Efficacy and safety of three 7-day Helicobacter pylori eradication regimens containing ranitidine bismuth citrate

Tinidazole: a nitroimidazole antiprotozoal agent

BACKGROUND

Tinidazole, a structural analogue of metrondazole, is an antiprotozoal agent that has been widely used in Europe and developing countries for >2 decades with established efficacy and acceptable tolerability. It was recently approved by the US Food and Drug Administration for the treatment of trichomoniasis, giardiasis, amebiasis, and amebic liver abscess.

OBJECTIVE

This article reviews the pharmacologic and pharmacokinetic properties and clinical usefulness of tinidazole.

METHODS

Relevant information was identified through a search of MEDLINE (1966-August 2005), Iowa Drug Information Service (1966-August 2005), and International Pharmaceutical Abstracts (1970-August 2005) using the terms tinidazole, Fasigyn, and nitroimidazole.

RESULTS

In vitro, tinidazole exhibits activity against pathogenic protozoa (eg, Tricbomonas vaginalis, Entamoeba bistolytica, Giardia duodenalis), a wide range of clinically significant anaerobic bacteria (eg, Bacteroides fragilis, Clostridium difficile), and the microaerophilic bacterium Helicobacter pylori. In susceptible protozoal and bacterial cells, tinidazole is reduced to cytotoxic intermediates that covalently bind to DNA, causing irreversible damage. In human adults, tinidazole had a bioavailability of 100% and a V(d) of 50.7 L, was minimally bound to plasma protein (12%), had a plasma elimination t((1/2)) of 12.3 hours, and was eliminated primarily by hepatic metabolism (approximately 63%). Dose adjustment does not appear to be necessary on the basis of race, sex, or renal function. No data were found on the disposition of tinidazole in patients with hepatic insufficiency; therefore, use of tinidazole in patients with severe hepatic impairment (Child-Pugh class C) is not recommended. Clinical cure rates in patients with trichomoniasis, giardiasis, amebiasis, and amebic liver abscess were generally >90%. In comparative trials, tinidazole was as effective as metronidazole in the treatment of trichomoniasis and was significantly more effective than metronidazole in the treatment of giardiasis (P < 0.05) and amebiasis (P < 0.05). The most commonly reported (>1%) adverse effects included bitter taste, nausea, abdominal discomfort, anorexia, vomiting, and fatigue. The recommended dosage of tinidazole is a single dose of 2 g for trichomoniasis and giardiasis, and 2 g/d for 3 to 5 days for amebiasis.

CONCLUSIONS

Tinidazole appears to be a promising agent for the treatment of trichomoniasis, giardiasis, amebiasis, and amebic liver abscess. Clinical studies are needed to evaluate the use of tinidazole against anaerobic bacteria and H pylori.

Systematic review and meta-analysis: proton pump inhibitor vs. ranitidine bismuth citrate plus two antibiotics in Helicobacter pylori eradication

OBJECTIVE

To systematically review the Helicobacter pylori eradication efficacy with ranitidine bismuth citrate (RBC) and two antibiotics, and to conduct a meta-analysis of randomized clinical trials comparing the efficacy of proton pump inhibitor (PPI) vs. RBC with two antibiotics for 1 week.

SELECTION OF STUDIES

Studies evaluating RBC plus two antibiotics were considered. For the meta-analysis, randomized controlled trials comparing PPI vs. RBC plus two antibiotics for 1 week were included.

SEARCH STRATEGY

Electronic and manual bibliographical searches. Assessment of study quality and data extraction: Independently done by two reviewers.

DATA SYNTHESIS

'Intention-to-treat' eradication rate. Meta-analysis was performed, combining the odds ratios (OR) of the individual studies. Subanalysis: Depending on the type of antibiotics and the quality of the studies.

RESULTS

Mean H. pylori eradication with 7-day RBC-clarithromycin-amoxicillin, RBC-clarithromycin-nitroimidazole, and RBC-amoxicillin-nitroimidazole was 83%, 86%, and 71%, respectively. The meta-analysis showed comparable efficacy with RBC and PPI when they were combined with clarithromycin and amoxicillin (OR = 1.11; 95% CI = 0.88-1.40), or with amoxicillin and metronidazole (OR = 0.92; 95%CI = 0.60-1.41). However, when comparing PPI vs. RBC plus clarithromycin and a nitroimidazole, higher cure rates with RBC than with PPI were demonstrated (OR = 1.65; 95% CI = 1.15-2.37).

CONCLUSION

The efficacy of RBC and PPI-based triple regimens were comparable when using the clarithromycin-amoxicillin or the amoxicillin-metronidazole combination. However, RBC seems to have a higher efficacy than PPI when clarithromycin and a nitroimidazole are the antibiotics prescribed. Therefore, if one prefers to use the clarithromycin-nitroimidazole regimen, RBC should be used instead of a PPI.

