Transcriptomic analysis reveals the molecular basis of photoperiod-regulated sex differentiation in tropical pumpkins (Cucurbita moschata Duch.).

BACKGROUND: Photoperiod, or the length of the day, has a significant impact on the flowering and sex differentiation of photoperiod-sensitive crops. The "miben" pumpkin (the main type of Cucurbita moschata Duch.) is well-known for its high yield and strong disease resistance. However, its cultivation has been limited due to its sensitivity to photoperiod. This sensitivity imposes challenges on its widespread cultivation and may result in suboptimal yields in regions with specific daylength conditions. As a consequence, efforts are being made to explore potential strategies or breeding techniques to enhance its adaptability to a broader range of photoperiods, thus unlocking its full cultivation potential and further promoting its valuable traits in agriculture. RESULTS: This study aimed to identify photoperiod-insensitive germplasm exhibiting no difference in sex differentiation under different day-length conditions. The investigation involved a phenotypic analysis of photoperiod-sensitive (PPS) and photoperiod-insensitive (PPIS) pumpkin materials exposed to different day lengths, including long days (LDs) and short days (SDs). The results revealed that female flower differentiation was significantly inhibited in PPS_LD, while no differences were observed in the other three groups (PPS_SD, PPIS_LD, and PPIS_SD). Transcriptome analysis was carried out for these four groups to explore the main-effect genes of sex differentiation responsive to photoperiod. The main-effect gene subclusters were identified based on the principal component and hierarchical cluster analyses. Further, functional annotations and enrichment analysis revealed significant upregulation of photoreceptors (CmCRY1, F-box/kelch-repeat protein), circadian rhythm-related genes (CmGI, CmPRR9, etc.), and CONSTANS (CO) in PPS_LD. Conversely, a significant downregulation was observed in most Nuclear Factor Y (NF-Y) transcription factors. Regarding the gibberellic acid (GA) signal transduction pathway, positive regulators of GA signaling (CmSCL3, CmSCL13, and so forth) displayed higher expression levels, while the negative regulators of GA signaling, CmGAI, exhibited lower expression levels in PPS_LD. Notably, this effect was not observed in the synthetic pathway genes. Furthermore, genes associated with ethylene synthesis and signal transduction (CmACO3, CmACO1, CmERF118, CmERF118-like1,2, CmWIN1-like, and CmRAP2-7-like) showed significant downregulation. CONCLUSIONS: This study offered a crucial theoretical and genetic basis for understanding how photoperiod influences the mechanism of female flower differentiation in pumpkins.

Combined contributions of cytochrome P450s (CYPs) and non-enzymatic metabolism in the in vitro biotransformation of anaprazole, a novel proton pump inhibitor.

Anaprazole, a new proton pump inhibitor (PPI), is designed for the treatment of acid-related diseases, such as gastric ulcers and gastroesophageal reflux. This study explored the in vitro metabolic transformation of anaprazole. The metabolic stabilities of anaprazole in human plasma and human liver microsomes (HLM) were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Then, the contribution (%) of non-enzymatic and cytochrome P450s (CYPs) enzyme-mediated anaprazole metabolism was assessed. To obtain the metabolic pathways of anaprazole, the metabolites generated in HLM, thermal deactivated HLM, and cDNA-expressed recombinant CYPs incubation systems were identified by ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UPLC/Q-TOF-MS). Results showed that anaprazole was very stable in human plasma and unstable in HLM. The contribution (%) of non-enzymatic vs. CYPs enzyme-mediated metabolism was 49% vs. 51%. CYP3A4 was the major enzyme (48.3%), followed by CYP2C9 (17.7%) and CYP2C8 (12.3%), in responsible for the metabolism of anaprazole. Specific chemical inhibitors targeting CYP enzymes notably blocked the metabolic transformation of anaprazole. Six metabolites of anaprazole were identified in the non-enzymatic system, whereas 17 metabolites were generated in HLM. The biotransformation reactions mainly included sulfoxide reduction to thioether, sulfoxide oxidation to sulfone, deoxidation, dehydrogenation, O-dealkylation or O-demethylation of thioether, O-demethylation and dehydrogenation of thioether, O-dealkylation and dehydrogenation of thioether, thioether O-dealkylation and dehydrogenation of thioether, and O-dealkylation of sulfone. Both enzymatic and non-enzymatic metabolisms contribute to the clearance of anaprazole in human. Anaprazole is less likely to develop drug-drug interactions in clinical use compared to other PPIs.

