Investigation into the impact of proton pump inhibitors on sertraline transport across the blood-brain barrier

As a widely used antidepressant that works by inhibiting the reuptake of serotonin, sertraline exerts an antidepressant effect depending on its concentration in the brain, which might be limited by the blood-brain barrier (BBB). It is highly possible to combine proton pump inhibitors (PPIs) with sertraline in clinical trials. Nevertheless, the role played by PPIs in regulating the transport of sertraline across the BBB remains unclear. Here, the impact of PPIs on the distribution of sertraline in the brain and the mechanisms involved were investigated. A mouse brain distribution study showed that Omeprazole (OME), Pantoprazole (PAN), Ilaprazole (ILA), and Esomeprazole (ESO) increased the area under the brain concentration-time curves (AUC) for sertraline by 2.02-, 3.18-, 3.04-, and 4.21-fold, respectively, after the 14-day administration of PPIs. Besides, PPIs significantly increased the permeability of sertraline in brain perfusion experiments, with PAN having the highest rank order, followed by ILA, OME, and ESO. In the tail suspension test (TST), co-administration PPI groups showed significantly shorter immobility time than the control group. In vitro, four PPIs inhibited sertraline efflux in breast cancer resistance protein (BCRP)-overexpressing MDCKII cells, and showed a mixed inhibition type. In this study, PPIs were further found to inhibit the mRNA and protein expression of brain BCRP. To sum up, the findings of this study revealed that PPIs could enhance the brain distribution and antidepressant effect of sertraline, which may be attributed to the inhibition of BCRP expression at the BBB by PPIs.

Improved quantitative determination of (R)- and (S)-rabeprazole sodium and its metabolites in rat plasma by LC-MS/MS and its application to a toxicokinetic study

There exist two enantiomers: (R)- and (S)-rabeprazole. (R)-rabeprazole offers specific pharmacokinetic advantages and enhanced therapeutic efficacy, warranting further investigation and development. Here, we developed a simple and rapid chiral liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to simultaneously quantify rabeprazole enantiomers and their metabolites (rabeprazole sulfoxide and desmethyl rabeprazole enantiomers) and a LC-MS to quantify rabeprazole thioether. As for the chiral LC-MS/MS method, Chiral-AGP column (150 × 4 mm, 5 μm) was used and its mobile phase was acetonitrile (mobile phase A) and 10 mmol/L ammonium acetate (mobile phase B) (linear gradient profile: 0 min, 10 % B; 5 min, 15 % B; 9 min, 15 % B; 9.01 min, 10 % B; 13 min, 10 % B). The multiple reactions monitoring transitions of m/z 360.3 → 242.1, 376.2 → 240.1, 346.2 → 228.2 and 368.2 → 190.2 were opted for quantifying rabeprazole enantiomers, rabeprazole sulfoxide, desmethyl rabeprazole enantiomers and internal standard omeprazole. The analyte samples were prepared by a simple liquid-liquid extraction method. As for the LC-MS method, analytes were separated on a Inertsil® ODS-3 column (4.6 × 150 mm, 5 μm). The mobile phase was acetonitrile-5 mmol/L ammonium acetate water solution (65:35, v/v). ESI+ was used and ion peaks with m/z 344.2 (rabeprazole thioether) and 285.1 (internal standard diazepam) were monitored. Both these 2 methods were validated for specificity, linearity, precision, accuracy, matrix effect and extraction recovery, and, particularly, the stability of analytes under various conditions. We successfully applied these methods to a 13-week toxicokinetic study of rabeprazole in rats after intravenous administration of (R)- (80, 20, 5 mg/kg/d) and racemic (80 mg/kg/d) rabeprazole sodium. The results showed that rabeprazole and its metabolites did not accumulate in rats. However, desmethyl rabeprazole and rabeprazole thioether showed higher exposure and lower clearance rate in the last administration than in the first one. (R)-rabeprazole showed a higher exposure and a slower elimination rate than (S)-rabeprazole in rats. These findings offer experimental evidence and a theoretical foundation for further preclinical investigations and clinical applications of (R)-rabeprazole.

Stereoselective separation of omeprazole and 5-hydroxy-omeprazole using dried plasma spots and a heart-cutting 2D-LC approach for accurate CYP2C19 phenotyping

Omeprazole (OME) is a widely used gastric proton pump inhibitor, marketed as a racemic mixture comprising (S)- and (R)-enantiomers, with distinct pharmacokinetic profiles. OME is primarily metabolized by the cytochrome P450 enzymes 2C19 (CYP2C19) and 3A4 (CYP3A4). OME is a conventional probe for CYP2C19 phenotyping. Accurate measurement of these enantiomers and their metabolites is essential for pharmacokinetic studies. This article presents a sensitive and accurate two-dimensional liquid chromatography-mass spectrometry (LC-MS/MS) method for the simultaneous quantification of OME enantiomers and its hydroxylated metabolite (5-hydroxyomeprazole) in human plasma. The method involves an online extraction using an achiral Discovery HS C18 trapping column for purification (20 × 2.1 mm ID, 5μm particle size, Supelco) and subsequent forward flush elution onto a chlorinated phenylcarbamate cellulose-based chiral column (150x2mm ID, 3 μm particle size, Lux Cellulose-4, Phenomenex). The assay was fully validated and met international validation criteria for accuracy, precision, and stability and ensured high selectivity and sensitivity within a short runtime (<8 min). Application of this method to clinical samples demonstrated its utility in studying OME enantiomer pharmacokinetics, particularly its potential for phenotyping the activity of the CYP2C19 isoenzyme. This robust analytical approach offers a valuable tool for clinicians and researchers studying OME's pharmacokinetics, providing insights into its metabolism and potential implications for personalized medicine.

Proton Pump Inhibitors and Bone Health: An Update Narrative Review

Proton pump inhibitors (PPIs) are an antacid drug often used in acid-related disorders. They decrease acid secretion in the stomach by blocking an enzyme called H+/K+ ATPase which controls acid production. Introduced to the market in 1989, their use has increased rapidly worldwide and they are now among the top 10 most prescribed drugs in the United States. As of 2015, the FDA has already approved six drugs of this class (omeprazole, esomeprazole, lansoprazole, dexlansoprazole, pantoprazole and rabeprazole). Recently, the risks and benefits of long-term PPI use were questioned and many studies indicated that their use should be carefully considered, especially in young patients, whose treatment with these drugs could last many years. Even greater concerns have been raised about a potential positive association between PPIs and osteoporotic fracture risk including the hip, spine and wrist. Although based on observational studies, there is substantial evidence associating the long-term use of PPIs and fracture. This relationship is only partially admitted due to the lack of consistent effects of PPIs on bone mineral density loss. Therefore, this narrative review aimed to discuss the recent findings pertaining to the risk of osteoporotic fracture associated with PPIs, in particular prolonged use, and to call for further research to elucidate the mechanisms associated with this bone fragility.

Proton pump inhibitors associated with rapid eye movement sleep behaviour disorder

We present the case of a 65-year-old woman diagnosed with rapid eye movement sleep behaviour disorder (REMBD) based on typical symptoms and confirmed with an inpatient polysomnogram. She was prescribed clonazepam and later temazepam but continued to have intrusive symptoms. She subsequently recalled that the onset of dream enactment coincided with starting high-dose omeprazole for acid reflux. With this insight, she stopped the omeprazole. Within days, the dream enactment and nocturnal movements subsided. She stopped taking the temazepam and was symptom free for a few months. However, she was started on lansoprazole for recurrent dyspepsia. Once again she experienced violent movements in sleep. This is the first time an association between proton pump inhibitors (PPIs) and REMBD has been reported. PPIs have many effects on the central nervous system and should be considered as a possible provoking factor in people presenting with REMBD.

