Twice-daily dosing of esomeprazole effectively inhibits acid secretion in CYP2C19 rapid metabolisers compared with twice-daily omeprazole, rabeprazole or lansoprazole

BACKGROUND

Twice-daily dosing of proton pump inhibitors (PPIs) is used to treat Helicobacter pylori or acid-related diseases, such as gastro-oesophageal reflux disease (GERD) refractory to standard dose of a PPI. Genetic polymorphisms of CYP2C19 are involved to different extents in the metabolism of four kinds of PPIs (omeprazole, lansoprazole, rabeprazole and esomeprazole) available in Japan.

AIM

To compare acid-inhibitory effects of the four PPIs dosed twice daily in relation to CYP2C19 genotype.

METHODS

We performed 24-h pH monitoring studies on Day 7 of PPI treatment for 40 Japanese H. pylori-negative volunteers [15 CYP2C19 rapid metabolisers (RMs), 15 intermediate metabolisers (IMs) and 10 poor metabolisers (PMs)] using a randomised four-way crossover design: omeprazole 20 mg, esomeprazole 20 mg, lansoprazole 30 mg and rabeprazole 10 mg twice daily.

RESULTS

Although median pH values with esomeprazole, omeprazole, lansoprazole and rabeprazole were 5.7 (3.5-7.2), 5.5 (2.4-7.2), 5.5 (3.7-7.3) and 5.2 (2.5-7.3), respectively (no statistically significant differences), CYP2C19 genotype-dependent differences were smaller for esomeprazole and rabeprazole compared with values for omeprazole and lansoprazole. In CYP2C19 RMs, the median pH with esomeprazole [5.4 (3.5-6.8)] was significantly higher than those with omeprazole [5.0 (2.4-5.9), P = 0.018], lansoprazole [4.7 (3.7-5.5), P = 0.017] or rabeprazole [4.8 (2.5-6.4), P = 0.002]. In IMs and PMs, the median pH was >5.0 independent of the PPI.

CONCLUSIONS

In intermediate and rapid metabolisers of CYP2C19, PPIs dosed twice daily could attain sufficient acid suppression, while in CYP2C19 RMs, esomeprazole 20 mg twice daily caused the strongest inhibition of the four PPIs. Therefore, esomeprazole may be effective in Japanese population when dosed twice daily.

Randomised clinical trial: rabeprazole improves symptoms in patients with functional dyspepsia in Japan

BACKGROUND

The efficacy of proton pump inhibitors (PPIs) for treating functional dyspepsia (FD) is not well established.

AIM

This study, named the SAMURAI study, aimed to assess the efficacy and dose-response relationship of rabeprazole in Japanese patients with FD in a multicentre, double-blinded, randomised, placebo-controlled trial.

METHODS

Investigated FD was diagnosed using the Rome III criteria. Subjects who did not respond to 1 week of single-blind placebo treatment in a run-in period were randomly assigned to 8 weeks of double-blind treatment with rabeprazole 10 mg, 20 mg, 40 mg or placebo, once daily. Dyspeptic symptoms were assessed by a dyspepsia symptom questionnaire (7-point Likert scale) and symptom diary.

RESULTS

Of 392 subjects entered into the run-in period, 338 were randomly assigned. Although there was no significant difference between placebo and rabeprazole groups in complete symptom relief for four major dyspeptic symptoms, the satisfactory symptom relief of rabeprazole 20 mg was significantly higher than placebo according to the dyspepsia symptom questionnaire (45.3% vs. 28.2%, P = 0.027) and the symptom diary assessment (48.7% vs. 30.0%, P = 0.016). The efficacy was not influenced by syndrome type or Helicobacter pylori status. No statistically significant differences in the incidence of adverse events were seen among treatment groups.

CONCLUSIONS

Rabeprazole 20 mg once daily but not 10 or 40 mg significantly provides satisfactory symptom relief for functional dyspepsia (ClinicalTrials.gov, Number NCT01089543).

