Pharmacokinetic drug interaction profiles of proton pump inhibitors

Data-driven prediction of adverse drug reactions induced by drug-drug interactions

Background

The expanded use of multiple drugs has increased the occurrence of adverse drug reactions (ADRs) induced by drug-drug interactions (DDIs). However, such reactions are typically not observed in clinical drug-development studies because most of them focus on single-drug therapies. ADR reporting systems collect information on adverse health effects caused by both single drugs and DDIs. A major challenge is to unambiguously identify the effects caused by DDIs and to attribute them to specific drug interactions. A computational method that provides prospective predictions of potential DDI-induced ADRs will help to identify and mitigate these adverse health effects.

Method

We hypothesize that drug-protein interactions can be used as independent variables in predicting ADRs. We constructed drug pair-protein interaction profiles for ~800 drugs using drug-protein interaction information in the public domain. We then constructed statistical models to score drug pairs for their potential to induce ADRs based on drug pair-protein interaction profiles.

Results

We used extensive clinical database information to construct categorical prediction models for drug pairs that are likely to induce ADRs via synergistic DDIs and showed that model performance deteriorated only slightly, with a moderate amount of false positives and false negatives in the training samples, as evaluated by our cross-validation analysis. The cross validation calculations showed an average prediction accuracy of 89% across 1,096 ADR models that captured the deleterious effects of synergistic DDIs. Because the models rely on drug-protein interactions, we made predictions for pairwise combinations of 764 drugs that are currently on the market and for which drug-protein interaction information is available. These predictions are publicly accessible at http://avoid-db.bhsai.org. We used the predictive models to analyze broader aspects of DDI-induced ADRs, showing that ~10% of all combinations have the potential to induce ADRs via DDIs. This allowed us to identify potential DDI-induced ADRs not yet clinically reported. The ability of the models to quantify adverse effects between drug classes also suggests that we may be able to select drug combinations that minimize the risk of ADRs.

Conclusion

Almost all information on DDI-induced ADRs is generated after drug approval. This situation poses significant health risks for vulnerable patient populations with comorbidities. To help mitigate the risks, we developed a robust probabilistic approach to prospectively predict DDI-induced ADRs. Based on this approach, we developed prediction models for 1,096 ADRs and used them to predict the propensity of all pairwise combinations of nearly 800 drugs to be associated with these ADRs via DDIs. We made the predictions publicly available via internet access.

Electronic supplementary material

The online version of this article (doi:10.1186/s40360-017-0153-6) contains supplementary material, which is available to authorized users.

Successful treatment of a hemodialyzed patient with pure red cell aplasia associated with epoetin beta pegol therapy with cyclosporine

A 42-year-old man with end-stage renal failure had been receiving hemodialysis therapy since April 2009. Initially, darbepoetin alfa was administered to treat his renal anemia. After treatment was switched to epoetin beta pegol, the patient's hemoglobin levels rapidly decreased. He was diagnosed with pure red cell aplasia (PRCA) based on the results of a bone marrow examination. Epoetin beta pegol was strongly suspected to be the cause of the PRCA, and although he tested negative for anti-epoetin beta pegol antibodies, epoetin beta pegol was discontinued and cyclosporine therapy was initiated. Thereafter, his hemoglobin levels increased, and his anemia dramatically improved after 3 months.

The Oral β-Lactamase SYN-004 (Ribaxamase) Degrades Ceftriaxone Excreted into the Intestine in Phase 2a Clinical Studies

SYN-004 (ribaxamase) is a β-lactamase designed to be orally administered concurrently with intravenous β-lactam antibiotics, including most penicillins and cephalosporins. Ribaxamase's anticipated mechanism of action is to degrade excess β-lactam antibiotic that is excreted into the small intestine. This enzymatic inactivation of excreted antibiotic is expected to protect the gut microbiome from disruption and thus prevent undesirable side effects, including secondary infections such as Clostridium difficile infections, as well as other antibiotic-associated diarrheas. In phase 1 clinical studies, ribaxamase was well tolerated compared to a placebo group and displayed negligible systemic absorption. The two phase 2a clinical studies described here were performed to confirm the mechanism of action of ribaxamase, degradation of β-lactam antibiotics in the human intestine, and were therefore conducted in subjects with functioning ileostomies to allow serial sampling of their intestinal chyme. Ribaxamase fully degraded ceftriaxone to below the level of quantitation in the intestines of all subjects in both studies. Coadministration of oral ribaxamase with intravenous ceftriaxone was also well tolerated, and the plasma pharmacokinetics of ceftriaxone were unchanged by ribaxamase administration. Since ribaxamase is formulated as a pH-dependent, delayed-release formulation, the activity of ribaxamase in the presence of the proton pump inhibitor esomeprazole was examined in the second study; coadministration of these drugs did not adversely affect ribaxamase's ability to degrade ceftriaxone excreted into the intestine. These studies have confirmed the in vivo mechanism of action of ribaxamase, degradation of β-lactam antibiotics in the human intestine (registered at ClinicalTrials.gov under NCT02419001 and NCT02473640).

Micromotors Spontaneously Neutralize Gastric Acid for pH-Responsive Payload Release

The highly acidic gastric environment creates a physiological barrier for using therapeutic drugs in the stomach. While proton pump inhibitors have been widely used for blocking acid-producing enzymes, this approach can cause various adverse effects. Reported herein is a new microdevice, consisting of magnesium-based micromotors which can autonomously and temporally neutralize gastric acid through efficient chemical propulsion in the gastric fluid by rapidly depleting the localized protons. Coating these micromotors with a cargo-containing pH-responsive polymer layer leads to autonomous release of the encapsulated payload upon gastric-acid neutralization by the motors. Testing in a mouse model demonstrate that these motors can safely and rapidly neutralize gastric acid and simultaneously release payload without causing noticeable acute toxicity or affecting the stomach function, and the normal stomach pH is restored within 24 h post motor administration.

Influence of different proton pump inhibitors on the pharmacokinetics of voriconazole

This study aimed to determine the influence of proton pump inhibitors (PPIs) on the pharmacokinetics of voriconazole and to characterise potential drug-drug interactions (DDIs) between voriconazole and various PPIs (omeprazole, esomeprazole, lansoprazole and rabeprazole). Using adjusted physicochemical data and the pharmacokinetic (PK) parameters of voriconazole and PPIs, physiologically based pharmacokinetic (PBPK) models were built and were verified in healthy subjects using GastroPlus^TM to predict the plasma concentration-time profiles of voriconazole and PPIs. These models were then used to assess potential DDIs for voriconazole when administered with PPIs. The results indicated the PBPK model-simulated plasma concentration-time profiles of both voriconazole and PPIs were consistent with the observed profiles. In addition, the DDI simulations suggested that the PK values of voriconazole increased to various degrees when combined with several PPIs. The area under the plasma concentration-time curve for the time of the simulation (AUC_0-t) of voriconazole was increased by 39%, 18%, 12% and 1% when co-administered with omeprazole, esomeprazole, lansoprazole and rabeprazole, respectively. Omeprazole was the most potent CYP2C19 inhibitor tested, whereas rabeprazole had no influence on voriconazole (omeprazole > esomeprazole > lansoprazole > rabeprazole). However, in consideration of the therapeutic concentration range, dosage adjustment of voriconazole is unnecessary regardless of which PPI was co-administered.

Gastroduodenal Ulceration in Small Animals: Part 2. Proton Pump Inhibitors and Histamine-2 Receptor Antagonists

In the first part of this review, we discussed the pathophysiology and epidemiology of gastric acid secretion and the epidemiology of gastroduodenal ulceration in dogs and cats. In this section, we discuss the pharmacology and evidence-based clinical use of histamine-2 receptor antagonists and proton pump inhibitors.