Pantoprazole-lnduced Thrombocytopenia

Objective:

To report 2 cases of thrombocytopenia associated with pantoprazole treatment and discuss existing reports on this drug-induced adverse event.

Case Summaries:

This paper describes the course of thrombocytopenia associated with pantoprazole 40 mg in 2 hospitalized patients. In both cases, thrombocytopenia appeared after the initiation of pantoprazole and rapidly improved after discontinuation of pantoprazole, although complete resolution of thrombocytopenia occurred in only one patient prior to discharge from the hospital.

Discussion:

The mechanism of drug-induced thrombocytopenia is often poorly understood, and proton-pump inhibitors are generally not strongly suspected as a cause of thrombocytopenia. However, an objective causality assessment using the Naranjo probability scale revealed a probable relationship between thrombocytopenia and pantoprazole in both of the cases. It is unknown whether this is a class effect.

Conclusions:

Although drug-induced thrombocytopenia with pantoprazole appears to be rare, it represents a potentially severe adverse effect. This supports the judicious prescribing of pantoprazole and possibly other proton-pump inhibitors.

Role of Autophagy as a Survival Mechanism for Hypoxic Cells in Tumors

Enhanced autophagy has been observed in hypoxic regions of solid tumors. Here we address the hypothesis that autophagy is required for survival of hypoxic cells. We evaluated sensitivity to hypoxia of three human tumor cell lines (MCF7, PC3, and LNCaP) and their autophagy-deficient variants with shRNA knockdown of the genes ATG7 and BECLIN1. Hypoxia-induced cell death was more rapid for autophagy-deficient cells and was increased in the presence of the proton pump inhibitor pantoprazole that inhibits autophagy. Autophagy-deficient cells had a lower rate of oxygen consumption than wild-type cells. In xenografts derived from the three cell lines, autophagy (as determined by increased LC3 and reduced p62/SQSTM1) colocalized with hypoxic regions (identified by EF5). Xenografts derived from autophagy-deficient cells grew more slowly than wild-type tumors. Both LC3 expression and hypoxia were decreased in xenografts generated from single-knockdown cells and absent in double-knockdown tumors. Our results are consistent with the hypothesis that autophagy facilitates the survival of hypoxic cells, although reduced oxygen consumption of autophagy-deficient cells may contribute to lack of hypoxia in tumors derived from them. Because hypoxia is associated with resistance to anticancer therapy, inhibition of autophagy has potential to enhance the effectiveness of cancer treatment.

Rabeprazole: the role of proton pump inhibitors inHelicobacter pylorieradication

Proton pump inhibitors have become one of the cornerstones in the treatment of Helicobacter pylori infection. Rabeprazole (Pariet) is a substituted benzimidazole proton pump inhibitor with potent gastric acid suppression properties. Its high acid-base dissociation constant allows activation over a broader pH range, resulting in quick, irreversible binding to the H+/K+-ATPase pump, and a more rapid onset of action compared with omeprazole, lansoprazole and pantoprazole. Unlike other proton pump inhibitors, the metabolism of rabeprazole is primarily via a nonenzymatic reduction to the thioether derivative, and the cytochrome P450 isoenzyme 2C19 is only partly involved in its metabolism. The effect of genetic polymorphism in cytochrome P450 isoenzyme 2C19 on the pharmacokinetics and pharmacodynamics of rabeprazole is therefore limited. In humans, once-daily dosing of 5-40 mg of rabeprazole inhibits gastric acid secretion in a dose-dependent manner. In vitro studies have shown that rabeprazole possesses more potent antibacterial properties against the growth of H. pylori than other proton pump inhibitors. Furthermore, its thioether derivative has more potent inhibitory in vitro activity against the growth and motility of clarithromycin-resistant H. pylori than other proton pump inhibitors or commonly used antimicrobials. Despite these inherent favorable characteristics of rabeprazole, randomized controlled trials have largely shown equivalence amongst proton pump inhibitors when used with two antibiotics in the eradication of H. pylori, with cure rates of 75-89% on an intent-to-treat basis. However, rabeprazole appears to consistently achieve such comparable eradication rates even when used at reduced doses (10 mg twice daily) as part of clarithromycin-based triple therapy.

Coadministration of Lansoprazole and Naproxen Does Not Affect the Pharmacokinetic Profile of Methotrexate in Adult Patients With Rheumatoid Arthritis

Drugs prescribed for rheumatoid arthritis are often associated with gastrointestinal toxicity, and proton pump inhibitors may be coadministered for gastroprotection. In this open-label study, the effect of lansoprazole 30 mg qd and naproxen 500 mg bid on the pharmacokinetic profile of methotrexate was investigated. Twenty-seven adult rheumatoid arthritis patients on stable oral methotrexate doses (7.5-15 mg/week) for a minimum of 3 months were enrolled. Methotrexate pharmacokinetics were assessed on days -1 (methotrexate alone) and 7 (methotrexate with lansoprazole and naproxen). Pharmacokinetics of methotrexate and 7-hydroxymethotrexate were not altered by coadministration of methotrexate with lansoprazole and naproxen; point estimates and 90% confidence intervals for the peak plasma concentration and area under the plasma concentration-time curve of methotrexate and 7-hydroxymethotrexate were within the 0.80 to 1.25 boundaries. Therefore, coadministration of naproxen and lansoprazole for 7 days does not affect the pharmacokinetic profile of low doses of methotrexate.

Ilaprazole for the treatment of duodenal ulcer: a randomized, double-blind and controlled phase III trial

OBJECTIVE

The new proton pump inhibitor (PPI), ilaprazole performed better at the dose of 10 mg/d relative to 5 or 20 mg/d in a previous phase II trial. A larger phase III trial was carried out to confirm the efficacy and safety of ilaprazole (10 mg/d) compared with omeprazole (20 mg/d) and provide some characteristics of the relationship between ilaprazole metabolism and CYP2C19 for later studies.

RESEARCH DESIGN AND METHODS

Patients with at least one endoscopically diagnosed active duodenal ulcer (DU) were enrolled in a multicenter, randomized, double-blind, positive controlled trial and then assigned randomly to the ilaprazole group (10 mg/d) or the omeprazole group (20 mg/d) with a sample allocation ratio 2:1. The course of treatment was 4 weeks.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov registration number: NCT00952978.

MAIN OUTCOME MEASURES

The primary endpoint was endoscopically diagnosed ulcer healing rate at week 4. Symptom relief was evaluated as a secondary endpoint by graded scores. Safety and tolerability were evaluated on basis of clinical assessments. In addition, blood samples were collected at baseline for CYP2C19 genotypes identification.

RESULTS

Efficacy analyses were based on 494 patients. At week 4, the ulcer healing rates were 93.0% in ilaprazole group and 90.8% in omeprazole group (rate difference: 2.2%; 95% confidence interval: -2.8% to 7.2%). No obvious variation of healing rate on different CYP2C19 genotypes was found in ilaprazole group. The majority of patients (>80%) became asymptomatic after treatment. Incidences of adverse drug reactions were similar between ilaprazole group and omeprazole group (8.5% vs. 11.5%).

