clarified. Results from both cell-based and animal model studies suggest that the anticoagulation effect of drugs that target VKOR, but not VKR, can be rescued by the administration of vitamin K. These findings provide insights into the prevention and management of drug-induced bleeding disorders. The established cell-based, high-throughput screening approach provides a powerful tool for identifying new vitamin K antagonists that function as anticoagulants.

Modified Helicobacter test using a new test meal and a 13C-urea breath test in Helicobacter pylori positive and negative dyspepsia patients on proton pump inhibitors

AIM

To determine the sensitivity and specificity of the ¹³C-urea breath test (UBT) in patients taking proton pump inhibitors (PPIs), using a new test meal Refex.

METHODS

One hundred and fourteen consecutive patients with dyspepsia, 53 Helicobacter pylori (H. pylori) positive, 49 H. pylori negative, were included in the study. The patients were then given esomeprazole 40 mg for 29 consecutive days, and the ¹³C-UBT with the new test meal was performed the next morning.

RESULTS

The sensitivity of the ¹³C-UBT with a cut off 2.5‰ was 92.45% (95%CI: 81.79%-97.91%) by per-protocol (PP) analysis and 78.13% (95%CI: 66.03%-87.49%) by intention-to-treat (ITT) analysis. The specificity of the ¹³C-UBT test was 96.00% in the ITT population (95%CI: 86.29%-99.51%) and 97.96% in the PP population (95%CI: 89.15%-99.95%).

CONCLUSION

The new test meal based ¹³C-UBT is highly accurate in patients on PPIs and can be used in those unable to stop their PPI treatment.

Negative Effect of Proton-pump Inhibitors (PPIs) on Helicobacter pylori Growth, Morphology, and Urease Test and Recovery after PPI Removal--An In vitro Study

BACKGROUND

Proton-pump inhibitor (PPI) consumption does lead to false-negative results of Helicobacter pylori diagnostic tests such as biopsy culture and rapid urease test (RUT).

MATERIALS AND METHODS

Helicobacter pylori isolates from 112 dyspeptic patients with (56.5%) or without (43.5%) PPI consumption were recruited for examining the negative effects of omeprazole (OMP), lansoprazole (LPZ), and pantoprazole (PAN) on H. pylori viability, morphology, and urease, in vitro. The effect of a sublethal concentration of OMP on bacterial features and their recovery after removal of OMP was also assessed.

RESULTS

Of 112 culture-positive gastric biopsies, 87.5% were RUT positive and 12.5% RUT negative. There was a significant correlation between negative RUT results and PPI consumption (p < .05). OMP (minimum inhibitory concentration, MIC 32 μg/mL) and LPZ (MIC 8 μg/mL) inhibited the growth of 78.6% of H. pylori isolates. OMP and LPZ inhibited urease of 90.3% of isolates between 0 and 40 minutes and 54.4% between 20 and 40 minutes, respectively. PAN did not inhibit H. pylori growth and urease. Three 3-day (9 days) consecutive subcultures of H. pylori on brucella blood agar (BBA) supplemented with OMP resulted in reduced bacterial viability (1+), compared with control (4+), change of spiral morphology to coccoid, and reduction in pink color intensity in urea agar. Bacterial growth (1+), morphology, and urease test did not improve after the first 3-day and second 3-day (6 days) subcultures on BBA. However, relative recovery occurred after the third 3-day (9 days) subculture and complete recovery was observed after the fourth 3-day (12 days) subculture, as confluent growth (4+), 100% spiral cells, and strong urease test.

CONCLUSION

Proton-pump Inhibitors exert transient negative effects on H. pylori viability, morphology, and urease test. Accordingly, cessation of PPI consumption at least 12 days before endoscopy could help avoiding false-negative results of H. pylori diagnostic tests.

Real-world Helicobacter pylori diagnosis in patients referred for esophagoduodenoscopy: The gap between guidelines and clinical practice

BACKGROUND AND AIMS

Histopathology is the most accurate test to detect H. pylori when performed correctly with unknown validity in daily practice clinic settings. We aimed to determine the rate of potentially false-negative H. pylori results that might be due to continued use of proton pump inhibitors (PPIs) in routine endoscopy practice. We also aimed to establish whether gastroenterologists recommend routine cessation of PPIs before esophagogastroduodenoscopy (EGD) and whether they regularly document that biopsies for H. pylori testing have been taken while the patients are on PPI treatment.

METHODS

Detailed information about three known factors (PPIs, antibiotics and prior H. pylori eradication treatment), which may cause histology or rapid urease test (RUT) to be unreliable, had been prospectively collected through interviews using a questionnaire before each test. Gastric biopsies were stained with H&E for histological analysis.

RESULTS

A total of 409 individuals at three academic gastroenterology institutions were tested 200 times with histology. Fifty-six per cent (68 of 122) of all negative tests fell in the category of continuing PPI use, which had the potential to make the histology and RUT results unreliable.

CONCLUSIONS

These data demonstrate a clear and important gap between current guidelines and real-world practice with regards to the diagnosis of H. pylori during EGD. A negative histology or RUT should be considered false negative until potential protocol violations are excluded. Documentation of PPI use during the EGD should be an integral part of the EGD report. The current practice of taking biopsies for H. pylori testing in patients under PPIs should be reevaluated.