Effective and safe proton pump inhibitor therapy in acid-related diseases - A position paper addressing benefits and potential harms of acid suppression

BACKGROUND

The introduction of proton pump inhibitors (PPIs) into clinical practice has revolutionized the management of acid-related diseases. Studies in primary care and emergency settings suggest that PPIs are frequently prescribed for inappropriate indications or for indications where their use offers little benefit. Inappropriate PPI use is a matter of great concern, especially in the elderly, who are often affected by multiple comorbidities and are taking multiple medications, and are thus at an increased risk of long-term PPI-related adverse outcomes as well as drug-to-drug interactions. Herein, we aim to review the current literature on PPI use and develop a position paper addressing the benefits and potential harms of acid suppression with the purpose of providing evidence-based guidelines on the appropriate use of these medications.

METHODS

The topics, identified by a Scientific Committee, were assigned to experts selected by three Italian Scientific Societies, who independently performed a systematic search of the relevant literature using Medline/PubMed, Embase, and the Cochrane databases. Search outputs were distilled, paying more attention to systematic reviews and meta-analyses (where available) representing the best evidence. The draft prepared on each topic was circulated amongst all the members of the Scientific Committee. Each expert then provided her/his input to the writing, suggesting changes and the inclusion of new material and/or additional relevant references. The global recommendations were then thoroughly discussed in a specific meeting, refined with regard to both content and wording, and approved to obtain a summary of current evidence.

RESULTS

Twenty-five years after their introduction into clinical practice, PPIs remain the mainstay of the treatment of acid-related diseases, where their use in gastroesophageal reflux disease, eosinophilic esophagitis, Helicobacter pylori infection, peptic ulcer disease and bleeding as well as, and Zollinger-Ellison syndrome is appropriate. Prevention of gastroduodenal mucosal lesions (and symptoms) in patients taking non-steroidal anti-inflammatory drugs (NSAIDs) or antiplatelet therapies and carrying gastrointestinal risk factors also represents an appropriate indication. On the contrary, steroid use does not need any gastroprotection, unless combined with NSAID therapy. In dyspeptic patients with persisting symptoms, despite successful H. pylori eradication, short-term PPI treatment could be attempted. Finally, addition of PPIs to pancreatic enzyme replacement therapy in patients with refractory steatorrhea may be worthwhile.

CONCLUSIONS

Overall, PPIs are irreplaceable drugs in the management of acid-related diseases. However, PPI treatment, as any kind of drug therapy, is not without risk of adverse effects. The overall benefits of therapy and improvement in quality of life significantly outweigh potential harms in most patients, but those without clear clinical indication are only exposed to the risks of PPI prescription. Adhering with evidence-based guidelines represents the only rational approach to effective and safe PPI therapy. Please see related Commentary: doi: 10.1186/s12916-016-0724-1 .

Different effects of lansoprazole and rabeprazole on the plasma voriconazole trough levels in allogeneic hematopoietic cell transplant recipients

Voriconazole (VRC) is widely used as prophylaxis and in the treatment of invasive fungal disease (IFD) after allogeneic hematopoietic cell transplantation (HCT). We retrospectively examined the results of VRC therapeutic drug monitoring (TDM) in allogeneic HCT recipients. A total of 474 samples were obtained from 59 adult patients who received VRC during the first 100 days following HCT between 2009 and 2014 in our institute. Seventeen patients received VRC for prophylaxis of IFD, and 42 received VRC for the empirical or preemptive therapy for IFD. A total of 299 samples (63 %) were obtained during the administration of the intravenous form of VRC. The median VRC daily dose based on the actual body weight was 6.68 mg/kg/day (range, 1.92-10.41 mg/kg/day). The median VRC trough level was 0.99 mg/l (range, <0.09-5.45 mg/l). The multivariate analysis using a logistic regression model demonstrated significantly higher VRC trough levels (≥1.0 mg/l) in males (P < 0.001), empirical or preemptive therapy (P = 0.002), VRC daily dose based on the actual body weight ≥7 mg/kg/day (P < 0.001), and concomitant use of lansoprazole as compared to rabeprazole (P < 0.001). The concomitant use of calcineurin inhibitors and corticosteroids had no effects on VRC trough levels in multivariate analysis. These data suggest that lansoprazole and rabeprazole have different effects on the plasma VRC trough levels in the allogeneic HCT recipients.

Rhabdomyolysis associated with single-dose intravenous esomeprazole administration: A case report

BACKGROUND

Proton pump inhibitors are usually safe, although serious adverse effects can occur. We report the first case of rhabdomyolysis associated with single-dose intravenous esomeprozole administration.

METHODS

A 45-year-old Korean male visited our emergency room because of persistent lower chest discomfort that started 10 hours before. He had been diagnosed with diabetes and coronary heart disease, but discontinued oral hypoglycemic agents 1 month earlier. He continued to take medications for coronary heart disease. There was no abnormality on an electrocardiogram or in cardiac enzymes. Initial laboratory findings did not show abnormalities for muscle enzymes. Esomeprozole 40 mg was administrated intravenously for the control of his ambiguous chest discomfort. Then, 12 hours later, he complained of abrupt severe right buttock pain. An area of tender muscle swelling 8 cm in diameter was seen on his right buttock area. Creatine kinase and lactate dehydrogenase were elevated to 40,538 and 1326 U/L, respectively. A bone scan using 20 mCi of Tc-hydroxymethylene diphosphonate was compatible with rhabdomyolysis.

RESULTS

His muscular symptoms, signs, and laboratory findings improved markedly with conservative management, including hydration and urine alkalinization. He is being followed in the outpatient department with no evidence of recurrence.

CONCLUSION

We should keep in mind that single-dose intravenous administration of esomeprazole can induce rhabdomyolysis.

Proton pump inhibitor co-prescription with dual antiplatelet therapy among patients with acute coronary syndrome in Qatar

BACKGROUND

There are increasing concerns about clinically significant interactions between proton pump inhibitors (PPIs) and clopidogrel, resulting in adverse cardiovascular outcomes in patients with acute coronary syndromes (ACS). However, published evidence on the prevalence and predictors of PPI use with dual antiplatelet therapy (DAPT) is scarce.

OBJECTIVE

This study investigated the prevalence of PPI use among patients with ACS receiving DAPT and possible predictors of co-prescribing the PPIs with the DAPT.

SETTING

Heart Hospital, a specialized tertiary care center in Qatar.

METHODOLOGY

A retrospective observational study of a prescription database was conducted. Subjects included 626 patients admitted between January and December 2012 with the diagnosis of ACS who received DAPT and discharged with or without a PPI. Univariate analysis and multivariate binary logistic regression analysis were performed to determine the predictors of PPI-DAPT co-prescription.

MAIN OUTCOME MEASURES

Prevalence of PPI co-prescribing with DAPT in proportions and percentages and odd ratios for the predictors of PPI-DAPT co-prescribing.

RESULTS

A total of 626 patients were analyzed for PPI prevalence, with 200 patients (32 %) being prescribed PPI with DAPT upon discharge. After controlling for confounders, PPI use on admission (aOR 14.5; 95 % CI 7.6-27.6, p < 0.001), nationality (aOR 3.2; 95 % CI 1.1-9.9, p = 0.041), and having a history of diabetes (aOR 0.5; 95 % CI 0.24-0.99, p = 0.046) significantly influenced PPI-DAPT co-prescribing. Users of PPI on admission compared to nonusers were about 15 times more likely to be prescribed PPI with DAPT upon discharge; likewise, having Qatari nationality increased the likelihood of co-prescribing PPI with DAPT upon discharge by three folds. Lastly, patients with a history of diabetes were 50 % less likely to be prescribed PPIs upon discharge compared to those with no history of diabetes.

CONCLUSION

The rate of PPI co-prescribing with DAPT in the population studied was relatively high. The strongest predictor of PPI co-prescription with DAPT upon discharge was PPI use on admission. Furthermore, PPI prescribing was significantly predicted by nationality and not having diabetes. Further studies are warranted to better predict the factors associated with PPI-DAPT co-prescription and to investigate rational prescribing of PPIs among ACS patients.

