Influence of Helicobacter pylori eradication therapy on 13C aminopyrine breath test: comparison among omeprazole-, lansoprazole-, or pantoprazole-containing regimens

Appropriateness of proton pump inhibitors treatment in clinical practice: Prospective evaluation in outpatients and perspective assessment of drug optimisation

BACKGROUND

High rates of inappropriate proton pump inhibitor (PPI) prescriptions have been reported in retrospective database analyses. Assessing the appropriateness of long-term PPIs in outpatients, with a proactive approach at drug optimisation may enhance treatment adequacy.

AIMS

To describe the characteristics of outpatients who are on long-term PPIs, to assess the magnitude of inappropriate PPI prescriptions, and to evaluate the rate of drug optimisation following specialist recommendations.

METHODS

Appropriateness of long-term (>8weeks) PPI prescription was prospectively assessed in 249 consecutive patients referred to a Gastroenterology outpatient clinic. We recorded reason for prescription, dose, modality, duration of therapy, and attempts at PPI optimisation.

RESULTS

PPIs were inappropriately prescribed in 96/249 patients (38.6%). Gastro-oesophageal reflux disease (50/143, 35.0%) and prophylaxis of anti-platelet/non-steroidal anti-inflammatory drugs (5/49, 10.2%) were the most common PPI indications and those with the lowest rate of inappropriateness, while the highest rates were observed for treatment of dyspepsia (10/12, 83.3%) and anti-coagulant therapy (21/21, 100%). PPI treatment was optimised in 112 patients (45.0%).

CONCLUSIONS

PPIs are inappropriately used in about 40% of outpatients, reflecting scant attention to guidelines. A proactive approach may improve therapeutic adequacy in approximately half of patients. Educational efforts to guide PPI prescription should be further pursued.

Role of the 13C-methacetin breath test in the assessment of acute liver injury in a rat model

AIM: To evaluate the role of the ¹³C-methacetin breath test (¹³C-MBT) in the assessment of acute liver injury in a rat model.

METHODS: Acute liver injury in rats was induced by a single intraperitoneal injection of D-galactosamine (D-GalN). Forty-eight male Sprague-Dawley rats were randomly assigned to a control group (n = 8) and five model groups (each n = 8), and acute liver injury was assessed at different time points (6, 12, 24, 48 and 72 h) after D-GalN injection. The ¹³C-MBT, biochemical tests, 15-min retention rate of indocyanine green (ICG_R15), and liver biopsy were performed and compared between the control and model groups. Correlations between parameters of the ¹³C-MBT (T_max, MV_max, CUM₁₂₀ and DOB_max), biochemical tests, ICG_R15 and liver necrosis score were also analyzed using Spearman’s correlation analysis.

RESULTS: T_max, MV_max, CUM₁₂₀ and DOB_max, as well as most of the traditional methods, correlated with the liver necrosis score (r = 0.493, P < 0.05; r = -0.731, P < 0.01; r = -0.618, P < 0.01; r = -0.592, P < 0.01, respectively). MV_max, CUM₁₂₀ and DOB_max rapidly decreased and were lower than those in the controls as early as 6 h after D-GalN injection (3.84 ± 0.84 vs 5.06 ± 0.78, P < 0.01; 3.35 ± 0.72 vs 4.21 ± 1.44, P < 0.05; 52.3 ± 20.58 vs 75.1 ± 9.57, P < 0.05, respectively) and reached the lowest point 24 h after D-GalN injection. MV_max, CUM₁₂₀ and DOB_max returned to normal levels 72 h after D-GalN injection and preceded most of the traditional methods, including liver biopsy.

CONCLUSION: The ¹³C-MBT is a sensitive tool for the timely detection of acute liver injury and early prediction of recovery in a rat model. Further clinical studies are warranted to validate its role in patients with acute liver injury.

Influence of different proton pump inhibitors on activity of cytochrome P450 assessed by [(13)C]-aminopyrine breath test