CONCLUSIONS

Ilaprazole (10 mg/d) is as effective as omeprazole (20 mg/d) in the treatment of DU with similar side effects. The efficacy of ilaprazole is not affected by CYP2C19 polymorphisms.

Investigation on the interaction between ilaprazole and bovine serum albumin without or with different C-ring flavonoids from the viewpoint of food-drug interference

The interaction between ilaprazole and bovine serum albumin (BSA) has been investigated in the absence and presence of four popular flavonoids with different C-ring structures, quercetin, luteolin, taxifolin, and (+)-catechin, by means of fluorescence spectroscopy. The results indicated that ilaprazole had a strong ability to quench the intrinsic fluorescence of BSA, and site marker competitive experiments indicated that the binding of ilaprazole to BSA primarily took place in subdomain IIA. The quenching process of ilaprazole with BSA was easily affected by flavonoids,; however, they did not change the quchenching mechanism of ilaprazole with BSA, whereas all of the fluorescence quenching was initiated by a static quenching procedure combining with nonradiative energy transfer. The presence of flavonoids decreased the quenching constants of ilaprazole with BSA from 2.2 to 23.7% and decreased the binding constants from 73.7 to 98.3%, which depended on the different flavonoids' structures. The decreased binding constants and unchangeable spatial distance of ilaprazole with BSA by the introduction of quercetin, luteolin, and taxifolin may result from the competition of flavonoids and ilaprazole binding to BSA, whereas in the presence of (+)-catichin, decreased binding constants and increased spatial distance possibly resulted from the formation of a ternary ilaprazole-BSA-(+)-catechin complex. All of these results may have relevant consequences in rationalizing the interferences of common food to gastric ulcer treatments.

[Evaluation of the effect of ilaprazole on intragastric pH in patients with duodenal ulcer]

OBJECTIVE

To evaluate the effect of ilaprazole enteric tablets on intragastric pH in duodenal ulcer patients.

METHODS

A randomized, double blind, positive controlled clinical trial was carried out. A total of forty-two patients with duodenal ulcer were randomized into low dose ilaprazole group (5 mg/d), medium dose ilaprazole group (10 mg/d), high dose ilaprazole group (20 mg/d) and omeprazole group (20 mg/d). An ambulatory 24 hour intragastric pH study was performed at the fifth treatment day. Fraction time pH above 3, 4 or 5, median values of 24 hour diurnal pH and 12 hour nocturnal pH, the percentage of patients with total time pH above 3, 4 or 5 at least for 18 hours were evaluated.

RESULTS

There were no significant differences of fraction time pH above 3 or 4, median values of 24 hour diurnal pH and 12 hour nocturnal pH and the percentage of patients with total time pH above 3, 4 or 5 at least for 18 hours among all the groups with different doses of ilaprazole and the omeprazole group. The fraction time pH above 5 in medium and high dose ilaprazole groups were (87.96 + or - 12.29)% and (89.86 + or - 15.18)% respectively, which was higher than that in low dose ilaprazole group [(67.17 + or - 30.16)%] and omeprazole group [(76.14 + or - 16.75)%], P < 0.05.

CONCLUSION

Ilaprazole has a strong effect on intragastric acid control with a dose dependent trend.

Gastroprotective activity of a new semi-synthetic solidagenone derivative in mice

The gastroprotective activity of the new semi-synthetic solidagenone derivative 15,16-epoxy-8(9),13(16),14-labdatrien-7β-methoxy-6β-ol (ELMO) has been assessed on the model of HCl/EtOH-induced gastric lesions in mice. Human gastric epithelial cells (AGS) and fibroblasts (MRC-5) were used to determine its mode of action. The effect of ELMO on the prostaglandin E2 content, cellular reduced glutathione (GSH) and protection against damage induced by sodium taurocholate was assessed against AGS cells. The effect of ELMO on the growth of AGS and fibroblast cultures was evaluated. The superoxide anion scavenging capacity of the compound was studied also. The cytotoxicity of ELMO, expressed as cell viability, was assessed using two independent endpoints: neutral red uptake (NRU) and the reduction of 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) for MRC-5 fibroblasts and NRU for AGS cells. A single oral dose of ELMO (10 and 20 mg kg−1) inhibited the appearance of gastric lesions in mice displaying similar values to lansoprazole at 20 mg kg−1. At 40 μm ELMO increased the prostaglandin E2 content but not GSH in AGS cells. The compound showed no effect on sodium taurocholate-induced damage and was devoid of superoxide anion scavenging activity. Concentrations of 0.5, 1, 2 and 4 μm stimulated fibroblast but not AGS cell proliferation. The compound showed weak cytotoxicity with values (IC50) of 411 (NRU) and 418 μm (MTT) for fibroblasts and 261 μm (NRU) for AGS cells. The results support further pharmacological study of this compound as a potential new anti-ulcerogenic drug.

Randomized, parallel, double-blind comparison of the ulcer-healing effects of ilaprazole and omeprazole in the treatment of gastric and duodenal ulcers

PURPOSE

Ilaprazole (IY-81149) is a new proton-pump inhibitor (PPI) not previously studied in human patients with ulcer disease. This study evaluated and compared it with a reference PPI, omeprazole, in the treatment of gastric and duodenal ulcers.

METHODS

This was a double-blind, parallel, randomized study. Patients aged 18 years and above with at least one endoscopically confirmed active non-malignant gastric/duodenal ulcer were treated with 20 mg/day omeprazole or 5 mg/day or 10 mg/day ilaprazole for four weeks. Healing of ulcer was determined by its resolution from active to scarring stage. Symptoms relief was evaluated using a graded score. Safety and tolerability were evaluated on basis of clinical assessments. Between-group differences were tested using ANOVA or ANCOVA, as appropriate. Statistical significance was assumed at a two-tailed p value of </=0.05.

RESULTS

Two hundred and twelve gastric ulcer patients (median age 53.3 years) and 306 duodenal ulcer patients (median age 49.7 years) were recruited; 71.8 and 85% of gastric and duodenal ulcer patients, respectively, completed the study. Ulcers were successfully healed in 64.29, 67.14, and 63.89% of gastric ulcer patients and 78.85, 83.65, and 78.57% of duodenal ulcer patients after treatment with 20 mg omeprazole, 5 mg ilaprazole, and 10 mg ilaprazole, respectively. Most patients (>90%) became asymptomatic after treatment. At the dosages administered, both drugs exhibited similar efficacy and a similar safety profile.

CONCLUSIONS

Ilaprazole is as tolerable, safe, and efficacious as omeprazole in the treatment of gastroduodenal ulcers, at a much lower dose (5 vs. 20 mg omeprazole).

