Effect of white jade snail secretion on antioxidant capacity and intestinal microbial diversity in mouse model of acute gastric ulcer.

BACKGROUND: In the present work, acute gastric ulcer models were constructed by administering hydrochloric acid/ethanol. The mice ingested white jade snail secretion (WJSS) through gastric infusion. Ulcer areas in gastric tissue were recorded, and malondialdehyde (MDA) and superoxide dismutase (SOD) were also measured. Notably, high-throughput 16S rDNA analysis of intestinal flora and determination of amino acid composition in feces were performed to understand the effect of WJSS on model mice. RESULTS: Compared with the control group, the ulcer area in the WJSS low-, medium- and high-concentration groups declined by 28.02%, 39.57% and 77.85%, respectively. MDA content decreased by 24.71%, 49.58% and 64.25%, and SOD relative enzyme activity fell by 28.19%, 43.37% and 9.60%, respectively. The amounts of amino acids in the low-, medium- and high-concentration groups were slightly lower, and probiotic bacteria such as Bacteroidetes and Lactobacillales increased in different-concentration WJSS groups. Adding WJSS contributes to the establishment of beneficial intestinal flora and the absorption of amino acids. CONCLUSION: Our results showed that WJSS has a beneficial effect on inhibiting hydrochloric acid-ethanolic gastric ulcers, suggesting that WJSS has excellent potential as a novel anti-ulcer agent. Combined with ulcer area, MDA content, SOD content, gut probiotics and other indicators, a high concentration of WJSS had the best protective effect on acute gastric ulcer. © 2023 Society of Chemical Industry.

Synthesis and biological evaluation of new nicotinate derivatives as potential anti-inflammatory agents targeting COX-2 enzyme.

Two novel series derived from nicotinic acid were synthesized and evaluated for their inhibitory activity against cyclooxygenases COX-1 and COX-2, and their selectivity indices were determined. Celecoxib, diclofenac and indomethacin were used as reference drugs. All compounds showed highly potent COX-2 inhibitory activity and higher selectivity towards COX-2 inhibition compared to indomethacin. In addition, these compounds except 3a showed clear preferential COX-2 over COX-1 inhibition compared to diclofenac. Compounds 3b, 3e, 4c and 4f showed COX-2 inhibitory activity equipotent to celecoxib. Compounds 4c and 4f demonstrated selectivity indices 1.8-1.9 fold higher than celecoxib. These two most potent and COX-2 selective compounds were further tested in vivo for anti-inflammatory activity by means of carrageenan induced rat paw edema method. Ulcerogenic activity with histopathological studies were performed. The results showed no ulceration, which implies their safe gastric profile. Compound 4f exhibited the most potent in vivo anti-inflammatory activity comparable to all reference drugs. Further, compounds 4c and 4f were investigated for their influence on certain inflammatory cytokines TNF-α and IL-1ß in addition to PEG2. The findings revealed that these candidates could be identified as promising potent anti-inflammatory agents. Molecular docking of 4c and 4f in the COX-2 active site was performed to rationalize their COX-2 inhibitory potency. The results were found to be in line with the biological findings as they exerted more favorable interactions compared to that of celecoxib, explaining their remarkable COX-2 inhibitory activity.

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.

Pharmacokinetic and pharmacodynamic evidence for developing an oral formulation of octreotide against gastric mucosal injury.

Among the somatostatin analogues, octreotide (OCT) is the most commonly used in clinic via intravenous or subcutaneous injection to treat various diseases caused by increased secretion of growth hormone, gastrin or insulin. In order to assesse the feasibility of developing oral formulations of OCT, we conducted systematical pharmacokinetic and pharmacodynamic analyses of OCT in several animal models. The pharmacokinetic studies in rats showed that intragastric administration of OCT had extremely low bioavailability (<0.5%), but it could specifically distribute to the gastric mucosa due to the high expression of somatostatin receptor 2 (SSTR2) in the rat stomach. The pharmacodynamic studies revealed that intragastric administration of OCT dose-dependently protected against gastric mucosal injury (GMI) in mice with WIRS-induced mouse gastric ulcers, which were comparable to those achieved by intravenous injection of OCT, and this effect was markedly attenuated by co-administration of CYN-154806, an antagonist of SSTR2. In pyloric ligation-induced ulcer mice, we further demonstrated that OCT significantly reduced the secretion of gastric acid via down-regulating the level of gastrin, which was responsible for the protective effect of OCT against GMI. Overall, we have provided pharmacokinetic and pharmacodynamic evidence for the feasibility of developing an oral formulation of OCT. Most importantly, the influence of SSTR2 on the pharmacokinetics and pharmacodynamics of OCT suggested that an oral formulation of OCT might be applicable for other clinical indications, including neuroendocrine neoplasms and pituitary adenoma due to the overexpression of SSTR2 on these tumor cells.