Role of antibiotic sensitivity testing before first-line Helicobacter pylori eradication treatments

BACKGROUND

The resistance of Helicobacter pylori to antibiotics has been advocated as a major cause of treatment failure, and antimicrobial sensitivity testing has been proposed to improve efficacy; however, its role before first-line therapy has not been investigated in detail.

AIM

To assess whether antimicrobial sensitivity testing improves the eradication rate of first-line anti-Helicobacter treatments and to compare the effectiveness of ranitidine bismuth citrate and omeprazole in the presence of H. pylori resistance to antibiotics.

METHODS

Two hundred and forty-two patients were assigned to either empirical or antimicrobial sensitivity testing-based treatment; within each group, subjects were further randomized to receive ranitidine bismuth citrate, 400 mg b.d., tinidazole, 500 mg b.d., and clarithromycin, 500 mg b.d., or omeprazole, 20 mg b.d., clarithromycin, 500 mg b.d., and amoxicillin, 1 g b.d., for 1 week, with substitution of the resistant antibiotic in the antimicrobial sensitivity testing-based treatment group.

RESULTS

Eradication rates were 67% [confidence interval (CI), 55-79%] in the empirical treatment group and 76% (CI, 65-87%) in the antimicrobial sensitivity testing-based group (P=N.S.). The overall success rate was 60% (CI, 51-69%) with omeprazole and 82% (CI, 73-91%) with ranitidine bismuth citrate (P<0.03); the latter overcame antibiotic resistance in 12 of 15 strains vs. zero of eight strains by omeprazole.

CONCLUSIONS

Antimicrobial sensitivity testing before first-line treatment does not improve the eradication rate, which is greater when ranitidine bismuth citrate is included in the treatment.

A systematic comparison of triple therapies for treatment of Helicobacter pylori infection with proton pump inhibitor/ ranitidine bismuth citrate plus clarithromycin and either amoxicillin or a nitroimidazole

BACKGROUND

Triple therapies with proton pump inhibitor/ranitidine bismuth citrate (RBC), clarithromycin (C) and either amoxicillin (A) or a nitroimidazole (I) are widely accepted as treatment for Helicobacter pylori infection. However, it is not clear which of these antibiotic combinations should be preferred.

AIM

To evaluate whether there is a difference in efficacy between triple therapies with proton pump inhibitor/RBC, clarithromycin and either amoxicillin or a nitroimidazole.

METHODS

The literature was examined for randomized trials comparing proton pump inhibitor/RBC-C-A and proton pump inhibitor/RBC-C-I. Studies were grouped according to the type of acid inhibitor used (proton pump inhibitor or RBC) and differences between pooled cure rates were calculated.

RESULTS

Forty-seven studies were identified: seven using RBC, 39 using proton pump inhibitor, one using both. RBC-C-I was somewhat superior to RBC-C-A, although this difference only reached statistical significance in intention-to-treat analysis. Overall, proton pump inhibitor-C-I and proton pump inhibitor-C-A were equally effective, but in nitroimidazole-susceptible strains, proton pump inhibitor-C-I performed better, in nitroimidazole-resistant strains, proton pump inhibitor-C-A performed better. No serious side-effects were reported and pooled drop-out rates were equal.

CONCLUSIONS

In general, proton pump inhibitor-C-I and proton pump inhibitor-C-A are equally effective and therefore other factors such as local prevalence of resistant strains, cost of therapy and options for second-line treatment should determine which regimen should be preferred. When using RBC, the RBC-C-I combination is somewhat superior to RBC-C-A.

Helicobacter pylori infection--current treatment practice

Helicobacter pylori infection, which is present in 30 - 60% of the population in developed countries and in more than 60% in developing countries, is established to be a major cause of gastritis, peptic ulcer disease and gastric cancer. Eradication therapy has been incorporated into clinical practice over the past 15 years. Treatment regimens include a 2 week bismuth-based triple therapy (a bismuth compound plus metronidazole, tetracycline or amoxycillin), a 1 week proton-pump inhibitor (PPI)-based triple therapy and a 1 week ranitidine bismuth citrate (RBC)-based triple therapy (a PPI or RBC plus any two of the three antibiotics, metronidazole, amoxycillin and clarithromycin). These regimens achieve eradication rates of >> 80%. H. pylori resistance to metronidazole and clarithromycin decreases the clinical efficacy of most regimens, despite the high eradication rates for resistant strains achieved by the RBC-triple therapy in some recent trials. The dose of antibiotics (especially clarithromycin) and the duration of treatment may also influence the eradication rate. Doctors' beliefs impact on clinical practice and, thus, influence the clinical application of eradication therapy. Whereas peptic ulcer disease and primary gastric low-grade B-cell mucosa-associated lymphoid tissue lymphoma (MALToma) have become established as definite indications for eradication therapy, there remain controversies surrounding non-ulcer dyspepsia, gastro-oesophageal reflux disease, atrophic gastritis, intestinal metaplasia, use of non-steroidal anti-inflammatory drugs (NSAIDs) and H. pylori-related extradigestive diseases.