Aminopyrine is metabolized by cytochrome P450 (CYP) in the liver. The investigators evaluated influences of different PPIs on CYP activity as assessed by the [(13)C]-aminopyrine breath test ([(13)C]-ABT). Subjects were 15 healthy volunteers with different CYP2C19 status (5 rapid metabolizers [RMs], 5 intermediate metabolizers [IMs], and 5 poor metabolizers [PMs]). Breath samples were collected before and every 15 to 30 minutes for 3 hours after oral ingestion of [(13)C]-aminopyrine 100 mg on day 8 of each of the following regimens: control; omeprazole 20 mg and 80 mg, lansoprazole 30 mg, and rabeprazole 20 mg. Changes in carbon isotope ratios in carbon dioxide ((13)CO(2)/(12)CO(2)) in breath samples were measured by infrared spectrometry and expressed as delta-over-baseline (DOB) ratios (‰). Mean areas under the curve of DOB from 0 to 3 h (AUC(0-3h) of DOB) were significantly decreased by omeprazole 20 mg and lansoprazole 30 mg but not by rabeprazole 20 mg. Conversely, higher PPI dose (ie, omeprazole 80 mg) seemed to further decrease AUC(0-3h) of DOB in RMs but increased it in PMs. Omeprazole and lansoprazole at the standard doses inhibit CYP activity but rabeprazole does not, whereas high-dose omeprazole seems to induce CYPs.

Methods and functions: Breath tests

Breath tests provide a valuable non-invasive diagnostic strategy to in vivo assess a variety of enzyme activities, organ functions or transport processes. Both the hydrogen breath tests and the (13)C-breath tests using the stable isotope (13)C as tracer are non-radioactive and safe, also in children and pregnancy. Hydrogen breath tests are widely used in clinical practice to explore gastrointestinal disorders. They are applied for diagnosing carbohydrate malassimilation, small intestinal bacterial overgrowth and for measuring the orocecal transit time. (13)C-breath tests non-invasively monitor the metabolisation of a (13)C-labelled substrate. Depending on the choice of the substrate they enable the assessment of gastric bacterial Helicobacter pylori infection, gastric emptying, liver and pancreatic function as well as measurements of many other enzyme activities. The knowledge of potential pitfalls and influencing factors are important for correct interpretation of breath test results before drawing clinical conclusions.

Monitoring cytochrome P-450 activity during rabeprazole treatment in patients with gastresophageal reflux disease

Proton pump inhibitors (PPIs) are the cornerstone in the treatment of gastresophageal reflux disease (GORD). PPIs are metabolized by the hepatic cytochrome P-450 enzymes (CYP-450). Rabeprazole is a PPI whose metabolism shows fewer interactions compared to other PPIs. In this study we evaluated the influence of rabeprazole administration on hepatic CYP-450 activity as measured by the (13)C-aminopyrine breath test ((13)C-ABT) in a group of patients with GORD. (13)C-ABT was performed on five GORD patients both before and after 1 week of rabeprazole administration (20 mg, b.i.d.). Pretreatment (13)C-ABT results were compared to posttreatment results. Pre- and posttreatment (13)C-ABT results for patients were compared to those obtained in five controls who did the test twice, with a 1-week interval in between. Before treatment, the (13)C-ABT results for the GORD patients did not significantly differ from those of healthy subjects. After treatment, we observed no significant modification of the (13)C-ABT in GORD patients compared to pretreatment values ((13)C-ABT %dose/hr, 10.56+/-1.31 versus 11.17+/-0.88; (13)C-ABT %cumulative dose, 8.08+/-1.11 versus 8.34+/-0.56). Posttreatment (13)C-ABT results were not significantly different from those obtained in controls at weekly repetition of the test. In patients with GORD, 1-week, full-dose rabeprazole does not display any significant interactions with CYP-450 activity.

Can Helicobacter pylori eradication regimens be shortened in clinical practice? An open-label, randomized, pilot study of 4 and 7-day triple therapy with rabeprazole, high-dose levofloxacin, and tinidazole

BACKGROUND

Rabeprazole is a proton pump inhibitor which is particularly suitable for use in short-term Helicobacter pylori eradication treatment. Levofloxacin-based H. pylori eradication regimens have shown good efficacy and very few side effects. Shorter treatment and absence of significant side effects should improve compliance to therapy and increase the Hp H. pylori eradication rate.

AIMS

To evaluate the effectiveness of 2 rabeprazole-based H. pylori eradication regimens in an open-label, randomized study carried out in a clinical practice setting.

METHODS

One hundred sixty-nine consecutive, treatment-naive patients with H. pylori infection were randomized to receive rabeprazole (20 mg, bid), levofloxacin (500 mg, bid), and tinidazole (500 mg, bid) for either 4 [4-d rabeprazole, levofloxacin, tinidazole (RLT), n=85] or 7 days (7-d RLT, n=84). Before treatment, all patients underwent upper digestive endoscopy. Cure rates were assessed by means of C-urea breath test. and were compared with the eradication rate obtained with standard triple therapy in our Unit (ie, 78%) and average eradication rate reported in the literature (ie, 79%).