Protective effect of salusin-α and salusin-ß against ethanol-induced gastric ulcer in rats.

BACKGROUND: Alcohol consumption has been found to be associated with gastric ulcers, including gastric mucosal lesions. Salusin-α and salusin-ß are bioactive peptides having 28 and 20 amino acids, respectively. Salusin-α and salusin-ß immunoreactivity has been detected in the stomach and in the intestines. It has been reported that the salusins regulate the cytokine levels and decrease the infarct area in the heart tissue after ischemia. In this study, we investigated the effects of the salusins in the gastric injury formed with ethanol. METHODS: Thirty-two sprague Dawley male rats were randomly divided into four groups, including eight rats in each group as follows: Group 1: control; Group 2: ethanol 5 mL/kg; Group 3: ethanol 5 mL/kg+5 nmol/kg salusin-α; Group 4: ethanol 5 mL/kg+5 nmol/kg salusin-ß. RESULTS: The salusin-α level increased at a significant level in the ulcer group formed with ethanol (p<0.001); the change in the salusin-ß level is not significant. As for malondialdehyde (p<0.05) and myeloperoxidase (p<0.001), when compared with the control group, tumor necrosis factor-α (p<0.05) levels increased in the group to which ethanol was applied and decreased significantly with the application of salusins. Levels of GSH and IL-1ß did not change at a significant level. In addition, histopathologic analysis demonstrated that, in salusin-administered groups, mucosal injury and caspase-3 expressions were reduced. CONCLUSIONS: The suppression of salusin-α and salusin-ß on caspase-3 expression by means of their effects on oxidative injury and TNF-α levels shows that these two hormones could serve as anti-ulcerative agents.

Effect of proinflammatory cytokine IL-6 on efflux transport of rebamipide in Caco-2 cells.

1. Effect of IL-6, a pro-inflammatory cytokine, on efflux transport of rebamipide, an antiulcer drug, was investigated in Caco-2 cells. 2. Rebamipide had a greater basal-to-apical than apical-to-basal transport rate. Efflux transport of rebamipide was inhibited by cyclosporine A, a P-gp inhibitor, and probenecid, which is a general MRP inhibitor, but not by Ko143, a BCRP inhibitor. 3. By the addition of IL-6, mannitol transport was slightly increased in a concentration-dependent manner in both directions of absorption and efflux. The addition of IL-6 did not change efflux transport of rebamipide even though efflux transport of digoxin, a typical substrate of P-gp, was significantly decreased by the addition of IL-6, indicating decrease of the function of P-gp. 4. Therefore, it was suggested that increase of MRP(s)-mediated transport compensates for the decrease of P-gp mediated transport of rebamipide. These findings suggested that rebamipide absorption is unlikely to be changed in IBD patients.

Safety and anti-ulcerogenic activity of a novel polyphenol-rich extract of clove buds (Syzygium aromaticum L).

Despite the various reports on the pharmacology of Clove bud [Syzygium aromaticum]-derived essential oil and its major component eugenol, systematic information on the bioactivity of clove polyphenols is very limited. Clove buds being one of the richest sources of dietary polyphenols with many traditional medicinal uses, the present contribution attempted to derive their standardized polyphenol-rich extracts as a water soluble free flowing powder (Clovinol) suitable for functional food applications, without the issues of its characteristic pungency and aroma. The extract was characterized by electrospray ionization-time of flight mass spectrometry (ESI-TOF-MS), and investigated for in vivo antioxidant, anti-inflammatory and anti-ulcerogenic activities. Clovinol showed significant antioxidant and anti-inflammatory effects as measured by cellular antioxidant levels, and the ability to inhibit carrageenan-induced paw swelling in mice. Further investigations revealed its significant anti-ulcerogenic activity (>97% inhibition of ethanol-induced stomach ulcers in Wistar rats when orally administered at 100 mg per kg b.w.) and up regulation of in vivo antioxidants such as superoxide dismutase (SOD), glutathione (GSH), and catalase (CAT). Clovinol also reduced the extent of lipid peroxidation among ulcer induced rats, indicating its usefulness in ameliorating oxidative stress and improving gastrointestinal health, especially upon chronic alcohol consumption. The extract was also shown to be safe and suitable for further investigations and development upon acute toxicity studies at 5 g per kg body weight and 28 days of repeated dose toxicity studies at 2.5 g per kg b.w.