Lansoprazole Novel Effector Sites Revealed by Autoradiography: Relation to Helicobacter pylori, Colon, Esophagus and Others

Lansoprazole uptake sites by two kinds of autoradiographic procedures were compared with recent literature. The uptake sites have been seen in the Helicobacter pylori, colonic epithelial cells, inflammatory cells, peripheral autonomic nerves and enterochromaffinlike cells as well as gastric parietal cells. Each uptake sites corresponded to the reported localization of P-type ATPase or acidic compartment.

Ulcerative typhlocolitis associated with Helicobacter mastomyrinus in telomerase-deficient mice

Telomerase deficiency induces early senescence and defects in proliferating cell populations, but in mice it has not been associated with inflammatory bowel disease. Genetically engineered mice lacking either telomerase reverse transcriptase (TERT) or telomerase RNA were examined for chronic diarrhea and wasting. Affected mice had pasty stools, thickened nondistensible colon walls, and contracted ceca. Histologically, the cecal mucosa was largely replaced by inflammatory infiltrate consisting of plasma cells, neutrophils, lymphocytes, and macrophages with marked widespread fibrosis and ulceration. Remaining epithelium was disorganized and hyperplastic, with multifocal dysplasia. Colonic mucosa was markedly hyperplastic with similar inflammation and epithelial dysplasia. Multifocal adenomatous hyperplasia, but no inflammation, was present in the small intestine. Microaerophilic spiral bacteria with 16S rRNA gene sequences identical to Helicobacter mastomyrinus were isolated from the colon and cecum. Severe granulomatous typhlocolitis without epithelial dysplasia developed in germ-free recombination-activating gene (RAG) knockout (KO) recipients of CD4+ T cells and inoculated with cecal contents from affected TERT KO mice and in specific pathogen-free recipient RAG KO mice and interleukin-10 KO mice inoculated with H mastomyrinus. Typhlocolitis in mice given H mastomyrinus was more severe than in mice given Helicobacter hepaticus. Telomerase-deficient mice are susceptible to helicobacter-associated typhlocolitis. H mastomyrinus causes severe disease in susceptible mouse strains.

The early effect of proton pump inhibitor therapy on the accuracy of the 13C-urea breath test

BACKGROUND

The intake of proton pump inhibitors may interfere with the reliability of the urea breath test.

AIM

Prospective study to assess the accuracy of the urea breath test during the first days of therapy with proton pump inhibitors.

PATIENTS

Thirty patients who needed to start proton pump inhibitors therapy and 53 volunteers.

METHODS

A 13C-urea breath test was performed respectively before starting proton pump inhibitors therapy and every morning before its intake up until 10 days. The test was considered positive for values of 13CO2 > or = 3.0% delta over baseline. The coefficient of reproducibility for 95% interval of confidence of the urea breath test was calculated in both groups.

RESULTS

Of the 30 patients receiving proton pump inhibitors, 47% were positive for Helicobacter pylori. Among these, 43% developed false negative breath tests in the first 10 days. False positive results occurred in 37.5% of H. pylori-negative subjects in the first 10 days. The coefficient of reproducibility of the urea breath test was significantly higher in the group treated with proton pump inhibitors (11.0 versus 1.8 for the control group, p < 0.0001).

CONCLUSION

The intake of proton pump inhibitors impairs the accuracy of the 13C-urea breath test. False negative and false positive 13C-urea breath tests are common, occur as soon as after 1 day and increase with prolonged duration of treatment. The coefficient of reproducibility of the test in patients receiving proton pump inhibitors is not acceptable for clinical purpose and the test should not be performed once the medication has been started.

Masking of 13C urea breath test by proton pump inhibitors is dependent on type of medication: comparison between omeprazole, pantoprazole, lansoprazole and esomeprazole

BACKGROUND

The need to withhold acid suppression therapy while awaiting urea breath test results is a common clinical problem in symptomatic patients. It is unclear at present if the dose or type of proton pump inhibitor or the type of test meal govern the apparent masking effect of proton pump inhibitors on the urea breath test.

AIM

To prospectively evaluate Helicobacter pylori detection rates during treatment with four different proton pump inhibitors, utilizing a high-dose citric acid-based 13C urea breath test.

METHODS

Patients positive for Helicobacter pylori by urea breath test were randomized to receive either omeprazole 20 mg/day, pantoprazole 40 mg/day, lansoprazole 30 mg/day or esomeprazole 40 mg/day for 14 days. A repeat breath test was performed on day 14 of treatment.

RESULTS

One hundred and seventy-nine patients, mean age 45.8 +/- 16.8, completed the study. Treatment with omeprazole or pantoprazole prior to urea breath test (UBT) was associated with low false negative results, while lansoprazole and esomeprazole caused clinically unacceptable high false negative rates (pantoprazole 2.2% vs. lansoprazole 16.6%, P = 0.02, vs. esomeprazole 13.6%, P = 0.05; omeprazole 4.1% vs. lansoprazole 16.6%, P = 0.05).

CONCLUSIONS

Proton pump inhibitor-induced false negative results on high-dose citric acid based urea breath test vary with the type of proton pump inhibitor used. Selection of the appropriate test meal and proton pump inhibitor may allow symptomatic individuals to continue their proton pump inhibitors prior to performing a urea breath test.

False negative urea breath tests with H2-receptor antagonists: interactions between Helicobacter pylori density and pH

BACKGROUND

We studied the effects of famotidine, sodium bicarbonate, and citric acid on the 13C-urea breath test (UBT).