Esomeprazole induces structural changes and apoptosis and alters function of in vitro canine neoplastic mast cells.

Histamine-2 receptor antagonists such as famotidine and proton pump inhibitors such as esomeprazole are commonly used in canine MCT disease, but direct effects on dog MCs have not been evaluated. Omeprazole is a proton pump inhibitor which has been demonstrated to cause structural and functional changes to in vitro murine mast cells (MCs). It has not yet been determined if esomeprazole, the commercially available and commonly prescribed S-isomer of omeprazole, has similar effects. Our primary study objective was to evaluate and compare the effects of acid suppressants (esomeprazole and famotidine) on MC ultrastructure, viability, and function in vitro using both healthy and neoplastic MCs. Murine bone marrow derived mast cells (BMMC), human LAD2, and canine C2 and BR cells, were used for these studies, representing a single healthy (i.e., BMMCs) MC model and multiple neoplastic MC models (i.e., LAD2, C2, BR), respectively. The rat basophilic leukemic (RBL-2H3) and canine B cell lymphoma 17-71 cell lines served as granulocytic and agranulocytic control lines for experiments, respectively. The treatment effect of acid suppressants on MC ultrastructure was assessed via both light and transmission electron microscopy. Differences in MC viability was assessed between groups via MTS-based, colorimetric assays and flow cytometry. Degranulation was assessed by quantification of ß-hexosaminidase (i.e., LAD2 and RBL-2H3). Esomeprazole-treated MCs of all lines exhibited dramatic time and concentration-dependent alterations in ultrastructure (i.e., increased vacuolization, compromise of cell membrane), increased apoptosis, and altered degranulation responses in comparison to famotidine and vehicle-treated cells. The canine B cell lymphoma cells consistently exhibited either no significant (i.e., cytotoxicity assays) or greatly diminished treatment responses (i.e., apoptosis) compared to MCs. Esomeprazole, but not famotidine, induces significant cytotoxicity, as well as alterations to cell structure and function to multiple lines of in vitro neoplastic MCs. Continued in vitro work investigating the specific mechanisms by which proton pump inhibitors induce these effects, as well as prospective, in vivo work comparing the treatment effects of acid suppressants on canine MCTs, are warranted.

Evidence for Metabolic Activation of Omeprazole In Vitro and In Vivo.

Omeprazole (OPZ) is a proton pump inhibitor commonly used for the treatment of gastric acid hypersecretion. Studies have revealed that use of OPZ can induce hepatotoxicity, but the mechanisms by which it induces liver injury are unclear. This study aimed to identify reactive metabolites of OPZ, determine the pathways of the metabolic activation, and define the correlation of the bioactivation with OPZ cytotoxicity. Quinone imine-derived glutathione (GSH), N-acetylcysteine (NAC), and cysteine (Cys) conjugates were detected in OPZ-fortified rat and human liver microsomal incubations captured with GSH, NAC, or Cys. The same GSH conjugates were detected in bile of rats and cultured liver primary cells after exposure to OPZ. Similarly, the same NAC conjugates were detected in urine of OPZ-treated rats. The resulting quinone imine was found to react with Cys residues of hepatic protein. CYP3A4 dominated the metabolic activation of OPZ. Exposure to OPZ resulted in decreased cell survival in cultured primary hepatocytes. Pretreatment with ketoconazole attenuated the susceptibility of hepatocytes to the cytotoxicity of OPZ.

Structural Basis for Binding of Potassium-Competitive Acid Blockers to the Gastric Proton Pump.

As specific inhibitors of the gastric proton pump, responsible for gastric acidification, K+-competitive acid blockers (P-CABs) have recently been utilized in the clinical treatment of gastric acid-related diseases in Asia. However, as these compounds have been developed based on phenotypic screening, their detailed binding poses are unknown. We show crystal and cryo-EM structures of the gastric proton pump in complex with four different P-CABs, tegoprazan, soraprazan, PF-03716556 and revaprazan, at resolutions reaching 2.8 Å. The structures describe molecular details of their interactions and are supported by functional analyses of mutations and molecular dynamics simulations. We reveal that revaprazan has a novel binding mode in which its tetrahydroisoquinoline moiety binds deep in the cation transport conduit. The mechanism of action of these P-CABs can now be evaluated at the molecular level, which will facilitate the rational development and improvement of currently available P-CABs to provide better treatment of acid-related gastrointestinal diseases.