Application of a stability-indicating thin-layer chromatographic method to the determination of tenatoprazole in pharmaceutical dosage forms

A sensitive, selective, precise, and stability-indicating thin-layer chromatographic (TLC) method was developed and validated for the determination of tenatoprazole both as a bulk drug and in formulation. The method uses TLC aluminum plates precoated with Silica Gel 60F-254 as the stationary phase and the solvent system toluene-ethyl acetate-methanol (6 + 4 + 1, v/v/v). This system gave compact spots for tenatoprazole (Rf value of 0.34 +/- 0.02). Tenatoprazole was subjected to acid and alkali hydrolysis, oxidation, and photodegradation. The peaks of the degradation products were well-resolved from that of the pure drug and had significantly different Rf values. Densitometric analysis of tenatoprazole was performed in the absorbance mode at 306 nm. The linear regression analysis data for the calibration plots showed a good linear relationship over the concentration range of 100-1500 ng/spot. The mean values of the correlation coefficient, slope, and intercept were 0.9989 +/- 1.42, 10.27 +/- 0.965, and 4894.2 +/- 1.24, respectively. The method was validated for precision, robustness, and recovery. The limit of detection and limit of quantitation were 50 and 100 ng/spot, respectively. Statistical analysis showed that the method is repeatable and selective for estimation of tenatoprazole. Because the method can separate the drug from its degradation products, it can be used to monitor stability.

[Why some proton pump inhibitors are more equal than others]

After the omeprazole patent expired in 2002, numerous generic products were introduced on the market. In a relatively short time many patients received substituted treatment. Clinicians noted a substantial number of patients with more reflux symptoms. We describe a male surgeon of 61 and a woman of 59 both with the red flag symptom of dysphagia after generic substitution. The first patient received a generic substitute of omeprazole, the second a therapeutic substitute of pantoprozole, i.e. omeprazole. The literature suggests three possibilities to explain the inadequacy of the substitution: (a) biphasic metabolism where the raised pH in the stomach may prematurely inactivate the PPI, with an unpredictable effect, (b) differences in acid-resistant coating of the generic products, and (c) influence of multiple dosing of PPIs after several days' use. We conclude that all three factors may contribute to a difference in absorption and therefore clinical effectiveness.

Long-term efficacy of Helicobacter pylori eradication in patients with idiopathic thrombocytopenic purpura: 7-year follow-up prospective study

Helicobacter pylori eradication is useful for improvement of a half of patients with idiopathic thrombocytopenic purpura (ITP), but its long-term therapeutic efficacy has not been elucidated. We investigated the long-term efficacy of H. pylori eradication in 30 cases with ITP that were included in our previous study regarding the association between H. pylori infection and ITP. Twenty-one cases were positive and nine cases were negative for H. pylori infection. H. pylori eradication therapy including secondary regimen was successful in 20 cases, half (responder) of whom showed ITP remission 1 month later. Nine responders could be followed up for a long time and did not show re-infection of H. pylori. Eight of nine needed no medication except for eradication therapy. Another case remained in remission for 1 year but thereafter needed a steroid therapy due to the recurrence. Eight nonresponders could be followed up for a long time. All these cases showed a bad clinical course even though they received the other post-treatments including steroid therapy. Three of nine H. pylori-negative cases underwent eradication therapy after obtaining the written informed consent, but none of them showed improvement. Of these three cases, two cases could be followed up. Only one case remained a remission although receiving corticosteroid as a post-treatment. Conditions of H. pylori-negative ITP cases were usually unstable for a long time. H. pylori eradication has a short-term efficacy for about half of H. pylori-positive ITP patients, and the responders to the eradication therapy may receive a long-term clinical benefit without other therapies.

Lansoprazole promotes gastric mucosal cell proliferation and migration by activating p44/p42 mitogen-activated protein kinase

Cell proliferation and migration are important repair mechanisms in cell defect type mucosal injuries, such as peptic ulcers. To evaluate the level of cell restitution in vitro, we established a normalized assay system for analyzing the area of a tissue defect created in the center of a cultured cell layer. Although proton pump inhibitors are known to be potently effective in the treatment of peptic ulcers by inducing acid suppression, they are also effective in low-acid conditions, such as in gastric ulcers associated with severe atrophic gastritis of the corpus. The present study was designed to examine the pH-independent effect of lansoprazole (LPZ) on cell restitution in vitro. The mouse gastric mucosal cell line, GSM06, was cultured to confluence. A 4-fluoric ethylene-tipped aluminum stick was then used to produce a cell-free area in the center of the culture well. After measuring the area of the cell defect using a digital analyzer equipped with an inverted microscope, LPZ was added to each well; the area of the residual cell defect was then measured 6 and 24 hours after LPZ administration. To investigate the involvement of the p44/p42 mitogen-activated protein kinase (MAPK) and p38 MAPK in this process, PD98059 (a MEK inhibitor) or FR167653 (a p38 MAPK inhibitor) was added to the cell cultures. In a separate experiment, GSM06 cells were cultured to the subconfluent level, each test agent was added, and the cell number in each well was measured using an MTT assay 16 hours after the administration of the agents. Six hours after the addition of LPZ, a slight but significant increase in the cell restitution rate was observed in the LPZ-treated groups compared with that in the control group. After 24 hours, a further significant increase in the cell restitution rate was observed in the LPZ groups compared with that in the control group. While the addition of PD98059 significantly attenuated the cell restitution rate in the LPZ groups, the addition of FR167653 had no such effect. The total cell number in the subconfluent cell cultures was significantly increased in the LPZ-treated groups compared with that in the control group. In conclusion, LPZ promotes the healing of injured gastric mucosal cells following injury by enhancing cell proliferation and migration. Furthermore, the mechanism by which cell proliferation and migration is promoted by LPZ may involve the activation of p44/p42 MAPK.

Identification and relative contributions of human cytochrome P450 isoforms involved in the metabolism of glibenclamide and lansoprazole: evaluation of an approach based on thein vitrosubstrate disappearance rate

1. The identification and relative contributions of human cytochrome P450 (CYP) enzymes involved in the metabolism of glibenclamide and lansoprazole in human liver microsomes were investigated using an approach based on the in vitro disappearance rate of unchanged drug. 2. Recombinant CYP2C19 and CYP3A4 catalysed a significant disappearance of both drugs. When the contribution of CYPs to the intrinsic clearance (CL(int)) of drugs in pooled human microsomes was estimated by relative activity factors, contributions of CYP2C19 and CYP3A4 were determined to be 4.6 and 96.4% for glibenclamide, and 75.1 and 35.6% for lansoprazole, respectively. 3. CL(int) of glibenclamide correlated very well with CYP3A4 marker activity, whereas the CL(int) of lansoprazole significantly correlated with CYP2C19 and CYP3A4 marker activities in human liver microsomes from 12 separate individuals. Effects of CYP-specific inhibitors and anti-CYP3A serum on the CL(int) of drugs in pooled human liver microsomes reflected the relative contributions of CYP2C19 and CYP3A4. 4. The results suggest that glibenclamide is mainly metabolized by CYP3A4, whereas lansoprazole is metabolized by both CYP2C19 and CYP3A4 in human liver microsomes. This approach, based on the in vitro drug disappearance rate, is useful for estimating CYP identification and their contribution to drug discovery.

Intestinal CYP3A4 is not involved in the enantioselective disposition of lansoprazole

The contribution of (S)-lansoprazole to CYP3A4-catalysed sulfoxidation is greater than that of (R)-lansoprazole. The aim was to investigate the effect of grapefruit juice on the enantioselective disposition of lansoprazole among three CYP2C19 genotype groups. Eighteen healthy subjects, consisting of six each of homozygous extensive metabolizers (homEMs), heterozygous extensive metabolizers (hetEMs) and poor metabolizers (PMs), ingested a single oral dose of 60 mg racemic lansoprazole after taking either 200 ml grapefruit juice or water. There was no effect of grapefruit juice on the mean maximum plasma concentrations (C(max)) or the elimination half-life for each lansoprazole enantiomer in all three CYP2C19 genotype groups. Similarly, the pharmacokinetic parameters of lansoprazole sulfone remained unaltered by grapefruit juice in all three groups. The CYP3A4-mediated first-pass sulfoxidation of (R)- and (S)-lansoprazole were not influenced by grapefruit juice. In addition, stereoselectivity of the intestinal CYP3A4-catalysed sulfoxidation of (R)- and (S)-lansoprazole was not observed.