The influence of metronidazole resistance on the efficacy of ranitidine bismuth citrate triple therapy regimens for Helicobacter pylori infection

AIM

To assess the influence of metronidazole resistance on the efficacy of ranitidine bismuth citrate-based triple therapy regimens in two consecutive studies.

METHODS

In the first study, patients with a culture-proven Helicobacter pylori infection were treated with ranitidine bismuth citrate 400 mg, metronidazole 500 mg, and clarithromycin 500 mg, all twice daily for 1 week (RMC). In the second study, amoxycillin 1000 mg was substituted for clarithromycin (RMA). Susceptibility testing for metronidazole was performed with the E-test. Follow-up endoscopy was performed after >/= 4 weeks. Antral biopsy samples were taken for histology and urease test, and culture and corpus samples for histology and culture.

RESULTS

112 patients, 53 males, age 55 +/- 14 years (39 duodenal ulcer, 7 gastric ulcer and 66 gastritis) were treated with RMC, and 89 patients, 52 males, age 58 +/- 15 years (23 duodenal ulcer, 7 gastric ulcer and 59 gastritis) were treated with RMA. For RMC, intention-to-treat eradication results were 98% (59/60, 95% CI: 91-100%) and 95% (20/21, 95% CI: 76-100%) for metronidazole susceptible and resistant strains, respectively (P = 0.45). For RMA these figures were 87% (53/61, 95% CI: 76-94%) for metronidazole susceptible strains and 22% (2/9, 95% CI: 3-60%) for resistant strains (P = 0.0001).

CONCLUSION

Both regimens are effective in metronidazole susceptible strains. However, in contrast to the amoxycillin-containing regimen, that containing clarithromycin is also effective in resistant strains.

Optimal duration of therapy combining ranitidine bismuth citrate with clarithromycin and metronidazole in the eradication of Helicobacter pylori infection

BACKGROUND

Ranitidine bismuth citrate (RBC) co-prescribed with clarithromycin and metronidazole for 1 week has been shown to be an effective eradicating regimen for Helicobacter pylori.

AIM

To determine the optimal duration of this regimen.

METHODS

A series of 165 dyspeptic patients were recruited for this randomized, open, parallel-group study. They were subdivided into three groups receiving RBC 400 mg b.d. plus clarithromycin 250 mg b.d. and metronidazole 500 mg b.d. for three different periods (4, 7 and 10 days). H. pylori infection was assessed by the concomitant positivity of CLO-test and histology performed at the pre-entry endoscopy. The bacterium was considered eradicated on the basis of a negative 13C-urea breath test performed at least 28 days after the completion of treatment.

RESULTS

The three subgroups were well matched and 16 patients dropped out of the study for many reasons (six in the 4-day, five in the 7-day and five in the 10-day treatment regimens). Intention-to-treat cure rates were 60%, 84% and 85%, and the per-protocol rates 67%, 92% and 94% in the 4-day, 7-day and 10-day treatment regimens, respectively. There was a significant difference, P = 0.003-0.006 on intention-to-treat and P = 0.001-0. 002 on per protocol analysis between the 4-day and the 7-day and the 4-day and the 10-day periods, respectively. The 7-day and 10-day periods did not differ from each other. Side-effects were reported in 9%, 14% and 20% of the 4-, 7- and 10-day regimens. They led to stopping treatment in four cases (one in the 7-day and three in the 10-day period). There was no statistical difference among them.

CONCLUSIONS

Reducing the duration of RBC-based triple therapy to 4 days provides a low and unacceptable rate of H. pylori eradication. As there is no difference between 7 and 10 days of treatment, 1 week represents the optimal time period for this kind of treatment, based on RBC plus two antibiotics.

Review article: one-week clarithromycin triple therapy regimens for eradication of Helicobacter pylori

BACKGROUND

One-week triple therapies have been endorsed as the treatment regimens of choice for eradication of Helicobacter pylori infection. Those that include clarithromycin appear to be the most effective.

AIM

To review reports of triple therapies that include clarithromycin.

METHODS

Reports were identified from the literature to May 1998. The variation between study designs prevents a formal meta-analysis. A measure of the relative efficacies of regimens has, however, been gained by comparison and by pooling of intention-to-treat eradication rates.

RESULTS

One hundred and ninety-two studies were identified which included 264 treatment arms of a 1-week triple therapy composed of clarithromycin with amoxycillin or a nitroimidazole (metronidazole or tinidazole), and either ranitidine bismuth citrate or a proton pump inhibitor (omeprazole, lansoprazole or pantoprazole). From reports of these studies, an intention-to-treat H. pylori eradication rate could be determined from 210 treatment arms of 151 studies.

CONCLUSIONS

There is little to choose between the efficacies of 1-week clarithromycin-based triple therapy eradication regimens. However, those comprising clarithromycin, a nitroimidazole and either ranitidine bismuth citrate or a high dose of omeprazole are, in general, the most effective. Against antibiotic-resistant strains of H. pylori, regimens including ranitidine bismuth citrate may be more effective than those including a proton pump inhibitor.