Tumor-derived exosomes co-delivering aggregation-induced emission luminogens and proton pump inhibitors for tumor glutamine starvation therapy and enhanced type-I photodynamic therapy.

Although promising, the efficiency of aggregation-induced emission luminogens (AIEgens)-based photodynamic therapy (PDT) is limited by cellular glutathione (GSH). GSH is not a terminal reducing agent but it can be oxidized and subsequently reduced to its original state by reductases to further participate in antioxidant activity. It is therefore imperative to control GSH for effectively inducing oxidation within tumor cells. Recent studies showed that tumor cell metabolism depends mainly on glutamine, which is also the nitrogen and ATP source for GSH synthesis. Therefore, glutamine-based starvation therapy may be effective in enhancing photodynamic therapy. In this work, tumor-derived exosomes were developed for co-delivering AIEgens and proton pump inhibitors (PPI) for tumor combination therapy. Tumor-derived exosomes could specifically deliver drugs to the tumor sites, where PPI inhibited cell glutamine metabolism, suppressed tumor cell GSH and ATP production, and improved the effect of type-I PDT from AIEgens. When used in the treatment of MGC803 gastric cancer subcutaneous model, our system shows a high tumor growth inhibition rate, and even promoting tumor immunogenic death. This is the first work which combine inhibition of glutamine metabolism with PDT, and it has the potential to be applied for future designs of new tumor metabolic therapies and photodynamic systems.

Nano-Enabled Reposition of Proton Pump Inhibitors for TLR Inhibition: Toward A New Targeted Nanotherapy for Acute Lung Injury.

Toll-like receptor (TLR) activation in macrophages plays a critical role in the pathogenesis of acute lung injury (ALI). While TLR inhibition is a promising strategy to control the overwhelming inflammation in ALI, there still lacks effective TLR inhibitors for clinical uses to date. A unique class of peptide-coated gold nanoparticles (GNPs) is previously discovered, which effectively inhibited TLR signaling and protected mice from lipopolysaccharide (LPS)-induced ALI. To fast translate such a discovery into potential clinical applicable nanotherapeutics, herein an elegant strategy of "nano-enabled drug repurposing" with "nano-targeting" is introduced to empower the existing drugs for new uses. Combining transcriptome sequencing with Connectivity Map analysis, it is identified that the proton pump inhibitors (PPIs) share similar mechanisms of action to the discovered GNP-based TLR inhibitor. It is confirmed that PPIs (including omeprazole) do inhibit endosomal TLR signaling and inflammatory responses in macrophages and human peripheral blood mononuclear cells, and exhibits anti-inflammatory activity in an LPS-induced ALI mouse model. The omeprazole is then formulated into a nanoform with liposomes to enhance its macrophage targeting ability and the therapeutic efficacy in vivo. This research provides a new translational strategy of nano-enabled drug repurposing to translate bioactive nanoparticles into clinically used drugs and targeted nano-therapeutics for ALI.

An analysis of the biopharmaceutical behaviour of proton pump inhibitors with different physicochemical properties.

At present, little information on the biopharmaceutical behaviour of proton pump inhibitors (PPIs) describing their absorption and biodistribution in vivo has been reported because the extreme instability of PPIs in the gastrointestinal environment makes it difficult to analyze such behaviour. In this work, a modified rat in situ intestinal perfusion model was employed to investigate absorption in the gastrointestinal tract and subsequent biodistribution of several PPIs (ilaprazole, esomeprazole and rabeprazole), which have different physicochemical properties. Our data indicated that PPIs exhibited significantly enhanced absorption rates in the whole intestine, including the duodenum, jejunum, ileum and colon, corresponding to the increase in the oil-water partition coefficient (LogP). PPIs and corresponding salt types showed no obvious differences in absorption, implying that solubility changes in the PPI have little effect on its absorption in the gastrointestinal tract. Among these PPIs, ilaprazole presented a more stable intestinal absorption behaviour, as well as more distribution and longer residence time in the stomach by HPLC-MS/MS analysis and radioactivity counts after 14C radiolabelling. These results may be useful information for PPI optimization and oral formulation design.