Stereoselective inhibition of cytochrome P450 forms by lansoprazole and omeprazolein vitro

The stereoselectivity of the inhibitory interaction potential of lansoprazole and omeprazole isomers on six human cytochrome P450 forms was evaluated using human liver microsomes. Lansoprazole enantiomers showed stereoselective inhibition of CYP2C9-catalysed tolbutamide 4-methylhydroxylation, CYP2C19-catalysed S-mephenytoin 4'-hydroxylation, CYP2D6-catalysed dextromethorphan O-demethylation, CYP2E1-catalysed chlorzoxazone 6-hydroxylation and CYP3A4-catalysed midazolam 1-hydroxylation, whereas omeprazole only inhibited CYP2C19 stereoselectively. Of the P450 forms tested, CYP2C19-catalysed S-mephenytoin 4'-hydroxylation was extensively inhibited by both the lansoprazole and omeprazole enantiomers in a competitive and stereoselective manner; the S-enantiomers of both drugs inhibited the hydroxylation more than the R-enantiomers. The estimated K(i) values determined for CYP2C19-catalysed S-mephenytoin 4'-hydroxylation were 0.6, 6.1, 3.4 and 5.7 microM for S-lansoprazole, R-lansoprazole, S-omeprazole and R-omeprazole, respectively. The results indicate that although both lansoprazole and omeprazole are strong inhibitors of CYP2C19, the inhibition of CYP2C19 by lansoprazole is highly stereoselective, whereas the inhibition by omeprazole is less stereoselective. In addition, S-lansoprazole, the most potent CYP2C19 inhibitor, is not a good CYP2C19-selective inhibitor owing to its inhibition of other P450 forms.

Comparison of enantioselective disposition of rabeprazole versus lansoprazole in renal-transplant recipients who are CYP2C19 extensive metabolizers

The purpose of this study was to investigate the comparative pharmacokinetics of rabeprazole and lansoprazole enantiomers in renal-transplant recipients on tacrolimus who were CYP2C19 extensive metabolizers. Sixteen Japanese patients were randomly assigned after renal transplantation to receive repeated doses of one of the following two regimens for 28 days; tacrolimus, mycophenolate mofetil and prednisolone together with either 20mg of racemic rabeprazole (n=8) or 30 mg of racemic lansoprazole (n=8). The mean Cmax and AUC0-24 of (R)-lansoprazole compared to (S)-lansoprazole in renal transplant recipients were 12-fold (954+/-522 vs. 167+/-137 ngml(-1), respectively) and 6.9-fold (4787+/-3454 vs. 451+/-354 nghml(-1), respectively) greater, and its elimination half-life was 2.1-fold (2.3+/-1.0 vs. 1.2+/-0.6h, respectively) longer. In contrast, although the elimination half-life of (R)-rabeprazole was significantly longer than that of the (S)-enantiomer (2.1+/-0.5 vs. 1.3+/-0.9h, respectively; P<0.05), there was no difference in Cmax between the (R)- and (S)-enantiomer (186+/-40 vs. 200+/-92 ngml(-1), respectively). In conclusion, in renal-transplant recipients who are CYP2C19 extensive metabolizers, there is less stereoselective difference in the pharmacokinetic disposition between the (R)- and (S)-enantiomers of rabeprazole than those of lansoprazole.

Biotransformation of pantoprazole by the fungusCunninghamella blakesleeana

To investigate the biotransformation of pantoprazole, a proton-pump inhibitor, by filamentous fungus and further to compare the similarities between microbial transformation and mammalian metabolism of pantoprazole, four strains of Cunninghamella (C. blakesleeana AS 3.153, C. echinulata AS 3.2004, C. elegans AS 3.156, and AS 3.2028) were screened for the ability to catalyze the biotransformation of pantoprazole. Pantoprazole was partially metabolized by four strains of Cunninghamella, and C. blakesleeana AS 3.153 was selected for further investigation. Three metabolites produced by C. blakesleeana AS 3.153 were isolated using semi-preparative HPLC, and their structures were identified by a combination analysis of LC/MS(n) and NMR spectra. Two further metabolites were confirmed with the aid of synthetic reference compounds. The structure of a glucoside was tentatively assigned by its chromatographic behavior and mass spectroscopic data. These six metabolites were separated and quantitatively assayed by liquid chromatography-ion trap mass spectrometry. After 96h of incubation with C. blakesleeana AS 3.153, approximately 92.5% of pantoprazole was metabolized to six metabolites: pantoprazole sulfone (M1, 1.7%), pantoprazole thioether (M2, 12.4%), 6-hydroxy-pantoprazole thioether (M3, 1.3%), 4'-O-demethyl-pantoprazole thioether (M4, 48.1%), pantoprazole thioether-1-N-beta-glucoside (M5, 20.6%), and a glucoside conjugate of pantoprazole thioether (M6, 8.4%). Among them, M5 and M6 are novel metabolites. Four phase I metabolites of pantoprazole produced by C. blakesleeana were essentially similar to those obtained in mammals. C. blakesleeana could be a useful tool for generating the mammalian phase I metabolites of pantoprazole.

Intravenous administration of lansoprazole: a preliminary study of dose ranging and efficacy in upper gastrointestinal bleeding

Using 24-h pH monitoring, we studied the optimal dose and mode of administration of lansoprazole (LAN) injection in healthy adult male volunteers in three tests of antisecretory effect. We followed this with a dose-finding study, using the drug's suppressive effect on increased gastric acid secretion due to surgical stress as the indicator. Finally, we conducted a pilot study to determine the optimal mode of administration and efficacy of the drug in patients with haemorrhage from the upper gastrointestinal tract. Twenty-four-hour intragastric pH monitoring established the order of potency of the different regimens: LAN 30 mg b.d. > LAN 15 mg b.d.; and LAN 30 mg b.d., intravenous drip infusion = LAN 30 mg b.d., bolus injection. Lansoprazole 30 mg b.d. appeared to be slightly more effective than LAN 15 mg b.d. in suppressing increased gastric acid secretion due to post-operative stress and in haemostasis in patients with upper gastrointestinal bleeding. No severe adverse effects were observed in either study.

[Chiral separation of tenatoprazole enantiomers using high performance liquid chromatography on vacomycin-bonded chiral stationary phase]

Vacomycin-bonded chiral stationary phase was used for the direct chiral separation of tenatoprazole enantiomers using reversed-phase high performance liquid chromatography (HPLC). The influences of the kinds and concentration of buffer and organic modifier, the pH value of buffer, column length and column temperature on the separation were examined. The chiral HPLC method for the separation of tenatoprazole enantiomers on a Chirobiotic V column (150 mm x 4.6 mm, 5 microm) was established with simplicity and good reproducibility using 0.02 mol/L ammonium acetate buffer (pH 6.0)-tetrahydrofuran (93:7, v/v) as the mobile phase at a flow rate of 0.5 mL/min and 20 degrees C. Under the above conditions, the enantiomers were separated on baseline with the resolution of 1.68. The relative standard deviations (RSDs) for the retention times of tenatoprazole enantiomers were 0.48% and 0.49% (n = 6). The RSDs for the peak areas of tenatoprazole enantiomers were 0.45% and 0.55% (n = 6).