RESULTS

The intention-to-treat eradication rates were 94% [87% to 98%, 95% confidence interval (CI)] and 95% (88% to 99%, 95% CI) in the 4-day RLT and 7-day RLT regimens, respectively, whereas per-protocol eradication rates were 95% (88% to 99%, 95% CI) in the 4-day RLT and 96% (90% to 99%, 95% CI) in the 7-day RLT. Both treatment regimens obtained significantly higher eradication rates as compared with standard triple therapy. The 4-day RLT showed significantly fewer side effects.

CONCLUSIONS

In a clinical practice setting, both 4-day and 7-day rabeprazole, high-dose levofloxacin, tinidazole-based regimens achieved relevant H. pylori eradication rates in treatment-naive patients. The lower number of side effects makes the shorter treatment regimen preferable over the conventional 7-day treatment.

[Breath tests in the diagnosis of gastrointestinal diseases]

Determination of carbon or hydrogen markers in breath has allowed closer investigation of the pathogenic mechanisms of several gastrointestinal diseases. Thus, the 13C-urea breath test is a nonaggressive, simple and safe test with excellent accuracy both in the initial diagnosis of Helicobacter pylori infection and in confirmation of its eradication following treatment. Moreover, because of the simplicity, reproducibility and safety of these types of procedure, they have tended to substitute more uncomfortable and expensive techniques that were traditionally used in gastroenterology. Several breath tests have been developed that allow reliable evaluation of liver or exocrine pancreatic function, gastrointestinal motility, as related to gastric emptying or orocecal transit time, and a diagnostic approach to clinical problems that could be due to bacterial overgrowth or malabsorption of various sugars.

Influence of 1-week Helicobacter pylori eradication therapy with rabeprazole, clarithromycin, and metronidazole on 13C-aminopyrine breath test

Helicobacter pylori eradication therapy is commonly prescribed in the general population. Treatment consists of drugs that are mainly metabolized by the liver cytochrome P-450 (CYP) enzymatic pool. Most H. pylori-infected patients often take drugs for comorbid illnesses, therefore increasing the potential for drug-drug interactions. We aimed to evaluate the interactions of rabeprazole, clarithromycin, and metronidazole 1-week H. pylori eradication therapy with CYP-dependent liver metabolic function in clinical practice. Ten patients referred to our unit for H. pylori infection underwent 1-week eradication therapy with rabeprazole (20 mg, b.i.d.), clarithromycin (500 mg, b.i.d.), and metronidazole (500 mg, b.i.d.). We chose the 13C-aminopyrine breath test (13C-ABT) to evaluate CYP-dependent liver function since it is noninvasive and nonharmful. All patients underwent 13C-ABT at three time points: before therapy (to), at the end of therapy (t8), and after 1 month of follow-up (t38). Mean 13C-ABT dose/hr (t0 = 14.0 +/- 5.4, t8 = 13.5 +/- 4.0, t38 = 16.1 +/- 5.6) as well as 13C-ABT cumulative dose (t0 = 2.4 +/- 1.1, t8 = 2.4 +/- 0.8, t38 = 2.6 +/- 1.0) were not statistically different at the three time points of the study. These results did not seem to be influenced by drugs being administered concomitantly. In everyday clinical practice rabeprazole-based H. pylori eradication therapy does not seem to display any significant interactions with CYP-dependent liver function, even in patients on multiple drugs.

Inducibility of microsomal liver function may differentiate cirrhotic patients with maintained compared with severely compromised liver reserve

BACKGROUND AND AIM

Quantitative tests of liver function (QTLF) can be modulated by enzyme-inducing agents. The objective of the study was to examine changes in QTLF after treatment with Phenobarbital, a potent cytochrome P450-inducing agent.

METHODS

Forty-six consecutive patients with liver cirrhosis Child-Pugh score B and C (34 alcoholic, 12 hepatitis C) and a compromised aminopyrine breath test (ABT) were included. Thirty-six patients (group I) received phenobarbitone (150 mg) for 7 days. Ten patients (group II) received a placebo. The QTLF, which included ABT (microsomal liver function), galactose elimination capacity (GEC, cytosolic liver function), sorbitol clearance (SCl, liver plasma flow) and indocyanine green clearance (ICG, liver perfusion) was carried out before and after pharmacological induction.

RESULTS

Group I showed a basal ABT of 0.18 +/- 0.11% dose.kg/mmol CO2 (normal >0.6%), which increased significantly after induction (172%, P < 0.05), whereas in group II the ABT values did not change. In group IB, a subgroup of group I which exceeded the basal threshold value of 0.30% after stimulation (n = 22), the ABT values increased significantly to 0.44 +/- 0.17% (244%, P < 0.01). The GEC, SCl and ICG remained unchanged before and after induction.