Association between migraine prevalence, treatment with proton-pump inhibitors and CYP2C19 phenotypes in UK Biobank.

Proton-pump inhibitors (PPIs) are used to suppress gastric acid secretion in several gastrointestinal conditions. While these drugs are generally well tolerated, their long-term use may be associated with different adverse effects, including migraine. We analyzed the association between treatment with PPIs (omeprazole, esomeprazole, lansoprazole, pantoprazole and rabeprazole) and migraine prevalence in the UK Biobank cohort through a cross-sectional analysis (using baseline data for 468,280 participants, 16,390 of whom had migraine) and a longitudinal analysis (including 145,007 participants with no migraine at baseline, of whom 3786 had probable migraine without aura [MWOA] and 9981 probable migraine with aura [MWA] or both MWOA and MWA at an average follow-up time of 10.06 years). We also evaluated the modulating role of the metabolizer phenotype of CYP2C19, the major enzyme involved in PPI clearance. Treatment with PPIs was associated with higher migraine prevalence at baseline (odds ratio [OR] = 1.25, p < 0.0001). CYP2C19 rapid metabolizer phenotype was associated with lower prevalence of migraine exclusively in participants treated with PPIs (OR = 0.89, p = 0.029). In addition, treatment with PPIs was associated with higher incidence of both probable MWOA (OR = 1.24, p = 0.002) and MWA (OR = 1.43, p < 0.0001) at follow-up. Treatment with PPIs and CYP2C19 poor metabolizer status were associated with higher incidence of probable chronic migraine exclusively in men. Our results suggest a significant association between treatment with PPIs and migraine in this large population-based cohort and support a potential relevant role of gender and CYP2C19 phenotype.

Effects of the Long-term Treatment of Proton Pump Inhibitors on the Function of Kidney and Liver in Laboratory Female Rats.

Proton pump inhibitors (PPIs) are a group of medications effectively used to inhibit gastric acid secretion and to treat many acid-related disorders, including gastroesophageal reflux disease and other gastric disorders. Recent studies recommended that they may be associated with the risk of chronic kidney disease and liver disease. Therefore, the current study aimed to investigate the effect of long-term treatment with PPIs on kidney and liver function in laboratory rats. Fifteen female albino white rats (Rattusnorvigicus) were randomly assigned to three groups of five animals. The control group was fed regular pellet, group PPI-2 received standard pellet diet and was given esomeprazole (10 mg/kg b.w.) via daily oral gavage in mornings for two weeks, and group PPI-3 was fed standard pellet diet and was given esomeprazole (10 mg/kg b.w.) via daily oral gavage in mornings for three months. Blood samples were taken after 2 weeks and 3 months by cardiac puncture for measuring serum creatinine, urea, total bilirubin, alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP). In addition, kidney and liver tissues were histopathologically evaluated. Serum creatinine, urea, ALT, total bilirubin, and ALP significantly increased in group PPI-3, compared to other groups. Histopathological study of the kidneys and liver revealed normal histology structure in the control group and the rats of the PPI-2 group, while some histological changes were observed in the liver and kidney of the animals in the PPI-3 group. The histological changes included the widening of Bowman's space and shrunken glomeruli, whereas the renal tubules had congested tubular cells. Furthermore, congestion in the blood vessels and hepatic cells degradation were observed in the liver. These data indicate that the long-term administration of PPIs has adverse effects on the structure and function of the kidney and liver.

Measuring dissolution profiles of single controlled-release drug pellets.