Genotype 3 hepatitis E has been widespread in pig farms of Shanghai suburbs

Hepatitis E virus (HEV) genotype 3 was first identified in swine raised on a Shanghai suburban pig farm in late 2006. To accurately determine the prevalence of HEV infections among Shanghai pig farms, 426 pig fecal samples were collected from 37 pig farms located in all 10 Shanghai suburban districts and tested for the presence of HEV RNA using RT-PCR. Genetic analysis based on an amplified 150-bp ORF2 fragment revealed 111 samples to be HEV positive, and the prevalence of HEV infection within the different districts varied between 0 and 41.7%. Thirty-two samples were sequenced, and phylogenetic analysis indicated that 10 isolates belonged to HEV genotype 4 and were most closely related to 3 human and 2 swine HEV strains, all of which had originally been isolated from Asian countries including Japan and China. The remaining 22 isolates belonged to genotype 3 and were most closely related to a strain of swine HEV, US-SW, isolated from pigs in the United States. Our data indicated that genotype 3 HEV was widespread among suburban Shanghai pig farms although further study is required to determine the source and zoonotic nature of the virus.

Prediction of gastroesophageal reflux in otitis media with effusion in adults

CONCLUSIONS

The measurement of pepsinogen I (PGI) in middle-ear effusions (MEEs) and a questionnaire on the frequency symptoms of gastroesophageal reflux (GER) disease are tools that can be used to screen for the existence of GER.

OBJECTIVE

To seek methods that would be beneficial as a screen for the presence of GER among adult patients with OME.

MATERIALS AND METHODS

Fifty-eight adult outpatients with OME were asked to answer a questionnaire of the frequency scale for symptoms of GER disease. Samples of MEEs were obtained from each subject and were measured for concentrations of PGI and PGII. Some patients were followed up after being treated with a proton pump inhibitor.

RESULTS

The percentage of patients with high PGI concentrations in their MEEs was higher in those with GER-related symptoms than in those without GER-related symptoms. Moreover, OME was present bilaterally in a higher percentage of patients with GER-related symptoms. There were patients in whom PGI levels decreased after receiving treatment for GER.

Safety of lansoprazole

The care with which patients are monitored during clinical trials provides an excellent database to assess the tolerability and safety of drugs. Additional information can be obtained from knowledge of the compound itself, its metabolism and its pharmacological action. Other compounds from the same class can highlight areas that need particular study. All these factors have been used to assess the safety of lansoprazole. Lansoprazole has been administered to 4749 subjects and has been well tolerated. Only 1.2% of patients have been withdrawn from trials because of suspected drug-related events but there was no pattern and no relationship to drug dosage. Diarrhoea (3.2%) and headache (4.7%) were the most commonly reported adverse events.

Lansoprazole in the treatment of reflux oesophagitis: a survey of clinical studies

The newly developed proton pump inhibitor lansoprazole has been compared to placebo, ranitidine and with omeprazole in a number of clinical studies in patients with reflux oesophagitis. In three comparative studies against ranitidine, lansoprazole was found to be superior in terms of healing rates and symptom relief. In two studies against omeprazole, no significant difference was found in healing rates, while a Scandinavian study demonstrated more prompt relief from heartburn. Further studies are presently being conducted to evaluate the potential of lansoprazole in long-term treatment of reflux oesophagitis. It is concluded that lansoprazole is a safe, effective therapy for reflux oesophagitis, superior to ranitidine and comparable with omeprazole.

An open trial of long-term therapy with lansoprazole in patients with peptic ulceration resistant to extended high-dose ranitidine treatment

Forty-two patients with peptic ulceration of the duodenum, stomach or oesophagus, who had not responded to 3 or more months of high-dose treatment with ranitidine (450 or 600 mg/day), were treated with oral lansoprazole at 30-60 mg daily. In 40 patients (95.2%) the ulcers healed within 2-12 weeks. In the remaining 2 patients healing took several months but eventually all ulcers healed. After healing, 40 patients underwent long-term maintenance treatment with 30-60 mg lansoprazole daily for 1-3 years (continuing). During maintenance therapy with lansoprazole, no endoscopically verified relapses occurred when the drug was taken regularly. In 1 patient treatment had to be discontinued because of a drug-related colitis that disappeared soon after treatment had been stopped. There were no significant changes in routine laboratory tests in any patient. Basal serum gastrin concentrations, which were already elevated by the previous high-dose ranitidine treatment (125 +/- 25 pg/ml), rose to four times the normal values after 4 weeks of treatment with lansoprazole (255 +/- 65 pg/ml). Thereafter no further increases in basal serum gastrin concentrations were observed, even after 3 years of administration. The volume density of argyrophilic cells in the oxyntic mucosa increased slightly during lansoprazole treatment; until now no dysplasia of the enterochromaffin-like cells has been observed. In conclusion, 30-60 mg lansoprazole daily healed ranitidine-resistant peptic ulcers, and subsequent maintenance therapy with 30-60 mg lansoprazole daily was found to be highly effective and safe over the time observed.

Acute treatment of duodenal ulcer: experience with lansoprazole

Clinical experience with lansoprazole in the acute treatment of duodenal ulcer patients has been compared with treatment using placebo, H2-antagonists or omeprazole. Among the various lansoprazole dosage regimens that have been tested, 30 mg daily for 4 weeks appears to be the optimal regimen to relieve pain rapidly and to heal ulceration in up to 90-95% of patients. Lansoprazole tolerability in the short term appears excellent, most adverse effects are trivial and not dose related. Duodenal ulcer relapse after ulcer healing with lansoprazole appears to occur at a rate similar to that observed after treatment with omeprazole or histamine H2-antagonists.

Prospective study of the long-term efficacy and safety of lansoprazole in patients with the Zollinger-Ellison syndrome

The long-term safety and efficacy of lansoprazole were studied in 21 patients with Zollinger-Ellison syndrome. The initial maintenance dose was determined by acid inhibition studies. In all patients lansoprazole controlled gastric acid hypersecretion and peptic symptoms in both the short and long term. Patients were treated for a mean of 31 months (range 1-43 months) with all but 4 patients followed for > 18 months. The mean initial dose was 60 mg/day, with 2 patients requiring a twice daily dose and the others a single daily dose. During long-term treatment 6 patients required an increased dosage, 5 within the first year. Long-term maintenance doses were reduced in 5 of the 6 patients in whom this was attempted. No changes in serum gastrin concentration, haematological parameters, liver function studies or other biochemical parameters occurred due to lansoprazole. No patient developed a gastric carcinoid tumour while being treated with lansoprazole. These results demonstrate that long-term treatment with lansoprazole is both safe and effective in patients with Zollinger-Ellison syndrome, and suggest that this drug will be useful in such patients. Furthermore, maintenance doses of lansoprazole, determined by the currently recommended method of acute acid titration studies in patients with Zollinger-Ellison syndrome, are too high.