CONCLUSIONS

After pharmacological induction, microsomal liver function increased significantly in a subgroup of patients with liver cirrhosis, whereas the GEC, SCl and ICG remained unchanged. Inducibility of the microsomal liver function could be used as a novel parameter of functional hepatic reserve and prognosis in cirrhosis.

Serum thrombopoietin levels are linked to liver function in untreated patients with hepatitis C virus-related chronic hepatitis

BACKGROUND

Thrombocytopenia can be found in patients with chronic hepatitis related to hepatitis C virus (HCV). Both hypersplenism and decreased liver production of thrombopoietin (TPO) have been hypothesized as mechanisms responsible for thrombocytopenia.

AIMS

To assess the presence of relationships among platelet count, spleen size, TPO serum levels, liver histology, and liver function in a group of patients with HCV-related chronic hepatitis.

METHODS

Platelet count, TPO serum levels, and spleen size were assessed in 25 untreated HCV positive chronic hepatitis patients undergoing liver biopsy. These parameters were correlated to liver histology and liver function as evaluated by means of [(13)C]aminopyrine breath test (ABT).

RESULTS

Both platelet counts (146 +/- 48 vs. 202 +/- 56 x 10(9)/1, P < 0.03) and TPO serum levels (103 +/- 24 vs. 158 +/- 7 1 pg/ml, P < 0.02) were lower among patients with high fibrosis scores as compared to patients with low fibrosis scores. Patients with thrombocytopenia as well as patients with high fibrosis scores had lower ABT results as compared to patients with normal platelet counts and patients with no or mild fibrosis, respectively. TPO serum levels were correlated to platelet count (r(s) = 0.493, P = 0.016), and negatively correlated to fibrosis stage (r(s) = -0.545, P = 0.008). Lastly, low TPO serum levels were associated to a decrease in liver function.

CONCLUSIONS

Our study showed that in patients with chronic hepatitis related to HCV infection serum TPO levels are correlated to liver functional impairment and to the degree of liver fibrosis.

13C-aminopyrine breath test to evaluate severity of disease in patients with chronic hepatitis C virus infection

BACKGROUND

There are few data on the use of the 13C-aminopyrine breath test to evaluate the severity of disease in patients with hepatitis C virus-related chronic liver disease, although these patients represent one of the most important problems in clinical hepatology.

AIMS

To compare 13C-aminopyrine breath test results of patients with hepatitis C virus-related chronic hepatitis and Child-Pugh class A cirrhosis with those of normal subjects, and to evaluate different methods of expressing 13C-aminopyrine breath test results.

METHODS

Twenty-four patients with hepatitis C virus-related chronic hepatitis and 17 patients with Child-Pugh class A cirrhosis underwent 13C-aminopyrine breath test. Breath samples were collected every 30 min up to 2 h after 13C-aminopyrine administration. 13C-Aminopyrine breath test results were expressed as a percentage of the administered dose of 13C recovered per hour (% dose/h) and the cumulative percentage of administered dose of 13C recovered over time (% dose cum). Nineteen healthy subjects served as controls. Patients with hepatitis C virus-related chronic hepatitis were divided into subgroups on the basis of histological staging and grading.

RESULTS

The 13C-aminopyrine breath test result (% dose/h) at 30 min was significantly different among the three subgroups of subjects (normal subjects, 11.5 +/- 3.5; chronic hepatitis patients, 8.1 +/- 4.1; cirrhosis patients, 5.0 +/- 3.1; P < 0.0005). Moreover, the differences between chronic hepatitis and cirrhosis patients were statistically significant (P < 0.03). The fibrosis score showed a significant inverse correlation with the 13C-aminopyrine breath test result (% dose/h) at 30 min (rs=- 0.409, P=0.05). The 13C-aminopyrine breath test result (% dose/h) at 30 min also allowed normal subjects and chronic hepatitis patients with low (< or = 2) or high (> 2) fibrosis scores to be distinguished. The 13C-aminopyrine breath test results (% dose cum) at 30, 60 and 90 min allowed discrimination between normal subjects and chronic hepatitis and cirrhosis patients. The 13C-aminopyrine breath test result (% dose cum) was also able to distinguish between normal subjects and chronic hepatitis patients with high but not low fibrosis scores. Both 13C-aminopyrine breath test results (% dose/h and % dose cum) at 120 min allowed the differentiation between normal subjects and chronic hepatitis patients with high (> or = 6) necro-inflammatory activity.