Many solid-dose oral drug products are engineered to release their active ingredients into the body at a certain rate. Techniques for measuring the dissolution or degradation of a drug product in vitro play a crucial role in predicting how a drug product will perform in vivo. However, existing techniques are often labor-intensive, time-consuming, irreproducible, require specialized analytical equipment, and provide only "snapshots" of drug dissolution every few minutes. These limitations make it difficult for pharmaceutical companies to obtain full dissolution profiles for drug products in a variety of different conditions, as recommended by the US Food and Drug Administration. Additionally, for drug dosage forms containing multiple controlled-release pellets, particles, beads, granules, etc. in a single capsule or tablet, measurements of the dissolution of the entire multi-particle capsule or tablet are incapable of detecting pellet-to-pellet variations in controlled release behavior. In this work, we demonstrate a simple and fully-automated technique for obtaining dissolution profiles from single controlled-release pellets. We accomplished this by inverting the drug dissolution problem: instead of measuring the increase in the concentration of drug compounds in the solution during dissolution (as is commonly done), we monitor the decrease in the buoyant mass of the solid controlled-release pellet as it dissolves. We weigh single controlled-release pellets in fluid using a vibrating tube sensor, a piece of glass tubing bent into a tuning-fork shape and filled with any desired fluid. An electronic circuit keeps the glass tube vibrating at its resonance frequency, which is inversely proportional to the mass of the tube and its contents. When a pellet flows through the tube, the resonance frequency briefly changes by an amount that is inversely proportional to the buoyant mass of the pellet. By passing the pellet back-and-forth through the vibrating tube sensor, we can monitor its mass as it degrades or dissolves, with high temporal resolution (measurements every few seconds) and mass resolution (700 nanogram resolution). As a proof-of-concept, we used this technique to measure the single-pellet dissolution profiles of several commercial controlled-release proton pump inhibitors in simulated stomach and intestinal contents, as well as comparing name-brand and generic formulations of the same drug. In each case, vibrating tube sensor data revealed significantly different dissolution profiles for the different drugs, and in some cases our method also revealed differences between different pellets from the same drug product. By measuring any controlled-release pellets, particles, beads, or granules in any physiologically-relevant environment in a fully-automated fashion, this method can augment and potentially replace current dissolution tests and support product development and quality assurance in the pharmaceutical industry.

Binding of omeprazole to protein targets identified by monoclonal antibodies.

Omeprazole is the most commonly used proton pump inhibitor (PPI), a class of medications whose therapeutic mechanism of action involves formation of a disulfide linkage to cysteine residues in the H+/K+ ATPase pump on gastric secretory cells. Covalent linkage between the sole sulfur group of omeprazole and selected cysteine residues of the pump protein results in inhibition of acid secretion in the stomach, an effect that ameliorates gastroesophageal reflux and peptic ulcer disease. PPIs, though useful for specific conditions when used transiently, are associated with diverse untoward effects when used long term. The mechanisms underlying these potential off-target effects remain unclear. PPIs may, in fact, interact with non-canonical target proteins (non-pump molecules) resulting in unexpected pathophysiological effects, but few studies describe off-target PPI binding. Here, we describe successful cloning of monoclonal antibodies against protein-bound omeprazole. We developed and used monoclonal antibodies to characterize the protein target range of omeprazole, stability of omeprazole-bound proteins, and the involvement of cysteines in binding of omeprazole to targets. We demonstrate that a wide range of diverse proteins are targeted by omeprazole. Protein complexes, detected by Western blotting, are resistant to heat, detergents, and reducing agents. Reaction of omeprazole occurs with cysteine-free proteins, is not fully inhibited by cysteine alkylation, occurs at neutral pH, and induces protein multimerization. At least two other clinically used PPIs, rabeprazole and tenatoprazole, are capable of binding to proteins in a similar fashion. We conclude that omeprazole binds to multiple proteins and is capable of forming highly stable complexes that are not dependent on disulfide linkages between the drug and protein targets. Further studies made possible by these antibodies may shed light on whether PPI-protein complexes underlie off-target untoward effects of chronic PPI use.

Esomeprazole reduces sperm motility index by targeting the spermic cholinergic machinery: A mechanistic study for the association between use of proton pump inhibitors and reduced sperm motility index.