METHODS

Helicobacter pylori-infected volunteers received a UBT, 40 mg of famotidine at bedtime, and a second UBT (pudding test meal, 648 mg NaHCO3 tablet then 125 mg of urea in 200 ml of water containing 650 mg of NaHCO3). Experiment 2 consisted of four UBTs. Two were standard citric acid UBTs with 75 mg of urea and 2 g citric acid and two were sequential bicarbonate-citric acid UBTs. Sequential UBTs consisted of administration of a 648 mg bicarbonate tablet with 50 g of Polycose in 200 ml of water. Five minutes later, 125 mg of 13C-urea was given in 75 ml of water containing 650 mg of NaHCO3. Breath samples were collected after 15 minutes. Then, to acutely acidify the stomach, 4 g of citric acid was given in 200 ml of water. A second breath sample was collected 15 minutes after the citric acid. The standard UBTs were done before and after 6 days of famotidine (40 mg b.i.d.). Sequential UBTs were done after 1 and 6 days of famotidine therapy. Gastric biopsies for histology, culture, and mucosal cytokines were assessed before and after 6 days of famotidine.

RESULTS

Eighteen subjects participated, 10 in each experiment; seven had endoscopy with biopsy. Famotidine/ bicarbonate resulted an approximately 50% fall in UBT values (p = .021) with 10% becoming negative. The gastric pH increased from 5.1 +/- 0.5 to 6.7 +/- 0.2 (p = .03) although no pH value predicted the occurrence of false negative results. Under famotidine acid suppression, NaHCO3 reduced the delta over baseline (DOB) by 63% (p = .021). This was reversed with citric acid. Histology showed a H2-receptor antagonist-associated increase in the depth of gastric corpus inflammation.

CONCLUSIONS

H2-receptor antagonists differ from proton pump inhibitors as high intragastric pH may cause a reduction in urease activity, unrelated to a reduced bacterial load and reversed by citric acid.

Studies regarding the mechanism of false negative urea breath tests with proton pump inhibitors

OBJECTIVE

The mechanism of false negative urea breath tests (UBTs) results among proton pump inhibitor (PPI) users is unknown. We studied the time course of PPI-associated negative UBT, the relation to Helicobacter pylori density, and whether gastric acidification would prevent false negative UBT results.

METHOD

In the UBT experiment, H. pylori-infected volunteers received omeprazole 20 mg b.i.d. for 13.5 days. UBTs with citric acid were done before, after 6.5 days of PPI, and 1, 2, 4, 7, and 14 days after therapy. In the culture and histology experiment, after a wash-out of >5 months, nine of the original subjects were rechallenged with omeprazole for 6.5 days. Antral and corpus biopsies for histology and culture were done before and 1 day after PPI administration.

RESULTS

Thirty subjects (mean age 42 yr) were enrolled. UBTs were significantly reduced on day 6.5 (p = 0.031); 10 subjects (33%) developed transient negative UBTs. The UBT recovered in all but one subject by the fourth day post-PPI and in all subjects by day 14. In the culture and histology experiment, upon PPI rechallenge, three of nine subjects (33%) had negative UBTs. H. pylori density, whether measured by culture or histology, decreased with PPI therapy; antral biopsies became histologically negative in five subjects and corpus biopsies in three subjects.

CONCLUSION

PPI-induced negative UBT results were related to the anti-H. pylori effect of the PPI. Acidification of the stomach did not prevent false negative UBT results. Three days is likely the minimum delay from stopping PPI until one should perform a test for active infection. A delay of 14 days is preferred.

Different effects of short-term omeprazole, lansoprazole or pantoprazole on the accuracy of the (13)C-urea breath test

BACKGROUND

Proton pump inhibitors may interfere with the accuracy of the (13)C-urea breath test, but little information is available on the effect of standard doses of various proton pump inhibitors on this test.

AIM

To evaluate the effect of short-term standard doses of omeprazole, lansoprazole and pantoprazole on the accuracy of the standardized (13)C-urea breath test.

METHODS

A total of 124 patients with Helicobacter pylori infection, diagnosed on the basis of gastric histology, rapid urease test and (13)C-urea breath test, were studied. These patients received omeprazole, 20 mg/day, lansoprazole, 30 mg/day, or pantoprazole, 40 mg/day, for 2 weeks according to a randomized protocol. (13)C-Urea breath test was repeated on days 4, 7 and 14 while on therapy and 7 days after proton pump inhibitor withdrawal.

RESULTS

Of the patients receiving omeprazole and lansoprazole, 30% (12/40) and 20% (8/41), respectively, became (13)C-urea breath test negative during therapy, compared with none of the 42 patients treated with pantoprazole (P < 0.05). All the false negative (13)C-urea breath test results returned to positive within 1 week of drug withdrawal, with a mean recovery to 84.7 +/- 15.6% of baseline delta(13)CO(2).

CONCLUSIONS

Short-term omeprazole and lansoprazole interfere with the 13C-urea breath test, although a return to positive test results invariably occurs within 1 week of proton pump inhibitor withdrawal. In contrast, the accuracy of the (13)C-urea breath test does not appear to be significantly impaired by short-term pantoprazole, which therefore may not necessarily be withdrawn before this test.

Inhibitory activities of lansoprazole against respiration in Helicobacter pylori

Lansoprazole and its derivative AG-1789 dose-dependently inhibited cellular respiration by an endogenous substrate and decreased the ATP level in Helicobacter pylori cells. The inhibitory action of lansoprazole and AG-1789 against respiration was specific to substrates such as pyruvate and alpha-ketoglutarate and similar to the inhibitory action of rotenone, which is an inhibitor for the mitochondrial respiratory chain. Growth inhibition by lansoprazole and AG-1789 as well as by rotenone was augmented at high oxygen concentrations under atmospheric conditions. Since the 50% inhibitory concentrations of these compounds for the respiration were close to their MICs for H. pylori growth, the growth inhibition might be due to respiratory inhibition by these compounds.