Proton Pump Inhibitors in Cardiovascular Disease: Drug Interactions with Antiplatelet Drugs

Aspirin and P2Y₁₂ receptor antagonists are widely used across the spectrum of cardiovascular diseases. Upper gastrointestinal complications, including ulcer and bleeding, are relatively common during antiplatelet treatment and, therefore, concomitant proton pump inhibitor (PPI) treatment is often prescribed.PPIs provide gastroprotection by changing the intragastric milieu, essentially by raising intragastric pH. In recent years, it has been heavily discussed whether PPIs may reduce the cardiovascular protection by aspirin and, even more so, clopidogrel. Pharmacodynamic and pharmacokinetic studies suggested an interaction between PPIs and clopidogrel, and subsequent clinical studies were conducted to evaluate the clinical impact of this interaction. More recently, it was reported that PPIs may also attenuate the antiplatelet effect of aspirin. This may be clinically important, because a fixed combination of aspirin and a PPI (esomeprazole) has recently been approved and because aspirin is the most widely used drug in patients with cardiovascular disease. The antiplatelet effect of the new P2Y₁₂ receptor antagonists, ticagrelor and prasugrel, seems less influenced by PPI co-treatment.Given the large number of patients treated with antithrombotic drugs and PPIs, even a minor reduction of platelet inhibition potentially carries considerable clinical impact. The present book chapter summarizes the evidence regarding the widespread use of platelet inhibitors and PPIs in combination. Moreover, it outlines current evidence supporting or opposing drug interactions between these drugs and discusses clinical implications.

Acid suppression therapy and allergic reactions

The development of pharmaceutical agents such as sucralfate, histamine 2 (H2) receptor blockers and proton pump inhibitors (PPIs) reducing gastric acidity has been a mile stone for treatment of dyspeptic disorders. However, due to current prescription habits resulting in overuse of these potent drugs as well as over-the-counter (OTC) availability associated with self-medication, substantial health concern is related to the mechanisms of drug action as well as known side effects influencing gastrointestinal physiology. More than a decade ago the first study appeared reporting an association between anti-ulcer drug intake and food allergy development. Ever since this first report several experimental as well as human studies verified this correlation, demonstrating that acid suppressive drugs not only influence the sensitization capacity of orally ingested proteins, but also represent a risk factor for food allergy patients. Additionally, gastric acid suppression was reported to increase the risk for development of drug hypersensitivity reactions. These consequences of anti-ulcer drug intake might on the one hand be associated with direct influence of these drugs on immune responses. On the other hand reduction of gastric acidity leads to impaired gastrointestinal protein degradation. Nevertheless, also disruption of the gastrointestinal barrier function, changes in microbiome or lack of tolerogenic peptic digests might contribute to the connection between anti-ulcer drug intake and allergic reaction. Therefore, these drugs should only be prescribed based on a precise gastroenterological diagnosis taking into consideration allergological mechanisms to ensure patients' safety.

Dexlansoprazole - a new-generation proton pump inhibitor

Dexlansoprazole modified release (MR) is an R-enantiomer of lansoprazole and a new-generation proton pump inhibitor exhibiting high efficacy in the treatment of symptoms and lesions associated with erosive oesophagitis caused by gastroesophageal reflux disease (GERD). The dual release of the active ingredient - in the duodenum and the small intestine - makes it possible to achieve two peak concentrations at various times, within two and five hours of administration. Dexlansoprazole MR ensures the longest maintenance of drug concentration in the plasma of all known proton pump inhibitors, and the longest proton pump inhibitory effect. The basic indications for the drug include all forms of gastroesophageal reflux disease, especially with night-time heartburn and sleep disorders resulting from GERD. Dexlansoprazole can be taken regardless of meal times. It has a good safety profile and carries a low risk of adverse interactions with other drugs.

Pantoprazole inhibits human gastric adenocarcinoma SGC-7901 cells by downregulating the expression of pyruvate kinase M2

The Warburg effect is important in tumor growth. The human M2 isoform of pyruvate kinase (PKM2) is a key enzyme that regulates aerobic glycolysis in tumor cells. Recent studies have demonstrated that PKM2 is a potential target for cancer therapy. The present study investigated the effects of pantoprazole (PPZ) treatment and PKM2 transfection on human gastric adenocarcinoma SGC-7901 cells in vitro. The present study revealed that PPZ inhibited the proliferation of tumor cells, induced apoptosis and downregulated the expression of PKM2, which contributes to the current understanding of the functional association between PPZ and PKM2. In summary, PPZ may suppress tumor growth as a PKM2 protein inhibitor.

Recognizing off-target drug effects in the gut and brain: revisiting isotretinoin and depression

Clinicians often face complex decisions regarding off-target drug effects, both in diagnosis and treatment. A key component in the formulation of the correct diagnosis is the temporal relationship between drug introduction and adverse effect. The sentinel injury may target the gut and brain. The description of the complaint may vary among providers. Modeling Information visualization for clinicians in real time will require the integration of time-stamped data with organ-specific complaints.

The potential drug-drug interaction between proton pump inhibitors and warfarin

BACKGROUND

Proton pump inhibitors (PPIs) have been suggested to increase the effect of warfarin, and clinical guidelines recommend careful monitoring of international normalized ratio (INR) when initiating PPI among warfarin users. However, this drug-drug interaction is sparsely investigated in a clinical setting. The aim was to assess whether initiation of PPI treatment among users of warfarin leads to increased INR values.

METHODS

The study was an observational self-controlled study from 1998 to 2012 leveraging data on INR measurements on patients treated with warfarin from primary care and outpatient clinics and their use of prescription drugs. Data were analyzed in 2015. We assessed INR, warfarin dose, and dose/INR ratio before and after initiating PPI treatment using the paired student's t-test.

RESULTS

We identified 305 warfarin users initiating treatment with PPIs. The median age was 71 years (interquartile range 63-78 years), and 64% were men. The mean INR in the 70 days prior to PPI initiation was 2.6 (95%CI 2.5-2.8) and 2.6 (95%CI 2.5-2.7) in the period 1-3 weeks after PPI initiation (p = 0.67). Further, neither mean warfarin dose nor the dose/INR ratios were significantly different before and after PPI initiation. Sensitivity analyses revealed no differences among individual PPIs.

CONCLUSIONS

We found no evidence of a clinically meaningful drug-drug interaction between PPIs and warfarin in a Northern European patient population of unselected patients from an everyday outpatient and primary care clinical setting. Thus, we do not support the recommendation to "cautiously monitor" users of warfarin initiating PPI treatment.

Proton pump inhibitors do not impair the effectiveness of metformin in patients with diabetes

AIMS

In order to exert its pharmacodynamic effect, the diabetes drug metformin needs to be taken up into hepatocytes by the organic cation transporter (OCT) system. A recent in vitro study found that proton pump inhibitors (PPIs) inhibit OCT1, OCT2 and OCT3, suggesting that PPIs might reduce metformin's effectiveness. This pharmacoepidemiologic study looked for evidence of a clinical effect of such an interaction.

METHODS

This was an observational cohort study examining changes in glycosylated haemoglobin (HbA1c) with exposure to metformin and to PPIs as single agents and in combination. The aim was to assess evidence of a deleterious drug-drug interaction.

RESULTS

PPIs did not reduce the effectiveness of metformin, and indeed were associated with a minimally better glycaemic response by - 0.06 HbA1c percentage points (95% confidence interval, -0.10, -0.01) in metformin initiators.

CONCLUSIONS

Despite a mechanistic basis for a potential drug-drug interaction, we found no evidence of a deleterious interaction between PPIs and metformin.