Recent studies have linked prolonged use of the most commonly prescribed proton pump inhibitors (PPIs) with declined human sperm function and infertility. Here, we report for the first time the most plausible underlying mechanism for this unwarranted secondary mode of action. We followed up on a recent serendipitous discovery in our laboratory regarding PPIs' off-target action and performed detailed pharmacodynamic analyses by combining in silico and in vitro studies to determine the off-target effect of one of the most commonly used PPI, esomeprazole, on the key human acetylcholine biosynthesizing enzyme, choline acetyltransferase (ChAT; EC 2.3.1.6). A pivotal enzyme in the spermic cholinergic system that governs the sperm motility, concentration and quality. Our results were conclusive and showed that both the racemic form, omeprazole and its pure S-enantiomer, esomeprazole, acted as potent mixed-competitive inhibitor of human ChAT with a global inhibition constant (Ki) of 88 nM (95%CI: 10-167 nM) for esomeprazole and 178 nM (95%CI: 140-230 nM) for the racemic drug omeprazole. Most importantly, esomeprazole substantially reduces both total number of motile sperm (by 36%, p < 0.001; and 21% p < 0.0001, at 10 and 100 nM, respectively) as well as the total number of sperm with progressive motility (by 42% p < 0.0016 and by 26% p < 0.0001, respectively) after 60 min relative to 20 min incubation in our ex vivo functional assay performed on ejaculated human sperm. In conclusion, this study presents a completely new perspective regarding PPIs secondary mode of action/unwarranted side effects and calls for further mechanistic and larger clinical studies to elucidate the role of PPIs in infertility.

Qualitative and quantitative determination of anaprazole and its major metabolites in human plasma.

Anaprazole is a novel proton pump inhibitor under development for the treatment of gastric and duodenal ulcers. In the present study, an ultra-performance liquid chromatography-ultraviolet detector/quadrupole time-of-flight mass spectrometry method was developed for the metabolic profiling of human plasma after an oral administration of 40 mg anaprazole. The principal metabolic pathways were identified as sulfoxide reduction to thioether (M8-1), dehydrogenation (M21-1), sulfoxide oxidation to sulfone (M16-3), and sulfoxide reduction with O-demethylation to form carboxylic acid (M7-1). Anaprazole, M8-1, M16-3, M21-1, and M7-1 were selected and further quantified in human plasma by using a rapid and sensitive liquid chromatography-tandem mass spectrometry method. Anaprazole and its four metabolites were extracted from 50 of µL plasma by acetonitrile protein precipitation. Chromatographic retention and separation were achieved on an Kinetex XB-C18 column (50 mm × 4.6 mm i.d., 5 µm) under gradient elution using 5 mM ammonium acetate with 0.005 % ammonium hydroxide and methanol with 0.005 % ammonium hydroxide as the mobile phase. Positive electrospray ionization was performed using multiple reaction monitoring with transitions of m/z 402.2→242.2, 386.2→226.2, 400.2→242.2, 418.2→282.2, and 386.2→161.2 for anaprazole, M8-1, M21-1, M16-3, and M7-1, respectively. This method was linear in the range of 5.00-3000 ng/mL for anaprazole and 1.00-600 ng/mL for the four metabolites. The lower limit of quantitation was established at 5.00 ng/mL for anaprazole and 1.00 ng/mL for the metabolites. The quantitative method was used to evaluate the pharmacokinetics of anaprazole in phase I clinical trials.

Effect of proton pump inhibitors on high-dose methotrexate elimination: a systematic review and meta-analysis.

Background Drug interaction is one factor which may influence high-dose methotrexate (MTX) elimination. Proton pump inhibitors are commonly used as an adjuvant drugs in chemotherapy. However, the effect of proton pump inhibitors on high-dose MTX elimination is currently controversial. Objective To perform a systematic review and meta-analysis to assess the association between co-administration of proton pump inhibitors with plasma MTX concentration and delayed MTX elimination. Setting The Hospital of Kunming Medical University, China. Method We followed the PRISMA guidelines in this meta-analysis and systemic review. We searched PubMed, the Cochrane Database, Embase, the WHO International Clinical Trials Registry Platform, the Wanfang database, the Chinese National Knowledge Infrastructure, the VIP database and the Chinese BioMedical Literature Database. Main outcome measure The main outcome measures are: (1) the plasma MTX concentration at 24 h, 48 h and 72 h.; (2) the frequency of patients with delayed MTX elimination. Results Ten retrospective cohort studies were included in the meta-analysis, with a total of 2760 cycles of high-dose MTX treatment. A meta-analysis revealed that compared to patients who did not receive proton pump inhibitors, patients who received proton pump inhibitors had a significantly higher plasma MTX concentration at 24 h (mean difference 2.71 µM, 95% confidence interval 0.55 to 4.87; p = 0.01) and at 48 h (mean difference 0.14 µM, 95% confidence interval 0.06 to 0.21; p < 0.01) after the MTX infusion. Furthermore, delayed MTX elimination was more frequent in patients that received PPIs (risk ratio 0.59, 95% confidence interval 0.41 to 0.84; p = 0.004). Conclusion This systematic review and meta-analysis reveals that the co-administration of proton pump inhibitors with methotrexate is associated with delayed high-dose MTX elimination. Proton pump inhibitors should be cautiously given when co-administered with high-dose MTX treatment.