Enhanced oral absorption of hydrophobic and hydrophilic drugs using quaternary ammonium palmitoyl glycol chitosan nanoparticles.

As 95% of all prescriptions are for orally administered drugs, the issue of oral absorption is central to the development of pharmaceuticals. Oral absorption is limited by a high molecular weight (>500 Da), a high log P value (>2.0) and low gastrointestinal permeability. We have designed a triple action nanomedicine from a chitosan amphiphile: quaternary ammonium palmitoyl glycol chitosan (GCPQ), which significantly enhances the oral absorption of hydrophobic drugs (e.g., griseofulvin and cyclosporin A) and, to a lesser extent, the absorption of hydrophilic drugs (e.g., ranitidine). The griseofulvin and cyclosporin A C(max) was increased 6- and 5-fold respectively with this new nanomedicine. Hydrophobic drug absorption is facilitated by the nanomedicine: (a) increasing the dissolution rate of hydrophobic molecules, (b) adhering to and penetrating the mucus layer and thus enabling intimate contact between the drug and the gastrointestinal epithelium absorptive cells, and (c) enhancing the transcellular transport of hydrophobic compounds. Although the C(max) of ranitidine was enhanced by 80% with the nanomedicine, there was no appreciable opening of tight junctions by the polymer particles.

Clinical update on nursing home medicine: 2011.

This represents the fifth article in the series on yearly updates of hot topics in long term care.

Coenzyme Q10: a novel gastroprotective effect via modulation of vascular permeability, prostaglandin E2, nitric oxide and redox status in indomethacin-induced gastric ulcer model.

Coenzyme Q10 is an essential cofactor in the mitochondrial electron transport pathway, and is endowed for its potent antioxidant capacity; characters that endorse its implication in several clinical practices and as a food supplement. Nevertheless, its potential gastro-protective effect, in acute models, has never been assessed, which is the objective of this study. Since indomethacin mediated gastropathy is multifaceted, including mitochondrial dysfunction and generation of reactive oxygen species, thus, the indomethacin-induced gastric injury serves as a convenient animal model for this work. Rats treated with indomethacin revealed mucosal hemorrhagic lesions, increased microvascular permeability and inhibited prostaglandin E2 and mucus content. Redox imbalance was reflected by decreased mucosal glutathione (GSH), nitric oxide and glutathione peroxidase contents/activity, along with elevated lipid peroxides. Pretreatment with CoQ10 caused discernible decrease in indomethacin-induced gastric lesions, vascular permeability and lipid peroxide content. In addition, prostaglandin E2 and GSH levels were restored, while those of nitric oxide and glutathione peroxidase were elevated significantly above normal; however, mucus formation was not altered significantly. The positive effects were comparable to those of sucralfate, the standard drug used herein, except for the mucus and prostaglandin E2 levels that were increased above normal by sucralfate. CoQ10-mediated gastroprotective effect involves preservation of microvascular permeability, elevation of prostaglandin E2, improvement of redox status, as well as boosting of nitric oxide. Nevertheless, maintaining gastric mucus content is ruled out.

Helicobacter pylori: a ROS-inducing bacterial species in the stomach.

BACKGROUND: Reactive oxygen species (ROS) and reactive nitrogen species (RNS) have been reported to impact gastric inflammation and carcinogenesis. However, the precise mechanism by which Helicobacter pylori induces gastric carcinogenesis is presently unclear. AIM: This review focuses on H. pylori-induced ROS/RNS production in the host stomach, and its relationship with gastric carcinogenesis. RESULTS: Activated neutrophils are the main source of ROS/RNS production in the H. pylori-infected stomach, but H. pylori itself also produces ROS. In addition, extensive recent studies have revealed that H. pylori-induced ROS production in gastric epithelial cells might affect gastric epithelial cell signal transduction, resulting in gastric carcinogenesis. Excessive ROS/RNS production in the stomach can damage DNA in gastric epithelial cells, implying its involvement in gastric carcinogenesis. CONCLUSION: Understanding the molecular mechanism behind H. pylori-induced ROS, and its involvement in gastric carcinogenesis, is important for developing new strategies for gastric cancer chemoprevention.