Quantification of tenatoprazole in rat plasma by HPLC: validation and its application to pharmacokinetic studies

A simple, reliable HPLC method with UV detection (295 nm) in rat plasma was developed and validated for quantification of tenatoprazole, a novel proton pump inhibitor, which is in clinical trials. Following a single-step liquid-liquid extraction, the analyte and internal standard were separated using an isocratic mobile phase on a reverse phase C(18) column. The lower limit of quantitation was 20 ng/mL, with a relative standard deviation of less than 10%. A linear dynamic range of 20-6000 ng/mL was established. This HPLC method was validated with between-batch and within-batch precision of 2.9-6.3 and 1.4-5.8%, respectively. The between-batch and within-batch accuracy was 95.1-104.1 and 92.4-101.0%, respectively. This validated method is simple and repeatable enough to be used in pharmacokinetic studies.

Factors influencing the shift of patients from one proton pump inhibitor to another: the effect of direct-to-consumer advertising

BACKGROUND

Switching from one proton pump inhibitor (PPI) to another is common, and may be related to factors other than efficacy and tolerability.

OBJECTIVES

The purposes of this study were to describe the incidence of therapeutic switching among PPI users, quantify direct ambulatory medical costs of switching, and characterize the relationship between product switching and variables hypothesized to influence a switch (eg, direct-to-consumer [DTC] advertising, structure of insurance coverage, disease diagnosis).

METHODS

This was a retrospective cohort study of health plans using 1998 data. The subjects were employees and dependents with employer-sponsored health insurance contributing to the Medstat Market-Scan administrative dataset. Using a commercially available database to quantify DTC advertising by marketing area, market-specific expenditures were matched to eligible subjects. Among PPI users, we identified those who switched from one product to another (switchers) and compared their utilization and spending with nonswitchers. We then evaluated the relationship between drug use and variables hypothesized to affect switching: DTC advertising, insurance characteristics, patient diagnosis, diagnostic procedures, comorbidities, age, and sex.

RESULTS

The analysis used data for 396,500 individuals from 47 unique markets that were geographically well distributed, with population density similar to that of the United States overall. The sample was also comparable with US census estimates for age and sex among working adults and their dependents. Only 620 (6.3%) of PPI users switched products during the 1998 calendar year. Annual diagnostic and drug costs were >US $400 higher for switchers than nonswitchers. Subjects in areas with high levels of DTC advertising were 43% more likely to switch from lansoprazole to omeprazole than those in the low-expenditure areas. Additionally, patients paying prescription drug copayments >US $5 were 12% less likely to switch from lansoprazole to omeprazole than patients paying lower copayments.

CONCLUSIONS

In these privately insured patients using PPIs, product switching was associated with increased treatment costs. DTC advertising and patient cost-sharing were important predictors of product switching.

Treatment of laryngopharyngeal reflux improves asthma symptoms in asthmatics

OBJECTIVE

Laryngopharyngeal reflux (LPR) is defined as the movement of gastric content toward laryngopharynx and is a common occurrence in patients with asthma. This study aimed (1) to determine the incidence of LPR in patients with asthma by assessment of symptom scores and indirect laryngoscopy and (2) to determine the effect of LPR treatment on asthma symptom scores.

METHODS

A total of 28 patients with mild to moderate asthma (24 women, 4 men, mean age 46 +/- 6 years) were included in the study, and after all patients completed LPR and asthma symptom questionnaires, indirect videolaryngoscopy was performed. In patients with LPR, daily treatment with 40 mg pantoprazole was administered for 3 months. Symptom score assessment and indirect videolaryngoscopic examination were repeated at the end of treatment.

RESULTS

A diagnosis of LPR was made in 21 of 28 patients (75%) by indirect laryngoscopy. A statistically significant improvement was observed in asthma and LPR symptoms in patients with LPR after the treatment (p = 0.001 and p < 0.001, respectively).

CONCLUSIONS

LPR is a frequent condition in asthma patients. When the LPR symptom questionnaire and indirect laryngoscopy findings are suggestive of LPR, treatment with a proton pump inhibitor provides improvement in both asthma and LPR symptoms.

The role of proton-pump inhibitor therapy in patients with gastroesophageal reflux disease and difficult-to-control asthma

Difficult-to-control asthma is a frustratingly difficult condition to treat. Many factors contribute to this condition, including gastroesophageal reflux disease. Response to potent acid suppressive therapy with proton-pump inhibitors is less than universal or complete, and underlines the multifactorial nature of the disease. However, the authors of this paper feel strongly that, whereas gastroesophageal reflux disease can be reliably identified, patients with difficult-to-control asthma will experience an improvement in symptoms when treated with acid-suppressive therapy, while bearing in mind that other contributory factors may have to be eliminated at the same time.

Effects of rabeprazole or famotidine during cardiac surgery on perioperative gastric and esophageal pH readings

OBJECTIVES

Upper gastrointestinal bleeding, particularly from a stress-induced duodenal ulcer, is an extremely important perioperative complication in cardiovascular surgery.

METHODS

In the present study, 33 patients undergoing elective open heart surgery between July 2000 and February 2001 were allocated to either a famotidine (FAM) or rabeprazole (RPZ) group to examine the perioperative gastric and esophageal pH readings, in conjunction with an investigation into the effect of infection with Helicobacter pylori (HP).

RESULTS

Postoperative upper gastrointestinal bleeding did not occur in either group, and the intraoperative and postoperative mean gastric pH readings, as well as the holding time pH>6, suggested sufficient acid suppression by either drug. Gastric acid secretion was less strongly suppressed in HP-negative patients in the FAM group, but was unaffected by HP infection status in the RPZ group.

CONCLUSION

The FAM group and RPZ group revealed a sufficient effect of gastric acid suppression. It was indicated that FAM had an insufficient effect of gastric acid suppression for HP-negative patients.

Endoplasmic reticulum stress response is involved in the pathogenesis of stress induced gastric lesions in rats

Stress gastric ulcer is a serious complication, but the mechanism involved is not fully clarified. It is well known that mucosal cell apoptosis plays a crucial role in the pathogenesis of gastric ulceration. Recent studies have shown that endoplasmic reticulum (ER) stress is an important pathway leading to cellular apoptosis. To investigate the role of ER stress in the pathogenesis of stress gastric ulcer, we studied the alteration in the expression of ER stress markers GRP78 (glucose-regulated protein 78) and caspase-12 (an ER stress-specific proapoptotic molecule) and their relations with gastric mucosal apoptosis during development of stress gastric lesions in the water-immersion and restraint stress (WRS) model in rats. Rats developed severe gastric lesions after 6 h of WRS. Typical apoptosis was observed at the edge cells of WRS induced gastric lesions. Western blot analysis showed that GRP78 and activated caspase-12 were over-expressed in the gastric tissues of WRS rats. Immunohistochemical analysis demonstrated that increased GRP78 and caspase-12 were distributed only under the lesions. In addition, dithiothreitol and tunicamycin (ER stress inducers), which increased the expression of GRP78 and activated caspase-12, caused gastric mucosal injury and mucosal cell apoptosis in vitro. These findings suggest that ER stress might be involved in the development of stress gastric ulcer through an apoptotic mechanism.

Intragastric acidity after switching from 5-day treatment with intravenous pantoprazole 40 mg/d to 5-day treatment with oral esomeprazole 40 mg/d or pantoprazole 40 mg/d: an open-label crossover study in healthy adult volunteers

BACKGROUND

After a course of IV proton pump inhibitor therapy, patients might require continued oral antisecretory therapy. A direct comparison of therapeutic alternatives could assist physicians in decisions regarding optimal acid-suppressive therapy. Oral esomeprazole might control intragastric acidity more effectively compared with other acid-suppressive agents after IV therapy.