Pharmacokinetic drug interaction profiles of proton pump inhibitors: an update

Proton pump inhibitors (PPIs) are used extensively for the treatment of gastric acid-related disorders, often over the long term, which raises the potential for clinically significant drug interactions in patients receiving concomitant medications. These drug–drug interactions have been previously reviewed. However, the current knowledge is likely to have advanced, so a thorough review of the literature published since 2006 was conducted. This identified new studies of drug interactions that are modulated by gastric pH. These studies showed the effect of a PPI-induced increase in intragastric pH on mycophenolate mofetil pharmacokinetics, which were characterised by a decrease in the maximum exposure and availability of mycophenolic acid, at least at early time points. Post-2006 data were also available outlining the altered pharmacokinetics of protease inhibitors with concomitant PPI exposure. New data for the more recently marketed dexlansoprazole suggest it has no impact on the pharmacokinetics of diazepam, phenytoin, theophylline and warfarin. The CYP2C19-mediated interaction that seems to exist between clopidogrel and omeprazole or esomeprazole has been shown to be clinically important in research published since the 2006 review; this effect is not seen as a class effect of PPIs. Finally, data suggest that coadministration of PPIs with methotrexate may affect methotrexate pharmacokinetics, although the mechanism of interaction is not well understood. As was shown in the previous review, individual PPIs 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 sodium (pantoprazole-Na) have been studied most extensively. Several studies have shown that omeprazole carries a considerable potential for drug interactions because of its high affinity for CYP2C19 and moderate affinity for CYP3A4. In contrast, pantoprazole-Na appears to have lower potential for interactions with other medications. Lansoprazole and rabeprazole also seem to have a weaker potential for interactions than omeprazole, although their interaction profiles, along with those of esomeprazole and dexlansoprazole, have been less extensively investigated. Only a few drug interactions involving PPIs are of clinical significance. Nonetheless, the potential for drug interactions should be considered when choosing a PPI to manage gastric acid-related disorders. This is particularly relevant for elderly patients taking multiple medications, or for those receiving a concomitant medication with a narrow therapeutic index.

Concomitant drugs with low risks of drug-drug interactions for use in oncology clinical trials

BACKGROUND

Drug-drug interactions (DDIs) may occur with investigational drugs and affect patient safety, trial outcomes, and drug development. A list of preferred drugs with minimal risks of DDIs for treatment of symptoms or comorbidities frequently encountered by cancer patients would be helpful.

METHODS

We reviewed the literature to assess DDIs reported for the main drugs available for treatment of symptoms/comorbidities frequently encountered by cancer patients. Reviews and relevant original articles cited were retrieved and analyzed, and the following data were collected and double-checked: pharmacological properties; effects, if any, of drugs on CYP enzymes, membrane transporters, and QT interval; and involvement in significant DDIs.

RESULTS

A list of preferred drugs with minimal risks of DDIs was compiled.

CONCLUSION

Acknowledging for heterogeneity in data sources, prevention of unexpected DDIs during clinical trials may be improved by using this list of preferred drugs for the management of study patient's symptoms.

[Effect of drug interaction between clopidogrel and omeprazole in hospital readmision of patients by a recurrent acute coronary syndrome: a case-control study]

Objetivo

Evaluar el efecto de la interacción clopidogrel-omeprazol en el reingreso hospitalario de pacientes por recidiva de síndrome coronario agudo (SCA)

Diseño

Estudio de casos y controles

Emplazamiento

IPS Universitaria Clínica León XIII, Medellín, Colombia.

Participantes

Se seleccionaron a partir de una población prevalente, entre 2009-2010, pacientes con uso de clopidogrel de forma ambulatoria (menor a un año y superior a 30 días), y la estancia hospitalaria por un SCA o la presencia de un SCA previo.

Medidas principales

Un paciente-caso se definió como aquel que presentó una recidiva de SCA y un paciente-control se definió como aquel que no presentó recidiva de SCA. Ambos grupos utilizaron ambulatoriamente clopidogrel debido al SCA previo. Como factor de riesgo se definió la utilización conjunta de omeprazol y clopidogrel ambulatoriamente.

Resultados

Durante el estudio se formuló clopidogrel a 1.680 pacientes. En este grupo se identificaron 50 casos readmitidos con SCA y 76 controles. No se encontró asociación estadísticamente significativa entre el uso de clopidogrel-omeprazol y un mayor riesgo de reingreso hospitalario por SCA (OR: 1,05; IC 95%: 0,516-2,152; p = 0,8851).

Conclusiones

En este pequeño grupo de pacientes con SCA previo, la utilización simultánea de clopidogrel con omeprazol no aumenta el riesgo de un reingreso hospitalario por recurrencia de este tipo de evento coronario.

The pharmacokinetics of conventional and bioenhanced tablet formulations of danirixin (GSK1325756) following oral administration in healthy, elderly, human volunteers

Danirixin (GSK1325756) is a small, high-affinity, selective and reversible CXCR2 antagonist in development for treatment of chronic obstructive pulmonary disease. The objective of the study was to evaluate the relative bioavailability, including the inter-subject variability, of a conventional immediate-release (IR) formulation and two prototype bioenhanced formulations of danirixin during gastric acid suppression in a healthy, elderly population. A single-centre, crossover study in healthy male and female volunteers aged 65–80 years was conducted. Subjects were randomised to receive danirixin 50 mg IR in the fed and fasted states and danirixin 50 mg Bioenhanced Formulation 1 and 2 in the fasted state. All subjects also received omeprazole 20 mg each morning beginning 4 days prior to the first treatment period and continuing through danirixin dosing in the final treatment period. Twenty subjects were randomised and completed the study. Bioenhanced Formulation 2 in the fasted state demonstrated the highest adjusted geometric means for AUC_(0–t), AUC_(0–inf), AUC_(0–24) and C_max. Danirixin IR demonstrated adjusted means that were higher in the fed state compared with the fasted state. For all formulations tested, there was substantial inter-subject variability (CVb >100 % for all formulations). The overall incidences of adverse events (AEs) were 10 % for danirixin IR (both in the fed and fasted states) and 15–20 % for the bioenhanced formulations. The majority of AEs were mild in intensity. There were no serious AEs. Concomitant use of omeprazole resulted in large inter-subject variability in the exposure to danirixin. Bioenhanced formulation strategies could not overcome the effect of omeprazole on exposure and variability between subjects.

Proton pump inhibitors and clopidogrel: an association to avoid?

Dual antiplatelet therapy with aspirin and clopidogrel reduces cardiovascular events following an acute coronary syndrome or stent implantation, but the associated increased risk of gastro-intestinal bleeding often leads to the co-administration of proton pump inhibitors (PPIs). PPIs have been shown to decrease antiplatelet effects of clopidogrel ex vivo, raising concerns about the cardiovascular safety of this drug combination. Clinical trials investigating PPI-clopidogrel interactions have provided conflicting results and are all subject to methodological critiques. The much desired and much needed prospective, double-bind, randomized, placebo-controlled trials with adequate follow-up and sample size have not yet been performed. Indeed, the Clopidogrel and the Optimization of GI Events Trial, which would have had such characteristics, was stopped prematurely. As a consequence, the question of the PPI-clopidogrel interaction is still unresolved, and clinical consequences cannot be excluded. At this time such combination therapy should, therefore, be provisionally advocated only for patients at high risk of bleeding (prior upper gastro-intestinal bleeding, advanced age, concomitant use of warfarin, steroidal or non-steroidal anti-inflammatory drugs and Helicobacter pylori infection) and avoiding PPIs with strong affinity for cytochrome CYP2C19, such as omeprazole and esomeprazole.

Effect of meal and antisecretory agents on the pharmacokinetics of danoprevir/ritonavir in healthy volunteers

OBJECTIVES

To evaluate the effect of a low- and high-fat meal and co-administration of ranitidine or omeprazole on the pharmacokinetics of ritonavir-boosted danoprevir (DNVr).

METHODS

In this randomised, open-label, cross-over study, healthy subjects received a single dose of DNVr. In group 1, DNVr was administered while fasting or with a low-fat or high-fat meal. In group 2, DNVr was administered alone or with ranitidine 150 mg (single dose) or omeprazole 40 mg (multiple doses).