Controlled delivery of ranitidine in the stomach using magnetic field / Administración controlada de ranitidina en el estómago usando campos magnéticos

An attempt has been made to localize ranitidine loaded microspheres in the stomach by magnetic means. Since ranitidine undergoes metabolism by microbial enzymes in the intestine, it is ideal to localize the controlled drug delivery system within the stomach to get uniform release and absorption of the drug for the desired period. Gelatin magnetic microspheres loaded with 9.1, 17.9, 26.3 and 33.3% w/w of ranitidine hydrochloride were prepared by emulsification-cross linking technique. The formulated microspheres were characterized by magnetite content, particle size and in vitro drug release. The efficiency of microspheres to be localized in the stomach is tested in vivo in rats. The prepared microspheres were spherical and had a size distribution from 10 to 105 µm. The in vitro study revealed the capability of microspheres to release the drug over a period of 8 to 12 hours, depending on drug loading. The release was found to be diffusion controlled and followed fickian diffusion principle. The in vivo study showed the efficiency of microspheres to be retained in the stomach over a period of 8 hours.

Se ha hecho el intento por localizar las microesferas cargadas de ranitidina en el estómago mediante medios magnéticos. Como que la ranitidina experimenta metabolismo mediante enzimas microbianas en el intestino, resulta ideal localizar el sistema de administración del medicamento controlado dentro del estómago para alcanzar la liberación y absorción uniformes del medicamento por el período deseado. Microesferas de gelatina magnética cargadas con 9.1, 17.9, 26.3 y 33.3% p/p de hidrocloruro de ranitidina, fueron preparadas mediante una técnica de emulsificación-entrecruzamiento. Las microesferas formuladas se caracterizaron por su contenido de magnetita, el tamaño de las partículas y la liberación del medicamento in vitro. La eficiencia de las microesferas a ser localizadas en el estómago se prueba in vivo en ratas. Las microesferas preparadas eran esféricas y tenían una distribución de tamaño de 10 a 105 µm. El estudio in vitro reveló la capacidad de las microesferas para liberar la droga en un período de 8 a 12 horas, en dependencia de la carga de la droga. Se halló que la liberación estaba sujeta difusión controlada y seguía la ley de Fick para la difusión. El estudio in vivo mostró la eficiencia de las microesferas para ser retenidas en el estómago por un período de 8 horas.

CYP2C19 pharmacogenetics in advanced cancer: compromised function independent of genotype.

CYP2C19 is a drug-metabolising enzyme involved in the metabolism of a number of chemotherapeutic agents including cyclophosphamide. Variants of the CYP2C19 gene result in a loss of function polymorphism, which affects approximately 3% of the Caucasian population. These individuals are poor metabolisers (PM) of a wide range of medications including omeprazole (OMP). In healthy subjects PM can be identified through homozygous variant genotype. However, a discordance between CYP2C19 genotype and phenotype has been reported previously in a small study of cancer patients. To investigate whether CYP2C19 activity was decreased in patients with advanced cancer, CYP2C19 genotype was determined in 33 advanced cancer patients using PCR-RFLP analysis for the two important allelic variants (*2,681G>A and *3,636G>A) and the activity of the enzyme was evaluated using the CYP2C19 probe drug OMP. The activity of the drug-metabolising enzyme CYP2C19 was severely compromised in advanced cancer patients, resulting in a PM status in 37% of the patients who had normal genotype. This is significantly (P<0.0005) higher than that would be predicted from the genotypic status of these patients. There was no evidence of a correlation between compromised CYP2C19 activity and any of the proinflammatory cytokines or acute phase response proteins studied. However, there was preliminary evidence of an association between PM status and low body mass (P=0.03). There is increasing interest in using pharmacogenetics to 'individualise medicine', however, the results of this study indicate that in a cancer population genotyping for CYP2C19 would significantly underestimate the number of phenotypic PM of drugs, such as cyclophosphamide, which may be metabolised by this enzyme.

Diet-derived nutrients modulate the effects of amylin on c-Fos expression in the area postrema and on food intake.