Mechanism of Reductive Metabolism and Chiral Inversion of Proton Pump Inhibitors.

Racemic proton pump inhibitors (PPIs) have been developed into pure enantiomers given superior pharmacokinetic profiles. However, after doses of single enantiomer PPIs, different degrees of chiral inversion were observed. We investigated the relationship between chiral inversion and reductive metabolism of PPIs, as well as the mechanism of reductive metabolism. In liver microsomes and Sprague-Dawley rats, PPI thioethers were stereoselectively oxidized to (R)- and (S)-PPIs, indicating that thioethers could be the intermediates of chiral inversion. By comparing the area under the plasma concentration-time curve ratios of thioether to rabeprazole under different routes of administration and blood sampling site, it was determined that thioether was mainly formed in the liver rather than the intestine. The formation rate of PPI thioethers in liver subcellular fractions was significantly higher than that in buffers. Sulfhydryl-blocking agents, such as N-ethylmaleimide, menadione, and ethacrynic acid, inhibited the reductive metabolism of PPIs in vitro, and their corresponding glutathione conjugates were observed. Similar amounts of thioethers were formed in glutathione solutions as in liver subcellular fractions, indicating that biologic reducing agents, instead of reductases, accelerated the reductive metabolism of PPIs. The reduction rates in glutathione solutions were ordered as follows: rabeprazole > omeprazole > lansoprazole > pantoprazole, which was consistent with the natural bond orbital charges of sulfur atoms in these compounds. In conclusion, PPIs were transformed into thioethers by biologic reducing agents in liver, and thioethers continued to be oxidized to two enantiomers, leading to chiral inversion. Furthermore, inhibiting oxidative metabolism of PPIs enhanced reductive metabolism and chiral inversion.

Prediction of ARA/PPI Drug-Drug Interactions at the Drug Discovery and Development Interface.

Advances in understanding of human disease have prompted the U.S. Food and Drug Administration to classify certain molecules as "break-through therapies," providing an accelerated review that may potentially enhance the quality of patient lives. With this designation come compressed timelines to develop drug products, which are not only suitable for clinic trials but can also be approved and brought to the market rapidly. Early risk identification for decreased oral absorption due to drug-drug interactions with proton pump inhibitors (PPIs) or acid-reducing agents (ARAs) is paramount to an effective drug product development strategy. An early ARA/PPI drug-drug interaction (DDI) risk identification strategy has been developed using physiologically based absorption modeling that readily integrates ADMET predictor generated in silico estimates or measured in vitro solubility, permeability, and ionization constants. Observed or predicted pH-solubility profile data along with pKas and drug dosing parameters were used to calculate a fraction of drug absorbed ratio in absence and presence of ARAs/PPIs. An integrated physiologically based pharmacokinetic absorption model using GastroPlus™ with pKa values fitted to measured pH-solubility profile data along with measured permeability data correctly identified the observed ARA/PPI DDI for 78% (16/22) of the clinical studies. Formulation strategies for compounds with an anticipated pH-mediated DDI risk are presented.

Biotransformation of Ilaprazole in Human Liver Microsomes and Human: Role of CYP3A4 in Ilaprazole Clearance and Drug-Drug Interaction.