KEY FINDINGS

Group 1 (n = 16): relative to fasting conditions, food slightly prolonged absorption but did not alter the extent of absorption. DNV area under the plasma concentration-time curve extrapolated to infinity (AUC0-∞), maximum plasma concentration (C(max)), and plasma concentration 12 h after administration (C12h) geometric mean ratios (GMR%) (90% confidence interval (CI)) with a low-fat meal were 92.3 (80.2-106), 61.8 (51.0-74.9) and 95.2 (80.9-112), versus fasting conditions, and with a high-fat meal 99.5 (86.4-115), 58.9 (48.5-71.6) and 101 (86.0-119). Group 2 (n = 13): ranitidine or omeprazole had no clinically significant effect on DNV pharmacokinetics. DNV AUC0-∞, Cmax and C12h GMR% (90% CI) with ranitidine: 81.9 (68.3-98.1), 104 (86.9-123) and 87.5 (69.3-111), and with omeprazole: 83.0 (67.4-102), 92.7 (70.6-122) and 93.3 (65.6-133).

CONCLUSIONS

The absence of clinically relevant effects of food, ranitidine or omeprazole on DNVr pharmacokinetics suggests that DNVr can be administered without regard to meals and in combination with H2 antagonists or proton pump inhibitors.

Pharmacokinetic drug interaction profile of omeprazole with adverse consequences and clinical risk management

BACKGROUND

Omeprazole, a proton pump inhibitor (PPI), is widely used for the treatment of dyspepsia, peptic ulcer, gastroesophageal reflux disease, and functional dyspepsia. Polypharmacy is common in patients receiving omeprazole. Drug toxicity and treatment failure resulting from inappropriate combination therapy with omeprazole have been reported sporadically. Systematic review has not been available to address the pharmacokinetic drug-drug interaction (DDI) profile of omeprazole with adverse consequences, the factors determining the degree of DDI between omeprazole and comedication, and the corresponding clinical risk management.

METHODS

Literature was identified by performing a PubMed search covering the period from January 1988 to March 2013. The full text of each article was critically reviewed, and data interpretation was performed.

RESULTS

Omeprazole has actual adverse influences on the pharmacokinetics of medications such as diazepam, carbamazepine, clozapine, indinavir, nelfinavir, atazanavir, rilpivirine, methotrexate, tacrolimus, mycophenolate mofetil, clopidogrel, digoxin, itraconazole, posaconazole, and oral iron supplementation. Meanwhile, low efficacy of omeprazole treatment would be anticipated, as omeprazole elimination could be significantly induced by comedicated efavirenz and herb medicines such as St John's wort, Ginkgo biloba, and yin zhi huang. The mechanism for DDI involves induction or inhibition of cytochrome P450, inhibition of P-glycoprotein or breast cancer resistance protein-mediated drug transport, and inhibition of oral absorption by gastric acid suppression. Sometimes, DDIs of omeprazole do not exhibit a PPI class effect. Other suitable PPIs or histamine 2 antagonists may be therapeutic alternatives that can be used to avoid adverse consequences. The degree of DDIs associated with omeprazole and clinical outcomes depend on factors such as genotype status of CYP2C19 and CYP1A2, ethnicity, dose and treatment course of precipitant omeprazole, pharmaceutical formulation of object drug (eg, mycophenolate mofetil versus enteric-coated mycophenolate sodium), other concomitant medication (eg, omeprazole-indinavir versus omeprazole-indinavir-ritonavir), and administration schedule (eg, intensified dosing of mycophenolate mofetil versus standard dosing).

CONCLUSION

Despite the fact that omeprazole is one of the most widely prescribed drugs internationally, clinical professionals should enhance clinical risk management on adverse DDIs associated with omeprazole and ensure safe combination use of omeprazole by rationally prescribing alternatives, checking the appropriateness of physician orders before dispensing, and performing therapeutic drug monitoring.

Stress ulcer prophylaxis in non-critically ill patients: a prospective evaluation of current practice in a general surgery department

RATIONALE, AIMS AND OBJECTIVES

There is little evidence regarding the benefit of stress ulcer prophylaxis (SUP) outside a critical care setting. Overprescription of SUP is not devoid of risks. This prospective study aimed to evaluate the use of proton pump inhibitors (PPIs) for SUP in a general surgery department.

METHOD

Data collection was performed prospectively during an 8-week period on patients hospitalized in a general surgery department (58 beds) by pharmacists. Patients with a PPI prescription for the treatment of ulcers, gastro-oesophageal reflux disease, oesophagitis or epigastric pain were excluded. Patients admitted twice during the study period were not reincluded. The American Society of Health-System Pharmacists guidelines on SUP were used to assess the appropriateness of de novo PPI prescriptions.

RESULTS

Among 255 patients in the study, 138 (54%) received a prophylaxis with PPI, of which 86 (62%) were de novo PPI prescriptions. A total of 129 patients (94%) received esomeprazole (according to the hospital drug policy). The most frequent dosage was at 40 mg once daily. Use of PPI for SUP was evaluated in 67 patients. A total of 53 patients (79%) had no risk factors for SUP. Twelve and two patients had one or two risk factors, respectively. At discharge, PPI prophylaxis was continued in 33% of patients with a de novo PPI prescription.

CONCLUSIONS

This study highlights the overuse of PPIs in non-intensive care unit patients and the inappropriate continuation of PPI prescriptions at discharge. Treatment recommendations for SUP are needed to restrict PPI use for justified indications.

Clopidogrel and the possibility of drug-drug interaction in primary health care

INTRODUCTION

Clopidogrel ineffectiveness is a serious problem in antiplatelet therapy. Many factors may contribute to this phenomenon. One of them is clopidogrel drug-drug interaction with CYP2C19 and CYP3A4 enzyme inhibitors. The main goal of this descriptive study was to assess the prevalence of cases of clopidogrel-drug interactions in the primary health care physicians' practices.

MATERIALS AND METHODS

During 2010-2011, 80 patients receiving clopidogrel antiplatelet therapy from primary care physicians' clinical practices were involved in this study. By using questionnaires and case histories, the following information was collected: Age, gender, clinical diagnoses, and medications used.

RESULTS

IN THE CURRENT STUDY, DRUGS WERE USED THAT COULD POTENTIALLY INFLUENCE THE EFFECT OF CLOPIDOGREL: Omeprazole, lipophilic statins, calcium channel blockers (CCB). There was a different use of the above-mentioned drugs before and after the initiation of the clopidogrel therapy, e.g., 12 (15.0%) and 44 (55.0%) patients used proton pump inhibitors (PPI) before and after the clopidogrel therapy accordingly (P = 0.16; χ (2) = 1.91). However, pantoprazole was recommended more often than other PPI. The use of the potential CYP3A4 inhibitors - lipophilic statins and CCB - was increased after the prescription of clopidogrel too. Concomitant use of statins (mainly atorvastatin) with clopidogrel was observed in 75 (93.8%) patients and the use of CCB (mainly amlodipine) - in 33 (41.3%) patients.

CONCLUSION

In the primary health care practices, it is revealed that there is co-medication of clopidogrel with weak CYP3A4 inhibitors, such as lipophilic statins and amlodipine, and with the moderate CYP2C19 inhibitor - omeprazole. The latter co-medication is potentially harmful and it is very important to inform the first care professionals about the opportunity to change omeprazole to pantoprazole, which does not influence clopidogrel biotransformation.

Role of CYP450 in Antiplatelet Therapy: Considerations for Patients at Risk for Further Cardiovascular or Cerebrovascular Problems

Objective:

To determine how interactions with cytochrome P450 ( CYP450) isoenzyme pathways may influence the selection of antiplatelet therapy in patients with cardiovascular and cerebrovascular disease.

Data Sources:

A MEDLINE search (1966-September 2012) was performed using the following MeSH search terms: clopidogrel, prasugrel, ticagrelor, aspirin, dipyridamole, drug interactions, polymorphism, cytochrome P450, platelets, platelet reactivity testing, and platelet function. In addition, reference citations were reviewed.

Study Selection and Data Extraction:

Selected studies analyzed the effects of CYP450 isoenzymes on the efficacy of antiplatelet therapy and potential drug-drug interactions.