The pancreatic hormone amylin decreases food intake via activation of area postrema (AP) neurons. We investigated whether amylin's potency to reduce food intake and to induce c-Fos expression in the AP/nucleus of the solitary tract region is affected by the feeding conditions and specifically by the macronutrient composition of the diet. Whereas a low dose of amylin (5 microg/kg s.c.) induced very little c-Fos expression in ad libitum chow fed rats, it caused a strong c-Fos expression in 24-hour food-deprived rats and in rats that received a nutrient-deficient non-caloric mash (NCM; vanilla-flavoured cellulose) 24 h before injection. To reveal the contribution of single nutrients to the low c-Fos expression after chow feeding, amylin-induced c-Fos was analyzed after feeding NCM that was selectively supplemented with glucose, fat (lard), or protein (casein), matching the intake of these nutrients of chow-fed rats. While the rats fed NCM supplemented with glucose or fat displayed an equally strong amylin-induced activation as fasted rats or rats fed plain NCM, a significantly lower c-Fos expression was observed in rats fed a protein-supplemented NCM or a NCM containing all three nutrients. In line with this lower activation, the same dose of amylin failed to reduce food intake in NCM/protein-fed rats, while amylin caused a reduction in feeding when animals received NCM, NCM/glucose, or NCM/fat. Interestingly, amylin effectively reduced food intake in ad libitum chow fed rats despite the low level of amylin-induced c-Fos expression in the AP under these conditions. We conclude that the anorectic potential of amylin may be attenuated by diet-derived proteins, whereas this effect appears to be overridden when the amount of carbohydrates/fat is high relative to the protein content, such as, e.g., in standard chow.

The gastric H,K ATPase as a drug target: past, present, and future.

The recent progress in therapy if acid disease has relied heavily on the performance of drugs targeted against the H,K ATPase of the stomach and the H2 receptor antagonists. It has become apparent in the last decade that the proton pump is the target that has the likelihood of being the most sustainable area of therapeutic application in the regulation of acid suppression. The process of activation of acid secretion requires a change in location of the ATPase from cytoplasmic tubules into the microvilli of the secretory canaliculus of the parietal cell. Stimulation of the resting parietal cell, with involvement of F-actin and ezrin does not use significant numbers of SNARE proteins, because their message is depleted in the pure parietal cell transcriptome. The cell morphology and gene expression suggest a tubule fusion-eversion event. As the active H,K ATPase requires efflux of KCl for activity we have, using the transcriptome derived from 99% pure parietal cells and immunocytochemistry, provided evidence that the KCl pathway is mediated by a KCQ1/KCNE2 complex for supplying K and CLIC6 for supplying the accompanying Cl. The pump has been modeled on the basis of the structures of different conformations of the sr Ca ATPase related to the catalytic cycle. These models use the effects of site directed mutations and identification of the binding domain of the K competitive acid pump antagonists or the defined site of binding for the covalent class of proton pump inhibitors. The pump undergoes conformational changes associated with phosphorylation to allow the ion binding site to change exposure from cytoplasmic to luminal exposure. We have been able to postulate that the very low gastric pH is achieved by lysine 791 motion extruding the hydronium ion bound to carboxylates in the middle of the membrane domain. These models also allow description of the K entry to form the K liganded form of the enzyme and the reformation of the ion site inward conformation thus relating the catalytic cycle of the pump to conformational models. The mechanism of action of the proton pump inhibitor class of drug is discussed along with the cysteines covalently bound with these inhibitors. The review concludes with a discussion of the mechanism of action and binding regions of a possible new class of drug for acid control, the K competitive acid pump antagonists.

Hyperthermia ameliorates 2,4,6-trinitrobenzene sulphonic acid-induced colitis in rats: the role of heat shock proteins.