Impaired development of HIV-1 gp160-specific CD8(+) cytotoxic T cells by a delayed switch from Th1 to Th2 cytokine phenotype in mice with Helicobacter pylori infection

Th1 and Th2 cells play a central role in immunoregulation during infection. We show that Helicobacter pylori induces Th1 cytokine responses early (2 weeks) but predominantly Th2 responses later (6 weeks) in infection. The switch is principally mediated by urease-specific CD4(+) T cells, and correlates with a loss of urease-specific high-avidity JNK(+) Th1 and gain of low-avidity JNK(-) (possibly Th2) cells at the later stage of infection, concomitant with a 100-fold higher colonization level of H. pylori at 6 weeks than at 2 weeks that might tolerize high-avidity Th1 cells. Furthermore, differentiation of HIV gp160-specific CD4(+) Th and CD8(+) cytotoxic T lymphocytes (CTL) into effector cells is impaired in 6-week H. pylori-infected mice immunized with vaccinia expressing gp160, and serum IL-12 stimulated by vaccinia infection is barely detectable. Adoptive transfer of urease-specific Th2 cells to mice infected only with gp160-expressing vaccinia abrogates Th1 polarization of the gp120 response, down-modulates virus-specific CTL responses, and delays virus clearance. Therefore, the H. pylori urease-mediated immunoregulation in the switch from JNK(+) Th1 to JNK(-) Th2 phenotype, and the preceding low IL-12 response, are likely critical steps in the impairment of antiviral immunity.

A short-term eradication therapy for Helicobacter pylori acute gastritis

BACKGROUND AND AIMS

Acute gastritis, caused by an initial infection of Helicobacter pylori (H. pylori), may resolve spontaneously, but the infection sometimes becomes chronic. We examined the efficacy of a short-term H. pylori eradication therapy on acute gastritis.

METHODS

Among the 15 patients with hemorrhagic acute gastritis who were randomly allocated to group A (eradication therapy) or group B (Lansoprazole, LPZ), 10 of them started to receive treatment within 1 day after the disease onset. The other five patients began the eradication therapy 4-6 days after disease onset (group C). Eradication therapy consisted of a daily oral administration of each of 30 mg lansoprazole (LPZ), once a day; 400 mg clarithromycin, twice a day; 1000 mg amoxicillin, twice a day; and 300 mg rebamipide, three times a day, for one week. If the endoscopy was normal, medication was stopped for the following 4 weeks before gastric endoscopy was performed again in order to assess H. pylori eradication.

RESULTS

All group A patients were cured after the 1-week treatment and therefore, they became H. pylori negative. Group B and C patients had erosions or ulcers after the 1-week treatment and so received an additional 3-week administration of LPZ. Four weeks later, their gastritis was cured and except for one group B patient, they became H. pylori-negative.

CONCLUSION

In patients with acute gastritis, caused by an initial H. pylori infection, eradication therapy was efficacious in achieving early healing. This therapy should be started as soon as possible after disease onset.

Unique mechanism of Helicobacter pylori for colonizing the gastric mucus

Helicobacter pylori is a human gastric pathogen causing chronic infection. Urease and motility using flagella are essential factors for its colonization. Urease of H. pylori exists both on the surface and in the cytoplasm, and is involved in neutralizing gastric acid and in chemotactic motility. H. pylori senses the concentration gradients of urea in the gastric mucus layer, then moves toward the epithelial surface by chemotactic movement. The energy source for the flagella movement is the proton motive force. The hydrolysis of urea by the cytoplasmic urease possibly generates additional energy for the flagellar rotation in the mucus gel layer.

The effect of dosing with omeprazole on the accuracy of the 13C-urea breath test in Helicobacter pylori-infected subjects

BACKGROUND

The 13C-urea breath test (13C-UBT) is an accurate means of Helicobacter pylori diagnosis. However, proton pump inhibitors may suppress H. pylori and cause false negative results.

AIM

To study the kinetics of H. pylori suppression by omeprazole during and after short-term use.

METHODS

Volunteers underwent a baseline 13C-UBT (13C-urea 100 mg). H. pylori-positive subjects took omeprazole 20 mg daily for 14 days. Those who remained 13C-UBT positive (delta13CO2 >/= 5) continued omeprazole for a further 14 days. 13C-UBTs were performed weekly on omeprazole and then every second day after it was stopped. False negatives occurred when delta13CO2 fell to < 5.

RESULTS

In 25 H. pylori-positive subjects (mean age 43.9 +/- 2.4 years; 21 females, 4 males) the mean baseline delta13CO2 was 28.1 +/- 3.4. False negative breath tests occurred in three subjects after 7 days of omeprazole and in a further four subjects after 14 days. A further six subjects developed negative tests between Days 14 and 28. Following cessation of omeprazole, the 13C-UBT became positive again in 12/13 subjects within 4 days and in all within 6 days, with a mean recovery to 99.9 +/- 18.6% of baseline delta13CO2.

CONCLUSIONS

False negative 13C-UBTs are common during treatment with omeprazole and occur after as little as 7 days. Return to positive test results is rapid after cessation of omeprazole. These findings are relevant to the timing of testing in clinical practice.

The effect of omeprazole dosing on the isolation of Helicobacter pylori from gastric aspirates

BACKGROUND

Animal experiments suggest that omeprazole dosing increases shedding of Helicobacter into the gastric lumen, and hence into gastric juice.