Data Synthesis:

Antiplatelet therapy is pivotal in reducing the risk of acute coronary syndromes. Thienopyridines are commonly prescribed for antiplatelet drug therapy; however, a multitude of factors can influence their efficacy, given that thienopyridines require activation through CYP450 isoenzymes. Genetic polymorphisms in CYP450 isoenzymes and the susceptibility of drug-drug interactions mediated through the CYP450 system have led to variability in antiplatelet response. Two factors in particular have been prime targets in elucidating the role of CYP450 isoenzymes on thienopyridine activity and bioavailability: CYP2C19*2 polymorphisms and drug interactions with proton pump inhibitors. Additionally, many studies have surfaced in an attempt to quantify a patient's response to antiplatelet therapy but, to date, none has determined whether platelet reactivity testing is mandatory prior to initiation of therapy or whether it correlates with clinical efficacy. This review spotlights the pharmacokinetic and pharmacodynamic influences that CYP450 isoenzymes exert on antiplatelet therapies and attempts to categorize the role of platelet reactivity testing in determining the clinical significance of drug interactions.

Conclusions:

Suboptimal responses to antiplatelet therapy may occur because of interactions with CYP450 isoenzyme pathways. Further studies are warranted to clarify the impact of genetic polymorphisms and drug-drug interactions on clinical outcomes in patients with cardiovascular/cerebrovascular disease.

Effects of pantoprazole on dual antiplatelet therapy in stable angina pectoris patients after percutaneous coronary intervention

BACKGROUND

Our aim was to prospectively assess the potential influence of pantoprazole therapy on the antiplatelet effects of acetylsalicylic acid (ASA) and clopidogrel (CLO) in stable angina pectoris (SAP) patients after percutaneous coronary intervention (PCI).

METHODS

Forty-four patients with SAP (CCS I-III) and successful PCI with stent implantation were enrolled into the study. The patients were divided into group proton pump inhibitors (PPI): 23 patients with indications for PPI (F/M = 9/14; age = 64 ± 9; standard therapy + 20 mg pantoprazole) and the control group (group C): 21 patients (F/M = 6/15; age = 64 ± 8; standard therapy). The platelet function analysis in whole blood based on impedance aggregometry (ASPI, COL, ADP, TRAP tests) using Multiplate--V2.02.11 was performed 18-24 h after the PCI + CLO loading dose (600 mg) and 30 days after PCI.

RESULTS

Both baseline patient characteristics and clinical outcomes were comparable between the study groups. There were no differences in the mean values of the platelets (PTL) tests measured at the 30(th) day after PCI between both groups (PPI vs. C: ASPI: 24.6 ± 10.0 vs. 42.1 ± 14.8 U, COL: 32.9 ± 8.6 vs. 34.0 ± 7.7 U, ADP: 26.8 ± 12.4 vs. 30.4 ± 8.1 U, TRAP: 78.7 ± 16.6 vs. 78.1 ± 22.6 U, p = ns). The mean delta values of the PTL tests (18-24 h post-PCI/30 days post-PCI) were also comparable between the groups. The PTL aggregometry results were related to time (ADP, ASPI, TRAP vs. time, p = 0.001; COL vs. time, p = 0.03)--the baseline values of ADP, ASPI, COL and TRAP tests were smaller than those measured after the one-month observation.

CONCLUSION

Pantoprazole treatment does not impair the efficacy of dual antiplatelet therapy in patients with SAP after PCI.

Impact of clinical pharmacy services on stress ulcer prophylaxis prescribing and related cost in patients with renal insufficiency

Objectives

Compared to the general population, chronic kidney disease patients are more vulnerable to gastrointestinal haemorrhage and its morbidity and mortality. Due to the fear of gastrointestinal bleeding consequences in these patients on the one hand, and the perception of general safety of acid suppressive medications on the other hand, inappropriate stress ulcer prophylaxis (SUP) seems to be encountered in nephrology wards. The objectives of this study were to evaluate appropriateness of acid suppression therapy in kidney disease patients and to assess the role of clinical pharmacists to decrease inappropriate SUP prescribing and related costs for these patients.

Methods

All inpatients at nephrology wards of a teaching hospital were assessed regarding appropriate SUP prescribing during a 6-month pre-intervention phase of the study without any clinical pharmacists' involvement in patients' management. Thereafter, during a 6-month post-intervention phase clinical pharmacists provided local SUP protocol and educational classes for physicians regarding appropriate SUP prescribing and participated actively in the patient-care team.

Main findings

The results showed significant relative reduction in inappropriate SUP prescribing and related cost in patients with renal insufficiency by about 44% and 67% respectively.

Conclusion

This study showed that implementing institutional guidelines, and active involvement of clinical pharmacists in the nephrology healthcare team, could reduce inappropriate SUP prescribing and related costs for these patients.

DUEXIS(®) (ibuprofen 800 mg, famotidine 26.6 mg): a new approach to gastroprotection for patients with chronic pain and inflammation who require treatment with a nonsteroidal anti-inflammatory drug

Chronic pain conditions affect at least 116 million US adults and more than one-third of adults worldwide. Nonsteroidal anti-inflammatory drugs (NSAIDs) are used extensively for the treatment of chronic pain due to their efficacy as anti-inflammatory and analgesic agents. Gastrointestinal toxicity is the most well known adverse effect of NSAID therapy and it may manifest as dyspepsia, ulcers, or bleeding. Current guidelines for the management of patients who require NSAIDs for chronic pain and inflammation recognize the potential toxicity associated with these drugs and the need for gastroprotection. DUEXIS(®) (ibuprofen 800 mg, famotidine 26.6 mg) is a proprietary combination, immediate release tablet containing 800 mg of ibuprofen and 26.6 mg of famotidine. The efficacy of DUEXIS(®) taken three times daily has been demonstrated in two large-scale controlled clinical trials (Registration Endoscopic Studies to Determine Ulcer Formation of HZT-501 Compared with Ibuprofen: Efficacy and Safety Studies (REDUCE) and REDUCE-2) which showed that this new formulation significantly reduced the risk of endoscopic upper gastrointestinal ulcers compared with ibuprofen alone (REDUCE-1, p < 0.0001, REDUCE-2, p <0.05). DUEXIS(®) was also superior to ibuprofen in decreasing the risk for gastric ulcers (REDUCE-1, p < 0.001, REDUCE-2, p < 0.05) as well as duodenal ulcers (REDUCE-1, p < 0.05, REDUCE-2, p < 0.05). Safety results from these two studies indicated that treatment-emergent adverse events occurred in 55% of patients treated with DUEXIS(®)versus 58.7% for ibuprofen, and serious adverse events were recorded for 3.2% of patients treated with DUEXIS(®)versus 3.3% of those on ibuprofen. Adverse events leading to discontinuation occurred in 6.7% of patients treated with DUEXIS(®) and 7.6% for ibuprofen. The combination of ibuprofen and famotidine in a single tablet has the potential to improve adherence to gastroprotective therapy in patients who require NSAID treatment and the use of a histamine type 2 receptor antagonist rather than a proton-pump inhibitor may decrease the risk for clinically significant drug interactions and adverse events (e.g. interaction with clopidogrel, fracture, pneumonia, Clostridium difficile infection).