Ilaprazole is a new proton pump inhibitor and is currently marketed in China and South Korea for the treatment of gastric and duodenal ulcer. Ilaprazole has a favorable long half-life and minimal pharmacokinetic variability associated with CYP2C19 polymorphism. Sulfoxide oxidation of ilaprazole is catalyzed mainly by CYP3A4. Thus, it has been widely accepted that CYP3A4 plays a major role in the clearance of ilaprazole in humans. However, absorption, distribution, metabolism, and excretion data of radiolabeled ilaprazole in humans are not available. The primary goal of this study was to determine if sulfoxide oxidation is a major metabolic pathway of ilaprazole in humans. Metabolite profiles of ilaprazole, ilaprazole sulfide, and ilaprazole sulfone in human liver microsomes (HLMs) were characterized and quantitively analyzed by liquid chromatography (LC)/UV/high-resolution mass spectrometry (HRMS). Moreover, metabolites of ilaprazole in human urine and feces were detected and identified by LC-HRMS. The results revealed that sulfoxide reduction to ilaprazole sulfide rather than sulfoxide oxidation was the major biotransformation pathway in HLMs. Sulfoxide reduction also occurred in HLMs without NADPH or in deactivated HLMs. Ilaprazole sulfide and its multiple oxidative metabolites were major drug-related components in human urine and feces, where there were no ilaprazole sulfone and its metabolites. A small amount of the parent drug was found in feces. Thus, we propose that nonenzymatic sulfoxide reduction rather than CYP3A4-medidated sulfoxide oxidation is the major metabolic clearance pathway of ilaprazole in humans. Consequently, it is predicted that ilaprazole has no significant drug-drug interaction via CYP3A4 inhibition or induction by a coadministered drug.

Proton Pump Inhibitors and Dementia: Physiopathological Mechanisms and Clinical Consequences.

Alzheimer's disease (AD) is the most common type of dementia, mainly encompassing cognitive decline in subjects aged ≥65 years. Further, AD is characterized by selective synaptic and neuronal degeneration, vascular dysfunction, and two histopathological features: extracellular amyloid plaques composed of amyloid beta peptide (Aß) and neurofibrillary tangles formed by hyperphosphorylated tau protein. Dementia and AD are chronic neurodegenerative conditions with a complex physiopathology involving both genetic and environmental factors. Recent clinical studies have shown that proton pump inhibitors (PPIs) are associated with risk of dementia, including AD. However, a recent case-control study reported decreased risk of dementia. PPIs are a widely indicated class of drugs for gastric acid-related disorders, although most older adult users are not treated for the correct indication. Although neurological side effects secondary to PPIs are rare, several preclinical reports indicate that PPIs might increase Aß levels, interact with tau protein, and affect the neuronal microenvironment through several mechanisms. Considering the controversy between PPI use and dementia risk, as well as both cognitive and neuroprotective effects, the aim of this review is to examine the relationship between PPI use and brain effects from a neurobiological and clinical perspective.

Drug-drug interactions in patients receiving tyrosine kinase inhibitors.

Rationale Tyrosine kinase inhibitors are increasingly used in the treatment of cancer. Drug interactions involving tyrosine kinase inhibitors are commonly encountered in clinical practice. The objective of this study was to describe the frequency of tyrosine kinase inhibitor-associated drug interactions among a cohort of oncology patients. Methods Adult patients were included who presented to either of two outpatient oncology practices and were prescribed a tyrosine kinase inhibitor during 2 January 2013 to 1 January 2015. Demographic and medication data were abstracted from electronic medical records. Lexicomp®, Micromedex Solutions®, and medication labeling were utilized to identify potential interactions between tyrosine kinase inhibitors and concomitant medications. Interactions were then assessed by the investigators for clinical significance. The primary outcome was the frequency of significant drug interactions involving tyrosine kinase inhibitors and concomitant medications. Secondary outcomes included describing the nature and clinical impact of interactions, and describing interactions by medication class. Results A total of 356 patients were identified for analysis, in whom 244 potential interactions were identified, and 109 (44.7%) of which were considered severe. Decreased tyrosine kinase inhibitor absorption due to acid suppressive therapy and CYP3A4 interactions were the most frequent mechanisms of potential subtherapeutic and supratherapeutic concentrations, respectively. Potential clinical consequences included QTc prolongation ( n = 53, 48.6%), decreased tyrosine kinase inhibitor concentration ( n = 53, 48.6%), and increased tyrosine kinase inhibitor concentration ( n = 3, 2.8%). Conclusions Safer alternative therapy and/or more frequent clinical monitoring should be considered if an interaction poses a significant risk of increased tyrosine kinase inhibitor toxicity or decreased tyrosine kinase inhibitor efficacy. Oncology pharmacists can play a role in screening for tyrosine kinase inhibitor-associated interactions, recommending alternative therapies or dosing strategies, and monitoring tyrosine kinase inhibitor efficacy and toxicity.