AIM

To assess the effect of omeprazole dosing on the yield of H. pylori from gastric aspirates of infected volunteers.

METHODS

Six serial nasogastric aspirates, three before and three during dosing with omeprazole 40 mg b.d., were obtained for culture from 10 H. pylori infected volunteers and one uninfected volunteer. To reduce contamination, samples were diluted 1:10 with Maximum Recovery Diluent (MRD; pH 7.0) or HCl-KCl buffer (pH 2.2) prior to culture on Columbia and Dent's agar.

RESULTS

Undiluted gastric juice cultures were rapidly overgrown by upper respiratory tract flora. HCl-KCl dilution resulted in isolation of H. pylori from 77% of infected subject aspirates before, and 67% of aspirates during dosing with omeprazole. The yields were significantly lower with MRD dilution, 47% and 10%, respectively. Omeprazole dosing significantly decreased the yield after MRD dilution, but not after HCl-KCl dilution.

CONCLUSIONS

Decreasing intragastric acidity, by dosing with omeprazole, decreases the isolation of H. pylori from routinely processed gastric aspirates. In vitro acidification of gastric aspirates, by HCl-KCl dilution, increases the isolation of H. pylori both before and during omeprazole dosing.

A novel tablet-based 13C urea breath test for Helicobacter pylori with enhanced performance during acid suppression therapy

BACKGROUND

The urea breath test (UBT) can still be improved in terms of user-friendliness and accuracy during acid-suppression therapy. This study was designed to evaluate a novel, rapidly disintegrating 13C UBT tablet, which was supplemented with citric acid to facilitate diagnosis of Helicobacter pylori in the hypochlorhydric stomach.

METHODS

The efficacy of a fasting 13C tablet-based UBT (TUBT) was compared with that of a standard 13C UBT (SUBT) during 40 min after dosing, and optimal sampling points were determined. The single-point TUBT was validated against a 'gold standard' (GS) including a TUBT, culture, histology, and a CLO test in 134 dyspeptic patients, and its optimal cut-off point was determined by means of a biometric method. In addition, 20 SUBT-positive patients were randomized to perform either the TUBT or the SUBT after 7 days of omeprazole therapy (20 mg twice daily).

RESULTS

Compared with a SUBT, the TUBT gave a quicker and wider separation between positive and negative results and an earlier optimal sampling point (10 versus 40 min). At 10 min the TUBT correctly classified 40 of 42 GS-positive subjects (sensitivity, 95%) and all of 92 GS-negative patients (specificity, 100%), and the optimal cut-off point was 1.8 delta per mil. Furthermore, when optimal sampling points were used, the TUBT (t = 10 min) proved to be more accurate than the SUBT (t = 40 min) during omeprazole treatment, correctly identifying all of 10 and 3 of 9 H. pylori-infected patients, respectively.

CONCLUSIONS

By supplying 13C urea and citric acid as a rapid-release tablet, it is possible to shorten the duration of the 13C UBT to 10 min, omit the test meal, and still maintain excellent accuracy, even during acid suppression therapy.

Treatment options for Helicobacter pylori infection when proton pump inhibitor-based triple therapy fails in clinical practice

BACKGROUND

The effectiveness of Helicobacter pylori eradication regimens has not been extensively investigated in the clinical practice setting. The optimal treatment choice after an initial failed eradication attempt has not been determined.

AIMS

To evaluate proton pump inhibitor-based triple therapies as first-line eradication regimens in clinical practice, and to establish the efficacy of second-line regimens in the context of an initial failed eradication attempt.

METHODS

Three hundred and eight patients with dyspepsia and evidence of H. pylori at endoscopy were recruited. As first-line therapy, 116 patients received omeprazole 20 mg b.d. in combination with amoxycillin 1 g b.d. and clarithromycin 500 mg b.d. (OAC) while 192 patients received omeprazole 20 mg b.d. in combination with metronidazole 400 mg b.d. and clarithromycin 250 mg b.d. (OMC). H. pylori status was reassessed at least 4 weeks after therapy (25 patients failed to attend for further testing). Of 52 patients with an initial failed eradication attempt, 20 patients received a 1 week quadruple therapy regimen incorporating omeprazole 20 mg b.d., tripotassium dicitrato bismuthate 120 mg q.d.s., tetracycline 500 mg q.d.s. and metronidazole 400 mg t.d.s., 20 patients received a 2-week proton pump inhibitor-based triple therapy regimen as described, and 12 patients received a further 1-week proton pump inhibitor-based triple therapy regimen.

RESULTS

Including 308 patients, the intention-to-treat (ITT) eradication rates for OAC and OMC as first-line regimens were 72% (95% CI: 63-80%) and 73% (95% CI: 67-79%) respectively. A per protocol (PP) analysis on the 283 patients who completed follow-up gives an initial eradication rate of 78% (95% CI: 69-86%) for OAC and 79% (95% CI: 73-85%) for OMC. There were 60 patients (21%; 95% CI: 17-26%) in whom the initial eradication attempt was unsuccessful. With second-line therapy, H. pylori was successfully eradicated in a further 35/52 (67%; 95% CI: 58-73%) patients. The eradication rates with the quadruple regimen and 2-week triple therapy regimens were 75% (95% CI: 56-94%) and 80% (95% CI: 63-98%) respectively (P = 0. 71). The eradication rate with a repeat 1-week regimen was 33% (95% CI: 7-60%).