PURPOSE: Hyperthermia is known to protect against cellular injury through the expression of heat shock proteins. In this study, the therapeutic effects of hyperthermia on experimental colitis in the rat were evaluated. MATERIALS AND METHODS: Male Wistar rats were given a single intracolonic injection of 2,4,6-trinitrobenzene sulphonic acid (TNBS). Hyperthermia was induced in anesthetized rats by placing them in a temperature-controlled water bath. We started the hyperthermic treatment on the day after the enema. The severity of colitis was evaluated pathologically, and the activities of tissue myeloperoxidase were measured 6 days after the induction of colitis. Furthermore, cytokines, and hyperthermia-induced heat shock proteins in colonic mucosa were detected by enzyme-linked immunosorbent assay and Western blotting. We also investigated the effects of geranylgeranylacetone and zinc protoporphyrin IX on the therapeutic effect of hyperthermia. RESULTS: Hyperthermia significantly improved the macroscopic scores of colitis. The TNBS-induced increases in the activities of myeloperoxidase in the colonic tissue were blunted significantly in hyperthermia-treated animals. Furthermore, hyperthermia attenuated increases in cytokine-induced neutrophil chemoattractants-1 and tumor necrosis factor-alpha in the colon. Furthermore, hyperthermia induced the production of heat shock proteins in rat colonic mucosa, and the combination of geranylgeranylacetone with hyperthermia further induced the heat shock protein HSP70, which resulted in further improvement of TNBS-induced colitis. On the other hand, the combination of zinc protoporphyrin IX with hyperthermia attenuated the therapeutic effect of hyperthermia. CONCLUSIONS: Hyperthermia ameliorates TNBS-induced colitis in rats through the expression of HSP70 and HO-1. It is postulated that hyperthermia may be useful for the treatment of inflammatory bowel diseases.

Pharmacokinetic drug interaction profiles of proton pump inhibitors.

Proton pump inhibitors are used extensively for the treatment of gastric acid-related disorders because they produce a greater degree and longer duration of gastric acid suppression and, thus, better healing rates, than histamine H(2) receptor antagonists. The need for long-term treatment of these disorders raises the potential for clinically significant drug interactions in patients receiving proton pump inhibitors and other medications. Therefore, it is important to understand the mechanisms for drug interactions in this setting. Proton pump inhibitors can modify the intragastric release of other drugs from their dosage forms by elevating pH (e.g. reducing the antifungal activity of ketoconazole). Proton pump inhibitors also influence drug absorption and metabolism by interacting with adenosine triphosphate-dependent P-glycoprotein (e.g. inhibiting digoxin efflux) or with the cytochrome P450 (CYP) enzyme system (e.g. decreasing simvastatin metabolism), thereby affecting both intestinal first-pass metabolism and hepatic clearance. Although interactions based on the change of gastric pH are a group-specific effect and thus may occur with all proton pump inhibitors, individual proton pump inhibitors differ in their propensities to interact with other drugs and the extent to which their interaction profiles have been defined. The interaction profiles of omeprazole and pantoprazole have been studied most extensively. A number of studies have shown that omeprazole carries a considerable potential for drug interactions, since it has a high affinity for CYP2C19 and a somewhat lower affinity for CYP3A4. In contrast, pantoprazole appears to have lower potential for interactions with other medications. Although the interaction profiles of esomeprazole, lansoprazole and rabeprazole have been less extensively investigated, evidence suggests that lansoprazole and rabeprazole seem to have a weaker potential for interactions than omeprazole. Although only a few drug interactions involving proton pump inhibitors have been shown to be of clinical significance, the potential for drug interactions should be taken into account when choosing a therapy for gastric acid-related disorders, especially for elderly patients in whom polypharmacy is common, or in those receiving a concomitant medication with a narrow therapeutic index.

CYP2C19 genotype and the PPIs--focus on rabeprazole.

Amongst all the proton pump inhibitors (PPI), the hepatic metabolism of rabeprazole is least dependent on the CYP4502C19 system. Rabeprazole is therefore the PPI least affected by CYP4502C19 genetic polymorphism. This unique feature of rabeprazole complements rabeprazole's fast onset of action, and may lead to profound and consistent inhibition of gastric acid secretion in the treatment of acid-related disorders.

Inducers and co-inducers of molecular chaperones.

Molecular chaperones, which are mostly heat- or stress-induced proteins (HSPs), not only regulate various cellular functions such as protein folding, refolding of partially denatured proteins, protein transport across membranes, cytoskeletal organization, degradation of disabled proteins, and apoptosis, but also act as cytoprotective factors against deleterious environmental stresses. Recent studies indicated that moderate overexpression of molecular chaperones could confer cells and tissues stress tolerance and provide beneficial effects on various pathological states associated with protein misfolding and protein aggregation. Mild heat shock, transfection of HSP genes, and some chemical compounds are the major means of overexpression of molecular chaperones. In this review, we summarize recent studies of chemical compounds that could induce or enhance the expression of molecular chaperones or HSPs.