A cyclochiral conformational motif constructed using a robust hydrogen-bonding network

A novel conformational motif constructed with a robust intramolecular hydrogen-bonding (H-bonding) network was discovered. A pyrrolidine derivative possessing four identical amide substituents at C(2) and C(5) formed a strong intramolecular H-bonding network consisting of all the amide groups. This conformation yielded a cyclochiral structure with a handedness that depended on the directionality of the H-bonding network. The most stable compound was isolated and applied to the acylative kinetic resolution of secondary alcohol. The handedness of the H-bonding network was biased by the presence of chiral substituents, and the preferred direction could be switched under an external stimulus. A structural analysis using NMR, X-ray crystallography, and theoretical calculation techniques indicated that the conformation of the substituents was highly ordered and depended on the directionality of the H-bonding network.

Visualization of angiographical arteriovenous shunting in perisylvian glioblastomas

BACKGROUND

Arteriovenous shunting visualized by angiography is one of the major features of glioblastomas, and the visualization is dependent on the presence of extensive shunting. Extensive arteriovenous shunting is associated with the risk of poorly controlled intraoperative bleeding. When a tumor with extensive arteriovenous shunting is located in close proximity to the eloquent regions of the brain, a meticulous surgical procedure is necessary. In the present study, the site-oriented visualization of angiographical arteriovenous shunting was evaluated from the perspective of surgical treatment, with a particular focus on the perisylvian region that is in close proximity to motor and language regions (dominant hemisphere), as well as large arteries and veins.

METHODS

Twenty-six consecutive patients underwent a resection of glioblastoma between February 2007 and September 2012. All patients were presurgically examined using digital subtraction angiography. The patients were subdivided into the following two groups based on the location of the tumor: 1) perisylvian glioblastoma (18 patients) and 2) non-perisylvian glioblastoma (eight patients). Angiography to detect the arteriovenous shunting was performed. In addition, the number of intratumoral vessels, tumor proliferative activity (MIB-1 labeling index), and volume of intraoperative bleeding were evaluated and compared between the two groups.

RESULTS

Angiographical arteriovenous shunting was definitively visualized in 13 of 18 (72 %) perisylvian glioblastomas, in contrast to only one of eight (13 %) non-perisylvian glioblastomas (p = 0.007). There were no significant differences between the two groups with respect to the number of intratumoral vessels, MIB-1 labeling index, and volume of intraoperative bleeding. However, massive intraoperative bleeding of > 2,000 mL occurred in one perisylvian glioblastoma patient.

CONCLUSIONS

Glioblastomas in the perisylvian region tend to be associated with extensive arteriovenous shunting that can be definitively visualized by performing an angiography. Because arteriovenous shunting carries the risk of intraoperative bleeding, perisylvian glioblastomas-particularly in the dominant hemisphere-should be resected with a meticulous surgical procedure and strategy.

Asymmetric desymmetrization of meso-diols by C(2)-symmetric chiral 4-pyrrolidinopyridines

In this work we developed C₂-symmetric chiral nucleophilic catalysts which possess a pyrrolidinopyridine framework as a catalytic site. Some of these organocatalysts effectively promoted asymmetric desymmetrization of meso-diols via enantioselective acylation.

Rapid renaturation of denatured and aggregated proteins using liquid paraffin as a pseudolipid bilayer membrane

A means of rapidly renaturing denatured protein was devised and evaluated. Three liquids were laminarly layered in a centrifuge tube, in which two solutions sandwiched liquid paraffin so as to form a pseudolipid bilayer. Denatured and aggregted protein placed on the upper surface of liquid paraffin was renatured as it passed through liquid-paraffin layer into the renaturation buffer during the centrifugation. The aggregated and denatured protein selectively passed through the liquid-paraffin layer, whereas other solutions, such as chaotropic agents or organic solvent, could not. This means that a rapid dilution condition favorable for protein renaturation was realized in a small scale. Aggregated and denatured BSA and ribonuclease A were renatured and resolubilized as they passed through the liquid-paraffin layer into an appropriate renaturation buffer solution. This method was also applied to the rapid heme reconstitution of myoglobin from Feprotoporphyrin IX to Zn-protoporphyrin IX. (c) 1994 John Wiley & Sons, Inc.