CONCLUSIONS

The eradication rates achieved in this 'in practice' study with recommended first-line 1-week proton pump inhibitor-based triple therapy regimens were lower than the rates achieved with similar regimens in the clinical trial setting. A repeat 1-week proton pump inhibitor-based triple therapy regimen was not successful as a salvage therapy. Both the 2-week proton pump inhibitor-based triple therapy regimen and the 1-week quadruple therapy regimen were successful second-line treatments in >/=75% of patients.

Helicobacter pylori infection, chronic gastritis, and proton pump inhibitors

The proton pump inhibitors (PPIs) omeprazole, lansoprazole, and pantoprazole are widely used as antisecretory drugs and, in association with antibiotics, for the treatment of Helicobacter pylori infections. PPIs possess antibacterial activity against H. pylori in vitro, and may also exert an anti-inflammatory effect by interfering with the cellular immune response to infection. Their antimicrobial activity is selective for H. pylori. Lansoprazole is the most effective, although its bactericidal activity is similar to that of omeprazole. Pantoprazole is the least effective. The mechanisms that account for the antibacterial effects of PPIs may depend on a structural similarity of PPIs to antibiotics which are active against H. pylori, on the inhibition of bacterial urease exerted by PPIs, or on the possible interaction of PPIs with bacterial ATPases that regulate the transmembrane ion flux. Recent studies have shown that PPIs have anti-inflammatory actions and can interfere with the host-bacteria interactions. Lansoprazole can bind to polymorphonuclear leukocytes that infiltrate the gastric mucosa colonized by H. pylori and can thus inhibit the oxidative burst of activated inflammatory cells. In an in vivo study, lansoprazole reduced the degree of activity of histologic gastritis independently of the presence of H. pylori. In another study, omeprazole was capable of inhibiting the cytotoxic activity of NK T cells. Investigation of PPI interactions with H. pylori activities and the cellular immune response to the infection may help us to understand the pathogenic mechanisms of H. pylori-associated diseases and enable clinicians to better treat them.

Evaluation of a new ultrashort triple therapy for Helicobacter pylori disease

BACKGROUND

1-week proton pump inhibitor-based triple therapies are considered the most effective and convenient drug combinations for curing Helicobacter pylori infection. Short therapies, lasting less than 1 week have been investigated rarely.

AIM

To assess the efficacy and tolerability of a 3-day lansoprazole triple therapy after 1 day of lansoprazole pre-treatment.

METHODS

Seventy H. pylori-positive (rapid urease test and histology) patients received LAzT3 regimen (lanzoprazole 30 mg b.d. and azithromycin 500 mg o.m. for 3 days; tinidazole 2000 mg o.m. on day 1 and 1000 mg o.m. on days 2-3) after 1 day of lansoprazole pretreatment. Patients with active ulcer received lansoprazole 30 mg o.m. for an additional 4 weeks. Follow-up gastroscopy was carried out 4-6 weeks after completion of therapy. Eradication was defined as negative histology and rapid urease test.

RESULTS

Four patients failed to attend the follow-up endoscopy. One patient complained of minor side-effects. H. pylori was eradicated in 57 of 66 patients suitable for evaluation, with a per-protocol cure rate of 86.3% (95%CI: 76-94%), and an intention-to-treat cure rate of 81.4% (95%CI: 70-90%).

CONCLUSIONS

This new ultrashort triple therapy including lansoprazole, azithromycin and tinidazole seems to be effective in eradicating H. pylori. It is safe and well-tolerated, and may be taken into consideration as a valid alternative to the better known and widely used 1-week proton pump inhibitor-based triple therapies.

Proton pump inhibitors. Pharmacology and rationale for use in gastrointestinal disorders

Proton pump inhibitors (PPIs) are drugs which irreversibly inhibit proton pump (H+/K+ ATPase) function and are the most potent gastric acid-suppressing agents in clinical use. There is now a substantial body of evidence showing improved efficacy of PPIs over the histamine H2 receptor antagonists and other drugs in acid-related disorders. Omeprazole 20 mg/day, lansoprazole 30 mg/day, pantoprazole 40 mg/day or rabeprazole 20 mg/day for 2 to 4 weeks are more effective than standard doses of H2-receptor antagonists in healing duodenal and gastric ulcers. Patients with gastric ulcers should receive standard doses of PPIs as for duodenal ulcers but for a longer time period (4 to 8 weeks). There is no conclusive evidence to support the use of a particular PPI over another for either duodenal or gastric ulcer healing. For Helicobacter pylori-positive duodenal ulceration, a combination of a PPI and 2 antibacterials will eradicate H. pylori in over 90% of cases and significantly reduce ulcer recurrence. Patients with H. pylori-positive gastric ulcers should be managed similarly. PPIs also have efficacy advantages over ranitidine and misoprostol and are better tolerated than misoprostol in patients taking nonsteroidal anti-inflammatory drugs (NSAIDs). In endoscopically proven gastro-oesophageal reflux disease, standard daily doses of the PPIs are more effective than H2-receptor antagonists for healing, and patients should receive a 4 to 8 week course of treatment. For severe reflux, with ulceration and/or stricture formation, a higher dose regimen (omeprazole 40 mg, lansoprazole 60 mg, pantoprazole 80 mg or rabeprazole 40 mg daily) appears to yield better healing rates. There is little evidence that PPIs lead to resolution of Barrett's oesophagus or a reduction of subsequent adenocarcinoma development, but PPIs are indicated in healing of any associated ulceration. In Zollinger-Ellison syndrome, PPIs have become the treatment of choice for the management of gastric acid hypersecretion.