Evaluation of six proton pump inhibitors as inhibitors of various human cytochromes P450: focus on cytochrome P450 2C19

Six proton pump inhibitors (PPIs), omeprazole, lansoprazole, esomeprazole, dexlansoprazole, pantoprazole, and rabeprazole, were shown to be weak inhibitors of cytochromes P450 (CYP3A4, -2B6, -2D6, -2C9, -2C8, and -1A2) in human liver microsomes. In most cases, IC₅₀ values were greater than 40 μM, except for dexlansoprazole and lansoprazole with CYP1A2 (IC₅₀ = ∼8 μM) and esomeprazole with CYP2C8 (IC₅₀ = 31 μM). With the exception of CYP2C19 inhibition by omeprazole and esomeprazole (IC₅₀ ratio, 2.5 to 5.9), there was no evidence for a marked time-dependent shift in IC₅₀ (IC₅₀ ratio, ≤ 2) after a 30-min preincubation with NADPH. In the absence of preincubation, lansoprazole (IC₅₀ = 0.73 μM) and esomeprazole (IC₅₀ = 3.7 μM) were the most potent CYP2C19 inhibitors, followed by dexlansoprazole and omeprazole (IC₅₀ = ∼7.0 μM). Rabeprazole and pantoprazole (IC₅₀ = ≥ 25 μM) were the weakest. A similar ranking was obtained with recombinant CYP2C19. Despite the IC₅₀ ranking, after consideration of plasma levels (static and dynamic), protein binding, and metabolism-dependent inhibition, it is concluded that omeprazole and esomeprazole are the most potent CYP2C19 inhibitors. This was confirmed after the incubation of the individual PPIs with human primary hepatocytes (in the presence of human serum) and by monitoring their impact on diazepam N-demethylase activity at a low concentration of diazepam (2 μM). Data described herein are consistent with reports that PPIs are mostly weak inhibitors of cytochromes P450 in vivo. However, two members of the PPI class (esomeprazole and omeprazole) are more likely to serve as clinically relevant inhibitors of CYP2C19.

Absorption, distribution, metabolism and excretion of [14C]dexlansoprazole in healthy male subjects

BACKGROUND AND OBJECTIVE

The proton pump inhibitor dexlansoprazole is a modified-release formulation of dexlansoprazole, an enantiomer of lansoprazole, which employs a Dual Delayed Release™ (DDR) delivery system. This study was conducted in healthy subjects to assess the absorption, distribution, metabolism and excretion of a 60 mg dose of [14C]dexlansoprazole.

METHODS

After multiple daily doses of dexlansoprazole DDR for 4 days followed by a single dose of [14C]dexlansoprazole on day 5, absorption, distribution, metabolism and elimination of [14C]dexlansoprazole were assessed in six healthy male subjects whose CYP (cytochrome P450) 2C19 metabolizer status was also determined.

RESULTS

Five subjects were phenotyped as extensive metabolizers (EMs) and one subject was a poor metabolizer (PM). Recovery of radioactivity in urine and faeces averaged 98% after 7 days (51% in urine and 48% in faeces) post-14C dosing. In plasma, dexlansoprazole was the largest component detected, with the main metabolites in the EM subjects being 5-glucuronyloxy dexlansoprazole and 5-hydroxy dexlansoprazole (CYP2C19 mediated), whereas the PM subject had greater amounts of dexlansoprazole sulfone (CYP3A mediated). Dexlansoprazole was not detected in urine; six metabolites were identified accounting for an average of 86% of the urinary radioactivity, with 5-glucuronyloxy dexlansoprazole, 5-glucuronyloxy dexlansoprazole sulfide, 2-S-N-acetylcysteinyl benzimidazole and 5-sulfonyloxy dexlansoprazole sulfide being the primary metabolites. In faeces, parent drug and six identified metabolites accounted for 23% and 72%, respectively, of the faecal radioactivity, with 5-hydroxy dexlansoprazole sulfide and dexlansoprazole sulfide being predominant.

CONCLUSION

Overall, the results indicate that [14C]dexlansoprazole was well absorbed and extensively metabolized by oxidation, reduction and conjugation to 13 identified metabolites.

Multicenter study of voriconazole pharmacokinetics and therapeutic drug monitoring

Voriconazole is a first-line agent in the treatment of many invasive fungal infections and is known to display highly variable pharmacokinetics. Previous studies of voriconazole therapeutic drug monitoring (TDM) have suggested concentration monitoring to be clinically useful but have been limited by small patient samples at a single institution. This multicenter retrospective study aimed to investigate relationships between voriconazole concentration and clinical outcomes and adverse events and to assess clinical factors and drug interactions that may affect voriconazole concentration. Medical records were reviewed for patients who received voriconazole and had at least 1 concentration measured at seven hospitals in Australia. The study included 201 patients with 783 voriconazole trough concentrations. Voriconazole concentrations of <1.7 mg/liter were associated with a significantly greater incidence of treatment failure (19/74 patients [26%]) than concentrations of ≥1.7 mg/liter (6/89 patients [7%]) (P < 0.01). Neurotoxic adverse events (visual and auditory hallucinations) occurred more frequently at voriconazole concentrations of >5 mg/liter (10/31 patients [32%]) than at concentrations of ≤5 mg/liter (2/170 patients [1.2%]) (P < 0.01). Multiple regression analysis of voriconazole concentration identified associations between increasing patient weight, oral administration of voriconazole, and coadministration of phenytoin or rifampin and significantly reduced concentrations, and associations between increasing patient age and coadministration of proton pump inhibitors and increased concentrations. Coadministration of glucocorticoids was found to significantly reduce voriconazole concentrations, inferring a previously unreported drug interaction between glucocorticoids and voriconazole.

Mallory-Weiss syndrome: clinical and endoscopic characteristics

BACKGROUND

Mallory-Weiss syndrome is defined by upper gastrointestinal bleeding from vomiting-induced mucosal lacerations at the esophago-gastric junction. This study was purposed to investigate the incidence, location, clinical manifestation, diagnosis and effectiveness of treatment (including endoscopic treatment and conservative medical treatment) of Mallory-Weiss syndrome in China.

METHODS

All patients who received emergency upper gastrointestinal endoscopy due to Mallory-Weiss syndrome from September 2007 to August 2011 at gastrointestinal endoscopy center of Renmin Hospital of Wuhan University were included in this study. The clinical presentation, medical history, location and characteristics of Mallory-Weiss syndrome methods and effectiveness of therapy of patients with Mallory-Weiss syndrome were retrospectively analyzed by chart reviews. Long-term follow-up data were collected at outpatient clinics or telephone interviews.

RESULTS

Sixteen patients were diagnosed with Mallory-Weiss syndrome, which account for 3.08% of 519 patients with acute non-variceal upper gastrointestinal bleeding. Common comorbidities were found in one patient with hepatic cirrhosis. Conservative medical treatment, local injection, hemoclipping, or multipolar electrocoagulation produced primary hemostasis in 87.5% (14/16) of patients.

CONCLUSION

Mallory-Weiss syndrome is uncommon in China in comparison with reported experience in the west when the same group of patients is selected. Different approaches to treatment are to be recommended depending on whether or not active hemorrhage is present.

Pantoprazole for the treatment of peptic ulcer bleeding and prevention of rebleeding

Adding proton pump inhibitors (PPIs) to endoscopic therapy has become the mainstay of treatment for peptic ulcer bleeding, with current consensus guidelines recommending high-dose intravenous (IV) PPI therapy (IV bolus followed by continuous therapy). However, whether or not high-dose PPI therapy is more effective than low-dose PPI therapy is still debated. Furthermore, maintaining pH ≥ 4 appears to prevent mucosal bleeding in patients with acute stress ulcers; thus, stress ulcer prophylaxis with acid-suppressing therapy has been increasingly recommended in intensive care units (ICUs). This review evaluates the evidence for the efficacy of IV pantoprazole, a PPI, in preventing ulcer rebleeding after endoscopic hemostasis, and in controlling gastric pH and protecting against upper gastrointestinal (GI) bleeding in high-risk ICU patients. The review concludes that IV pantoprazole provides an effective option in the treatment of upper GI bleeding, the prevention of rebleeding, and for the prophylaxis of acute bleeding stress ulcers.

Comparison of the efficacy and safety of pantoprazole magnesium and pantoprazole sodium in the treatment of gastro-oesophageal reflux disease: a randomized, double-blind, controlled, multicentre trial

BACKGROUND

Proton pump inhibitors (PPIs) are well established as first-line agents for the treatment of moderate-to-severe gastro-oesophageal reflux disease (GORD). Although all PPIs heal oesophageal lesions and provide symptomatic relief, breakthrough symptoms may occur as acidity levels rebound. Pantoprazole magnesium (pantoprazole-Mg) has a longer elimination half-life than pantoprazole sodium (pantoprazole-Na), resulting in prolonged drug exposure.