Rabeprazole 10 mg q.d.s. decreases 24-h intragastric acidity significantly more than rabeprazole 20 mg b.d. or 40 mg o.m., overcoming CYP2C19 genotype

BACKGROUND

Standard dosing (i.e. once daily) of proton pump inhibitors (PPIs) cannot inhibit acid secretion for a full 24 h. Better therapeutic regimens using PPIs are required to sustain potent acid inhibition for the full 24 h in all patients with acid-related diseases.

AIM

To evaluate acid inhibitory effects by different dosing times of a PPI at the same daily dosage, in a study involving 70 rounds of pH monitoring.

METHODS

Using pH monitoring, we evaluated the efficacy of different divided treatment regimens with the same total daily dose of rabeprazole (40 mg o.m., 15 rounds; 20 mg b.d., 20 rounds; 10 mg q.d.s., 35 rounds) on day 7 or 8 of PPI dosing.

RESULTS

In the study of divided treatment, the median pH (when administered once, twice or four times to achieve a daily dose of 40 mg) was 4.8 (3.6-6.4), 5.7 (4.1-7.4), 6.6 (4.9-8.4), respectively. When comparing the median pHs at the same CYP2C19 genotype among different dosing times of rabeprazole, the median pH attained with 10 mg q.d.s. was significantly higher than that in 40 mg o.m. or 20 mg b.d. Increase in the frequency of dosing effectively increased pH [median percent time of pH > 4.0 with q.d.s. therapy: 95.5% (63.2-100.0%)], irrespective to CYP2C19 genotype.

CONCLUSION

Four times daily dosing with rabeprazole 10 mg achieved potent acid inhibition, including during the night-time, suggesting its potential usefulness as a regimen for patients who are refractory to standard once daily PPI treatment.

Regioselective diversification of a cardiac glycoside, lanatoside C, by organocatalysis

Acylation of lanatoside C in the presence of organocatalyst 5 gave the C(4'''')-O-acylate in up to 90% regioselectivity (catalyst-controlled regioselectivity). Various functionalized acyl groups can be introduced at the C(4'''')-OH by a mixed anhydride method in the presence of 5 or the related organocatalyst. On the other hand, DMAP-catalyzed acylation of lanatoside C gave the C(3'''')-O-acylate in up to 97% regioselectivity (substrate-controlled regioselectivity). Thus, diverse regioselective introduction of acyl groups among eight free hydroxy groups of lanatoside C was achieved.

Analysis of N(ε) -ethyllysine in human plasma proteins by gas chromatography-negative ion chemical ionization/mass spectrometry as a biomarker for exposure to acetaldehyde and alcohol

BACKGROUND

N(ε) -ethyllysine (NEL) is a major stable adduct formed by the reaction of acetaldehyde (AA) with lysine residues in proteins. However, its occurrence and levels in biological specimens and its relationship with AA/alcohol exposure-associated disorders have not been fully elucidated. In this study, we have developed a sensitive and specific method to quantitate NEL levels in human plasma proteins.

METHODS

The method consists of (1) purification of the protein fraction of interest by Sephadex G-15 to remove low molecular substances, (2) hydrolysis of proteins with Pronase E in the presence of stable isotope-labeled internal standards, (3) derivatization of amino acids with pentafluorobenzyl (PFB) bromide, and (4) quantification of the PFB derivatives of NEL and l-lysine using gas chromatography-negative ion chemical ionization/mass spectrometry in a selected ion monitoring mode.

RESULTS

Using the above method, the NEL levels in human plasma proteins obtained from 10 each of control subjects and alcoholic patients were measured. NEL was detected in all samples analyzed, the average level of NEL in the plasma proteins of alcoholic patients (1.17 ± 0.36 NEL/1,000 l-lysine) being significantly higher than that of control subjects (0.26 ± 0.07 NEL/1,000 l-lysine).

CONCLUSIONS

The method could be applied to molecular epidemiological studies to investigate possible associations between the NEL levels in human tissue proteins and human diseases associated with exposure to AA and alcohol.