Comparison of omeprazole and lansoprazole in short-term triple therapy for Helicobacter pylori infection

BACKGROUND

Effective anti-Helicobacter pylori therapies with few side-effects are needed.

AIM

To study the effectiveness of short-term triple therapy with amoxycillin, clarithromycin and either omeprazole or lansoprazole for eradication and healing of peptic ulcers.

METHODS

Patients with gastric or duodenal ulcers received amoxycillin (1 g b.d.), clarithromycin (500 mg b.d.) and lansoprazole (30 mg b.d.) (LAC) or omeprazole (20 mg b.d.) (OAC) for 7 days. Endoscopic examinations were performed before treatment and at least 4 weeks after completion of therapy. H. pylori status was confirmed by rapid urease test and histological examination (Giemsa stain) from gastric biopsies taken from both the antrum and the body.

RESULTS

A total of 356 patients were randomized in this single-blind study. On a per protocol basis, H. pylori was eradicated in 134 of 170 patients (79%) in the lansoprazole group and in 105 of 146 (72%) in the omeprazole group (P = 0.189); and in intention-to-treat analysis 72% and 62%, respectively (P = 0.043). Healing of the ulcers was obtained in 166 of 186 (98%), and in 139 of 146 patients (95%), respectively (P = 0.357). Side-effects occurred in two patients in the LAC group and in six in the OAC group B (four stopped therapy).

CONCLUSIONS

This study has shown that the two regimens are highly effective in healing duodenal ulcers and are well tolerated. Neither treatment achieves the ideal cure rate for H. pylori. Lansoprazole does not appear to have a significant advantage over omeprazole either in ulcer healing or in H. pylori eradication.

Antimicrobial activity of novel furanonaphthoquinone analogs

Analogs of furanonaphthoquinone (FNQ) from Tecoma ipe Mart had MICs ranging from 1.56 to 25 microg/ml against gram-positive bacteria. FNQ showed significantly lower MICs against methicillin-resistant Staphylococcus aureus than against methicillin-sensitive S. aureus. FNQ inhibited Helicobacter pylori with an MIC of 0.1 microg/ml. Fungi, including pathogenic species, were sensitive to FNQ with MICs similar to those of amphotericin B.

Combination treatment with ranitidine is highly efficient against Helicobacter pylori despite negative impact of macrolide resistance

BACKGROUND

This double-blind, randomized study evaluated the efficacy of dual and triple therapies including ranitidine for treatment of Helicobacter pylori infection.

MATERIALS AND METHODS

Dyspeptic patients (n = 105) with a positive rapid urease test formed the intention-to-treat population (ITT). All patients were assigned to 14 days treatment with ranitidine 300 mg b.i.d and clarithromycin 750 mg b.i.d. Group A (n = 53) also received a placebo twice daily, while group B (n = 52) received lymecycline 300 mg b.i.d. Treatment with ranitidine, 150 mg b.i.d, was continued for an additional 30 days. H. pylori infection was verified by culture. Twelve weeks after antibiotic treatment, H. pylori status was investigated by culture and 14C-urea breath test (UBT). The per-protocol (PP) group consisted of 73 patients (A, n = 38; B, n = 35).

RESULTS

Cure rates were 87% (95% C.I. = 72% to 94%) vs. 72% (95% C.I. = 58% to 83%) in the ITT-group and 89% (95% C.I. = 73% to 97%) vs. 87% (95% C.I. = 72% to 96%) in the PP-population (culture and UBT) when triple and dual therapies were compared. In all patients who were not cured, clarithromycin resistance of H. pylori was acquired. Side effects were experienced by 54% of patients.

CONCLUSIONS

The difference in efficacy between the two treatment regimens was not significant. However, the cure rates in this study are comparable to combination treatments with omeprazole. Treatment failures were due to acquired clarithromycin resistance.

Basis for the selective antibacterial activity in vitro of proton pump inhibitors against Helicobacter spp

Proton pump inhibitors of the benzimidazole type exert a specific antibacterial activity against Helicobacter pylori in vitro. In the present study, the basis for this selectivity was investigated, and in particular, various factors affecting the in vitro antibacterial activity of sulfide analogs of benzimidazoles were studied. Upon preincubation of omeprazole for a period of up to 72 h in a buffer at pH 7, a product was formed that was bactericidal for H. pylori but had no effect on urease activity. Sulfide constitutes the main end product of degradation. The sulfide analog of omeprazole (H 168/22) exerted a bactericidal activity specifically against both resting (in buffer) and growing (in broth) Helicobacter spp., and time-kill in buffer at pH 5 was enhanced compared to that at pH 7. There was no or very low covalent binding of 3H-labeled H 168/22 to Helicobacter spp. or to other gram-negative and gram-positive bacteria. In the presence of fetal calf serum (FCS) under the same conditions, binding was only slightly lowered while the killing activity was markedly reduced, indicating a probably nonspecific interaction with proteins and/or protection of bacterial target(s) by FCS. Addition of H 168/22 (four times the minimum bactericidal concentration [MBC]) to exponentially growing H. pylori immediately stopped growth, and after an incubation period of 20 h viable counts were reduced by >7 log10. One-hour exposure of H. pylori to the drug followed by repeated washing retarded growth by about 2 h, indicating that the effect is reversible after short-term exposure. MICs and MBCs of various sulfide structures were lower than those obtained in broth after the addition of the corresponding sulfoxide. Thus, the MBC of the sulfide structure of omeprazole against 140 clinical isolates of H. pylori ranged from 8 to 32 microg/ml, compared to an MBC of omeprazole of 32 to 128 microg/ml. A similar potency was also recorded against other helicobacters. In conclusion, formation of sulfides of benzimidazoles in culture media is the reason for the selective antibacterial effect against H. pylori. The sulfides rapidly exerted a reversible antibacterial activity, which was specific against both resting and growing Helicobacter spp. without any covalent protein binding.

