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Introduction: Some investigators have suggested that the H. pylori infective status can be determined from a single 30-min post-dose breath sample of the [sup 13]C-urea breath test ([sup 13]C-UBT). The aim of this study was to evaluate the clinical importance of baseline measurement in [sup 13]C-UBT. Methods: Totally, 663 adults (age 20-80) with dyspepsia and 1052 children (age 6-14) in an epidemiological investigation were enrolled. The [sup 13]C-UBT was performed according to our standard protocol in which baseline breath sample was collected after 8 hours' fasting, after which the subject drank a solution of 100mg [sup 13]C-urea in 50 ml distilled water. The other breath sample was collected at 30 min post dosing. A positive test was defined as an increase in the ratio of 5 per mil over baseline. A questionnaire about dietary content was filled by each case. The δ[sup 13]C values of various Taiwanese foods were determined by continuous-flow isotope ratio mass spectrometory. Results: The Taiwanese food could be divided into two groups: the higher δ[sup 13]C value group (range from -10.4 to -20.6 per mil), and the lower δ[sup 13]C value group (range from -22.3 to -29.3 per mil). The mean δ[sup 13]C value of baseline measurement of adults was significant lower than that of children (-24.6±1.3 vs. -20.9±1.2; p < 0.01). This is probably because the Taiwanese children tend to consume more sugar, meat, and fat. If only a single 30-min sample was adopted to determine the H. pylori status, a further 5% false-positive and 1% false-negative results would occur. Conclusions: The baseline measurement in [sup 13]C-UBT for detection of H. pylori infection should not be omitted. There is variation in meanδ[sup 13]C value of baseline measurement in different age group and geographic area. These values may also be used as a dietary guideline for patients in the prevention of various diseases. [ABSTRACT FROM AUTHOR]

Introduction: Rabeprazole was shown to have a more rapid onset of action and greater antisecretory activity than other PPIs. Some investigators have suggested that a 4-day triple therapy involving rabeprazole achieves a comparable eradication rate of 90% with a 7-day triple therapy regimen. The cure rate of H. pylori is shown to be higher in CYP2C19 poor metabolizers (PMs) than in CYP2C19 extensive metabolizers (EMs). However, the metabolism of rabeprazole is usually considered to be less dependent of CYP2C19 genotypes. The aim of this study was to investigate the possible scenario for the effects of rabeprazole in the short-term treatment of H. pylori infection. Methods: Twenty mg of rabeprazole was given twice daily for 3 consecutive days then once daily at the fourth day to twelve healthy volunteers identified as CYP2C19 PMs or EMs. On day-1, aliquots of 10-ml blood samples were drawn 30 minutes before drug administration and 0.5, 1,2,3,4,5,6,7,8,10 and 12 hours after the starx of dosing. On day-4, blood samples were obtained as those in the first day except one additional 24-hour sample. Both pharmacokinetic (PK) and pharmacodynamic (PD) parameters were compared between different CYP2C19 genotype groups. Results: The plasma levels of both rabeprazole and rabeprazole thioether were much higher in CYP2CI9 PMs than in EMs, while there is no difference between day-1 and day-4 of dosing within the same genotype groups. In addition, only CYP2C19 PMs exhibit significant higher plasma gastrin levels on the fourth day compared to those on the first day. The PK/PD relationship of rabeprazole appears to be time-dependent. Conclusions: In terms of antisecretory and bacteriostatic effects, the PK/PD data suggest that CYP2C19 PMs might be subject to advantageous conditions for the treatment of H. pylori infection using rabeprazole, which might also provide rationale for the regimen design. [ABSTRACT FROM AUTHOR]