CONCLUSIONS

In patients with hepatitis C virus-related chronic liver disease, the 13C-aminopyrine breath test proved to be safe and easy to perform, and was able to evaluate different degrees of liver function impairment which were partly correlated to clinical and histological evaluation. In future studies, 13C-aminopyrine breath test results should be expressed in a standardized fashion to permit comparison.

Impairment of cytochrome P-450-dependent liver activity in cirrhotic patients with Helicobacter pylori infection

BACKGROUND

Helicobacter pylori gastric infection has been associated with various digestive and extra-digestive diseases. The systemic influence of gastric H. pylori infection seems to be mediated by the release of various cytokines. In liver disease, bacterial infections have been associated with the impairment of liver metabolic function.

AIMS

To evaluate the influence of H. pylori infection on liver function as assessed by means of the monoethylglycinexylidide test, which depends upon liver blood flow and cytochrome P-450 activity, and the 13C-galactose breath test, which depends on cytosolic enzymatic activity and is correlated with hepatic functional mass. Moreover, to evaluate whether H. pylori-associated modifications of liver function may be related to tumour necrosis factor-alpha serum levels.

PATIENTS AND METHODS

Thirty-five patients with liver cirrhosis of various aetiologies, who underwent monoethylglycinexylidide and 13C-galactose breath tests, were retrospectively evaluated for H. pylori infection by means of anti-H. pylori immunoglobulin G. The main clinical, biochemical and functional characteristics of the patients as well as their tumour necrosis factor-alpha serum levels were then analysed on the basis of the presence of H. pylori infection.

RESULTS

Twenty-one patients tested positive for H. pylori infection (60%), and 11 tested negative (31.4%). No clinical or biochemical differences were observed between H. pylori-infected and non-infected patients. H. pylori infection showed no difference in distribution according to Child-Pugh classes (A, 55%; B and C, 67%). The monoethylglycinexylidide test results were significantly lower at each sampling time in H. pylori-positive patients compared to H. pylori-negative patients (MEGX15, P=0.027; MEGX30, P=0.014; MEGX60, P=0.028), while 13C-galactose breath test showed no significant differences considering both cumulative percentage dose and percentage dose/h. The median tumour necrosis factor-alpha serum levels were no different between H. pylori-positive (16.1 pg/mL, 95% confidence interval, 8.7-28.7) and H. pylori-negative (12.3 pg/mL, 95% confidence interval, 8.7-23.4) patients.

CONCLUSIONS

In cirrhotic patients, H. pylori infection seems to selectively affect cytochrome P-450 liver activity, while hepatic functional mass does not seem to be impaired. Tumour necrosis factor-alpha does not seem to be the mediator of this impairment. Further studies are needed to evaluate the impact of H. pylori eradication on parameters of liver function.

Predictors of failure of Helicobacter pylori eradication with the standard 'Maastricht triple therapy'

BACKGROUND

Triple therapy with proton pump inhibitor, clarithromycin and amoxicillin has recently been proposed in Maastricht as first-line treatment for H. pylori infection.

AIM

To determine predictors of unsuccessful eradication.

METHODS

Two hundred and forty-eight patients underwent endoscopy with biopsies for rapid urease test, histology and culture with antibiotic susceptibility tests, and 13C-UBT. All infected patients were given pantoprazole (40 mg b.d.), clarithromycin (500 mg b.d.) and amoxicillin (1 g b.d.) for 1 week. Eradication was assessed by UBT at 4-6 weeks after therapy.

RESULTS

One hundred and sixty-two of 248 patients (65%) were infected. Culture was positive in 144 (89%). Prevalence rates of metronidazole, clarithromycin and amoxicillin resistance were 14, 8 and 3%, respectively. Eradication rates (95% CI) were 63% (54.7-70.6) by intention-to-treat analysis and 67% (59.4-75.4) by per protocol analysis. Drug compliance was excellent and side-effects were mild. Age > or = 45 years (OR: 2.35, CI: 1.30-4.25), smoking (OR: 1.37, CI 1.01-1.87) and high pre-treatment UBT results (OR: 1.36, CI: 1.08-1.72) were independent predictors of eradication failure. Gender, endoscopic findings, alcohol intake, and clarithromycin and amoxicillin resistance did not predict treatment failure.

CONCLUSION

Despite the low prevalence of primary antibiotic resistance in our geographical area, triple therapy with pantoprazole, amoxicillin and clarithromycin achieves low eradication rates. Smoking, age and pre-treatment UBT results are predictors of potential eradication failure.