Urease-independent chemotactic responses of Helicobacter pylori to urea, urease inhibitors, and sodium bicarbonate

Helicobacter pylori CPY3401 and an isogenic urease-negative mutant, HPT73, showed chemotactic responses to urea, flurofamide (a potent urease inhibitor), and sodium bicarbonate. Since urea and sodium bicarbonate are secreted through the gastric epithelial surface and hydrolysis of urea by urease on the bacterial surface is essential for colonization, the chemotactic response of H. pylori may be crucial for its colonization and persistence in the stomach.

Urease-independent chemotactic responses of Helicobacter pylori to urea, urease inhibitors, and sodium bicarbonate

Helicobacter pylori CPY3401 and an isogenic urease-negative mutant, HPT73, showed chemotactic responses to urea, flurofamide (a potent urease inhibitor), and sodium bicarbonate. Since urea and sodium bicarbonate are secreted through the gastric epithelial surface and hydrolysis of urea by urease on the bacterial surface is essential for colonization, the chemotactic response of H. pylori may be crucial for its colonization and persistence in the stomach.

One-week therapy for Helicobacter pylori. A randomized trial of two treatment regimens

In clinical practice, eradication of Helicobacter pylori infection may be difficult due to medication side effects and the need for 2 weeks of therapy. Because therapies of shorter duration may improve patient compliance and reduce treatment side effects, we compared the efficacy and tolerability of two anti-H. pylori treatments of 1 week's duration. Patients with H. pylori infection were randomized to treatment with either (a) short-course triple therapy, composed-of bismuth subsalicylate (Pepto-Bismol, Procter & Gamble, Cincinnati, OH, U.S.A.) two tablets four times daily, amoxicillin 1 g (two 500-mg tablets) twice daily, and metronidazole 500 mg four times daily on days 5-7 or (b) omeprazole 40 mg twice a day with amoxicillin 1 g twice a day for 1 week. At least 4 weeks posttreatment, efficacy was evaluated with either histological evaluation of antral biopsies for H. pylori or 14C urea breath testing. Patients who failed initial therapy were allowed to cross over to the alternative treatment regimen after a minimum "wash-out" period of 5 weeks. Patients completed a diary during therapy to monitor both compliance and side effects. Thirty-four patients completed the study, 10 receiving both treatment regimens. Treatment with the shortcourse triple therapy eradicated H. pylori in 78.3% of treatments compared with 38% with the high-dose omeprazole/ amoxicillin combination (p < 0.05). Patients were highly compliant with both treatments, and mild side effects, such as transient loose stools or abdominal pain, were common in both groups. This is the first report from North America confirming the success of the short-course triple therapy for the eradication of H. pylori. The high-dose omeprazole/ amoxicillin regimen's eradication rate was markedly inferior to that achieved by the short-course triple therapy regimen and should not be used. Comparative studies of the short-course triple therapy regimen with other 7-day anti-H. pylori treatment regimen therapies are indicated.

Effectiveness of quadruple therapy using lansoprazole, instead of omeprazole, in curing Helicobacter pylori infection

BACKGROUND

Omeprazole enhances the efficacy of bismuth-based triple therapy. It is unknown whether the same is true for other proton pump inhibitors. Lansoprazole has superior anti-Helicobacter activity in vitro and possibly also in vivo; therefore we investigated quadruple therapy with lansoprazole.

MATERIALS AND METHODS

In two studies performed in separate hospitals, a total of 67 Helicobacter pylori-positive patients were treated with 7-day quadruple therapy (lansoprazole, colloidal bismuth subcitrate, tetracycline, and metronidazole) after 3 days of lansoprazole pretreatment. Testing for cure was done by endoscopy in study 1 and by breath test in study 2.

RESULTS

Cure rates per protocol were 31 of 31 (100%) in study 1 and 30 of 32 (94%) in study 2. Intention-to-treat cure rates were 31 of 35 (89%) in study 1 and 30 of 32 (94%) in study 2. Cured overall were 32 of 34 with a metronidazole sensitive strain and 3 of 3 with a metronidazole-resistant strain. Data on side effects were collected from 51 patients. Twelve (21%) had no side effects, 27 (53%) had mild side effects, 10 (20%) had moderate side effects, but only 2 (4%) had severe side effects. Side effects, never were the reason that a patient stopped taking the medication.

CONCLUSIONS

The results with lansoprazole-quadruple therapy are comparable to the historic control group treated with omeprazole-quadruple therapy. The cure rare is very high, and although mild to moderate side effects occurred in many patients, everybody finished the treatment regime.

Oxygen concentration influences proton pump inhibitor activity against Helicobacter pylori in vitro

Omeprazole and lansoprazole are proton pump inhibitors that have shown activity against Helicobacter pylori and other Helicobacter species when tested by agar dilution. Lansoprazole was more active against H. pylori than was omeprazole, and the activity was independent of urease production. Disk susceptibility tests and agar dilution MIC determinations were performed to investigate the effects of incubation under different sets of atmospheric conditions on H. pylori inhibition. Oxygen concentration was found to influence proton pump inhibitor activity in vitro, with higher concentrations leading to greater susceptibility. The method of testing is important in determining the anti-Helicobacter activity of proton pump inhibitors.