OBJECTIVE

The aim of this study was to compare intragastric acid control on day 5 of administration of esomeprazole magnesium versus pantoprazole 40 mg PO QD after switching from 5 days of treatment with pantoprazole 40 mg IV in healthy volunteers.

METHODS

This randomized, open-label, comparative, 2-way crossover study was conducted at the Oklahoma Foundation for Digestive Research, Oklahoma City, Oklahoma, between October and December 2004. Healthy, Helicobacter pylori-negative adults were randomly assigned to 1 of 2 dosing sequences: pantoprazole IV followed by esomeprazole PO or pantoprazole IV followed by pantoprazole PO. All study medications were administered for 5 days at a dose of 40 mg QD. IV pantoprazole was administered over 2 minutes; all medications were administered 30 minutes before breakfast. There was a 10- to 21-day washout period between each 10-day dosing period. All doses were administered at the study site. Before oral study drug administration on days 1 and 5, 24-hour pH monitoring was performed using a pH catheter positioned 10 cm distal to the lower esophageal sphincter in the stomach. The primary end point was percentage of time with pH >4 (%t pH >4) during the 24-hour pH-monitoring period. Tolerability was assessed using spontaneous reporting, laboratory analysis, and vital-sign measurement.

RESULTS

Of 42 subjects randomized to treatment sequences, 4 were withdrawn during the study because of invalid pH data; 38 subjects (24 men, 14 women; mean [SD] age, 25.2 [8.1] years) had assessable data. Day-5 %t pH >4 was 68.5% with esomeprazole and 53.3% with pantoprazole (P < 0.001). Day-1 %t pH >4 was 62.5% with esomeprazole and 51.0% with pantoprazole (P < 0.001). The most common adverse events were rhinitis (2 subjects each with pantoprazole IV and PO; 1 subject with esomeprazole) and headache (2 subjects with esomeprazole; 1 subject with pantoprazole IV).

CONCLUSIONS

The results of this study in healthy adult volunteers suggest that switching from pantoprazole 40 mg IV to esomeprazole 40 mg PO QD more effectively suppresses intragastric acid compared with switching from pantoprazole 40 mg IV to pantoprazole 40 mg PO QD. All 3 treatments were well tolerated.

Intravenous pantoprazole as initial treatment in patients with gastroesophageal reflux disease and a history of erosive esophagitis: a randomized clinical trial

We sought to evaluate safety and efficacy of IV pantoprazole when used as initial therapy in patients with gastroesophageal reflux disease (GERD) and a history of erosive esophagitis (EE) in a double-blind, placebo-controlled, randomized, parallel-group study. Patients were randomized to 7 days of once-daily IV or oral pantoprazole (40 mg) or placebo. Efficacy variables included maximal acid output, basal acid output, and changes from baseline in frequency/severity of GERD symptoms, and frequency of antacid usage. Seventy-eight patients were randomized (n=26/27/25 [IV/oral/placebo]). Mean maximal acid output was 8.4, 6.3, and 20.9 mEq/h for IV or oral pantoprazole, and placebo, respectively. For pantoprazole versus placebo, maximal and basal acid output were significantly lower (P<.001) and there was a numerical trend toward improved GERD and antacid usage. Both treatments were well tolerated. In conclusion, IV/oral pantoprazole were similarly effective in suppressing basal and pentagastrin-stimulated gastric acid secretion in GERD patients with a history of EE.

Inhibition of atazanavir oral absorption by lansoprazole gastric acid suppression in healthy volunteers

STUDY OBJECTIVE

To determine whether the pharmacokinetics of atazanavir, a protease inhibitor used to treat human immunodeficiency virus (HIV) infection, are altered by its coadministration with lansoprazole, a proton pump inhibitor.

DESIGN

Single-dose, open-label, complete-crossover study.

SETTING

Clinical research center.

SUBJECTS

Ten healthy adult volunteers.

MEASUREMENTS AND MAIN RESULTS

In phase A, subjects received a single oral dose of atazanavir 400 mg alone. In phase B, the same subjects received oral lansoprazole 60 mg, and after 24 hours they were given a second dose of oral lansoprazole 60 mg with atazanavir 400 mg. Eleven blood samples were collected from each subject over a 24-hour period for determination of atazanavir plasma concentrations by a validated high-performance liquid chromatography assay. Pharmacokinetic analysis was performed by standard noncompartmental methods. Nine subjects completed the study, and no significant adverse events were reported. Absorption of atazanavir was significantly reduced when it was coadministered with lansoprazole, as evidenced by a 94% decline in mean area under the concentration-time curve during the 24 hours after administration (AUC(0-24)) (p<0.01). The mean +/- SD AUC(0-24) for phase A was 16.3 +/- 9.0 microM x hour versus 0.95 +/- 1.8 microM x hour for phase B (p<0.01). The mean +/- SD maximum concentration of atazanavir was 3.2 +/- 1.7 microM for phase A and 0.13 +/- 0.19 microM for phase B (p<0.01).

CONCLUSION

Acid suppression markedly reduced the bioavailability of atazanavir in this group of healthy volunteers. Based on these results, atazanavir should not be coadministered with lansoprazole or other proton pump inhibitors.

Different effects of fluvoxamine on rabeprazole pharmacokinetics in relation to CYP2C19 genotype status

AIMS

Rabeprazole is known to be a substrate of CYP2C19. Our objective was to evaluate the possible effect of an inhibitor of CYP2C19, fluvoxamine, and compare the inhibitory effect of fluvoxamine on the metabolism of rabeprazole between CYP2C19 genotypes.

METHODS

A two-way randomized double-blind, placebo-controlled crossover study was performed. Twenty-one volunteers, of whom seven were homozygous extensive metabolizers (EMs), eight were heterozygous EMs and six were poor metabolizers (PMs) for CYP2C19, received two 6-day courses of either fluvoxamine 50 mg or placebo daily in a randomized fashion with a single oral dose of rabeprazole 20 mg on day 6 in all cases. Plasma concentrations of rabeprazole and its metabolite rabeprazole thioether were monitored up to 24 h after dosing.

RESULTS

During placebo administration, the mean AUCs(0,infinity) of rabeprazole in homozygous EMs, heterozygous EMs and PMs were 882 (95% CI, 602, 1162) ng ml-1h , 1214 (975, 1453) ng ml-1 h and 2762 (2482, 3042) ng ml-1 h (P<0.001), respectively. Fluvoxamine treatment increased AUC(0,infinity) of rabeprazole and rabeprazole thioether by 2.8-fold (P<0.001) and 5.1-fold (P<0.01) in homozygous EMs, and by 1.7-fold (P<0.01) and 2.6-fold (P<0.01) in heterozygous EMs, and significantly prolonged the elimination half-life of rabeprazole and rabeprazole thioether in homozygous EMs and in heterozygous EMs, whereas no difference in any pharmacokinetic parameters was found in PMs. There was a significant difference in fluvoxamine-mediated percentage increase in AUC(0,infinity) of rabeprazole and rabeprazole thioether between CYP2C19 genotypes.

CONCLUSIONS

The present study indicates that there are significant drug interactions between rabeprazole and fluvoxamine in EMs of CYP2C19. It is predominantly involved in rabeprazole and rabeprazole thioether metabolism in EMs. Therefore, CYP2C19 is the key determinant of rabeprazole disposition in EMs.