OBJECTIVE

This study compares the clinical efficacy and safety of once-daily pantoprazole-Mg 40 mg with that of once-daily pantoprazole-Na 40 mg in the management of GORD.

METHODS

This was a randomized, double-blind, controlled, multicentre study of non-inferiority design in outpatients with GORD. The study was conducted in 53 centres in Germany from 12 May 2003 to 18 September 2003. Male or female outpatients (aged ≥18 years) with endoscopically confirmed GORD stage I-III (according to the Savary-Miller classification modified by Siewert) were enrolled. Using a computer-generated randomization list, patients were randomized to treatment with pantoprazole-Mg 40 mg plus placebo or pantoprazole-Na 40 mg plus placebo, both given once daily for 4 or 8 weeks depending on healing of oesophagitis. The primary objective was endoscopic healing at 8 weeks.

RESULTS

The intent-to-treat (ITT) group consisted of 636 patients (322 receiving pantoprazole-Mg and 314 receiving pantoprazole-Na). Endoscopically confirmed healing of reflux oesophagitis after 8 weeks occurred in 87.3% (95% CI 83.1, 90.7) of patients receiving pantoprazole-Mg and 85.0% (95% CI 80.6, 88.8) of patients receiving pantoprazole-Na (ITT population). The lower bound of the 95% CI for the between-group treatment difference was -1.3, which was within the predefined margin of non-inferiority of -10% to 0%. Healing rates after 4 weeks were superior in the pantoprazole-Mg group (72.7% [95% CI 67.5, 77.5]) compared with the pantoprazole-Na group (66.2% [95% CI 60.7, 71.5]), and the one-sided (lower bound) of the 95% CI for the difference between healing rates for the two treatments was within the predefined non-inferiority margin of -10% to 0%. Both treatments had a similar effect on GORD healing in subgroups of patients based on baseline oesophagitis grade and Helicobacter pylori status. Pantoprazole-Mg had similar efficacy to pantoprazole-Na in relieving a broad range of GORD-related symptoms across the course of the study, although symptomatic relief at 4 weeks was numerically higher in the pantoprazole-Mg group than in the pantoprazole-Na group (statistical analyses were not performed). Both treatments were well tolerated; most adverse events were of mild or moderate severity and unrelated to the study medication, and there were no unexpected safety concerns.

CONCLUSION

Pantoprazole-Mg is clinically as effective and well tolerated as pantoprazole-Na in the treatment of GORD stages I-III, demonstrating non-inferiority for oesophageal healing at 8 weeks and superior healing rates at 4 weeks associated with high levels of symptomatic relief.

Clinical usefulness of limited sampling strategies for estimating AUC of proton pump inhibitors

Cytochrome P450 (CYP) 2C19 (CYP2C19) genotype is regarded as a useful tool to predict area under the blood concentration-time curve (AUC) of proton pump inhibitors (PPIs). In our results, however, CYP2C19 genotypes had no influence on AUC of all PPIs during fluvoxamine treatment. These findings suggest that CYP2C19 genotyping is not always a good indicator for estimating AUC of PPIs. Limited sampling strategies (LSS) were developed to estimate AUC simply and accurately. It is important to minimize the number of blood samples because of patient's acceptance. This article reviewed the usefulness of LSS for estimating AUC of three PPIs (omeprazole: OPZ, lansoprazole: LPZ and rabeprazole: RPZ). The best prediction formulas in each PPI were AUC(OPZ)=9.24 x C(6h)+2638.03, AUC(LPZ)=12.32 x C(6h)+3276.09 and AUC(RPZ)=1.39 x C(3h)+7.17 x C(6h)+344.14, respectively. In order to optimize the sampling strategy of LPZ, we tried to establish LSS for LPZ using a time point within 3 hours through the property of pharmacokinetics of its enantiomers. The best prediction formula using the fewest sampling points (one point) was AUC(racemic LPZ)=6.5 x C(3h) of (R)-LPZ+13.7 x C(3h) of (S)-LPZ-9917.3 x G1-14387.2×G2+7103.6 (G1: homozygous extensive metabolizer is 1 and the other genotypes are 0; G2: heterozygous extensive metabolizer is 1 and the other genotypes are 0). Those strategies, plasma concentration monitoring at one or two time-points, might be more suitable for AUC estimation than reference to CYP2C19 genotypes, particularly in the case of coadministration of CYP mediators.

The role of proton pump inhibitors on early mycophenolic acid exposure in kidney transplantation: evidence from the CLEAR study

INTRODUCTION

Proton pump inhibitors (PPIs) are often prescribed posttransplantation to prevent gastrointestinal complications. A series of recent studies have reported a relationship between PPI comedication and decreased mycophenolic acid (MPA) exposure. The objective of this subanalysis of the CLEAR data set was to determine the impact of PPI therapy on full MPA area under the curve exposures at Day 5 post kidney transplant.

MATERIAL AND METHODS

Patients were randomized to receive either intensified dosing of mycophenolate mofetil (1.5 g twice daily on Days 1-5, then 1.0 g twice daily, n = 68) or standard dosing (1.0 g twice daily, n = 67). All recipients received tacrolimus and prednisone.

RESULTS

In the modified intention-to-treat population, 57.9% of patients (73 of 126) received PPI therapy. The most frequently administered therapies were pantoprazole and omeprazole. There was no significant difference in mean MPA area under the curve at Day 5 for patients receiving PPI therapy as compared with those not receiving PPI therapy (51.3 versus 55.8 mg.h/L, P = 0.265). However, the MPA concentration-time curve analysis demonstrated a significant decrease in MPA concentrations at 2 hours and 12 hours postdose in patients receiving PPI therapy (P = 0.0009 and P = 0.034). No significant differences were identified in the 3-g arm specifically. In the multivariate model, only serum creatinine and albumin significantly predicted MPA area under the curve less than 30 mg.h/L at Day 5.

DISCUSSION AND CONCLUSION

PPI therapy in combination with mycophenolate mofetil does not appear to have a significant impact on full MPA exposure. Because MPA pharmacokinetics were not significantly impacted when a 3-g, 5-day loading dose of mycophenolate mofetil was used in combination with PPI therapy, this strategy may be required for adequate MPA exposure whether or not a patient receives PPI comedication.

Randomized double-blind placebo-controlled crossover study to determine the effects of esomeprazole on inhibition of platelet function by clopidogrel

BACKGROUND

Pharmacokinetic studies suggest that clopidogrel and esomeprazole are metabolized by similar hepatic enzymes; however, previous studies have not identified a biochemical interaction.

OBJECTIVES

To determine whether addition of esomeprazole to patients receiving aspirin and clopidogrel reduces the antiplatelet effects of clopidogrel.

PATIENT/METHODS

Patients with a history of an acute coronary syndrome who had previously received clopidogrel were recruited. Subjects were commenced on clopidogrel and randomized to one of two treatment arms (esomeprazole or placebo) for 6 weeks. Following a 2-week washout period for study medications, patients were crossed over onto the alternative treatment arm for a further 6 weeks. Platelet function tests were undertaken at baseline, following the first treatment period, after washout and following the second treatment period.

RESULTS

Thirty-one patients were enrolled. Significant attenuation of clopidogrel's antiplatelet effects was seen with co-administration of esomeprazole compared with placebo. Vasodilator stimulated phosphoprotein (VASP), platelet aggregometry (area under the curve (AUC)) and VerifyNow results were 54.7% ± 2.8 platelet reactivity index (PRI), 66.3 ± 2.6 AUC units and 213.1 ± 14.1 platelet reactivity units (PRU) with esomeprazole vs. 47% ± 2.7 PRI, 59.7 ± 3.7 AUC units and 181.4 ± 14.6 PRU with placebo (P < 0.01 esomeprazole vs. placebo for all measures). There was no significant difference in platelet aggregometry (maximal aggregation) between the esomeprazole group (68.9% ± 2.7 units) and placebo-treated group (64.5% ± 4.1 units; P > 0.05).

CONCLUSION

Esomeprazole when co-administered with aspirin and clopidogrel results in a significant attenuation of clopidogrel's antiplatelet effects.