N.G. Hunfeld

Effect of CYP2C19*2 and *17 mutations on pharmacodynamics and kinetics of proton pump inhibitors in Caucasians

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT The influence of CYP2C19 on the kinetics and dynamics of omeprazole, lansoprazole and rabeprazole has been studied in Japanese subjects. * It has been suggested that subjects with *1/*1 genotype might need stronger acid suppression than *1/*2 and *2/*2 subjects. This suggestion comes from data in Japanese subjects and has not been confirmed in Caucasians. * Furthermore, a novel CYP2C19 mutation, *17, which mainly occurs in Caucasians has been discovered. This mutation has been associated with clinical failure, but its relevance for therapy with PPIs has not been studied yet. WHAT THIS STUDY ADDS In this study, the influence of CYP2C19 on both the pharmacokinetics and dynamics in Caucasian subjects after single and repeated dosing has been investigated. * This is the first study showing that Caucasian subjects with *1/*1 and *1/*17 mutations need stronger acid-inhibition. In this study three proton pump inhibitors (omeprazole, lansoprazole and pantoprazole, in different doses) were studied of which pantoprazole had not been studied before in this setting, not even in Japanese. AIMS To investigate the impact of CYP2C19 mutations *2-*6 and *17 on acid-inhibition and pharmacokinetics of lansoprazole (L15), omeprazole (O10, O20) and pantoprazole (P40) in Caucasians. METHODS CYP2C19 genotyping for *2-*6 and *17 mutations was assessed in subjects who were H. pylori negative in two randomized crossover trials. The influence of CYP2C19 mutations on single and repeated administration of L15 and O10 (study A) and O20 and P40 (study B) was investigated. Pharmacokinetics and the cumulative percentage of time with intragastric pH above 4 (% > pH 4) were assessed on day 1 and 6. RESULTS For study A CYP2C19 genotyping found five *1/*1, four *1/*2, one *1/*17 and one *2/*17. For study B the results were six *1/*1, two *1/*2, six *1/*17, one *2/*2 and one *2/*17. For all PPIs AUC was highest in *2/*2 and lowest in *1/*17. On day 1, all PPIs significantly increased percentage >pH 4 compared with baseline. *1/*1 genotype showed no significant acid-inhibition after L15, O10 and O20. *1/*17 genotype showed no significant acid-inhibition after O20 and P40. *1/*2 genotype showed significant acid-inhibition after L15 and O10. On day 6, all four PPIs showed significantly increased acid-inhibition. *1/*1 and *1/*17 showed a significantly increased percentage > pH 4 after treatment with O20 and P40. However, in *1/*1 subjects percentage > pH 4 was not significantly increased after L15 and O10. *1/*2 genotype showed a significant acid-inhibitory effect after repeated dosing with L15 and O10. CONCLUSIONS Caucasian subjects with *1/*1 and *1/*17 genotype need stronger acid-suppression therapy, especially during the first days of treatment or with on-demand therapy.

A comparison of the acid-inhibitory effects of esomeprazole and rabeprazole in relation to pharmacokinetics and CYP2C19 polymorphism

Esomeprazole and rabeprazole are metabolised in the liver by means of the CYP2C19 enzyme, which has several functional genetic polymorphisms. Among Caucasians, 70% of the population has a fast metaboliser phenotype, 25–30% an intermediate and 2–5% a slow metaboliser phenotype. It is unknown whether different PPIs are affected to the same extent by these phenotypic differences.

Altered Micafungin Pharmacokinetics in Intensive Care Unit Patients

ABSTRACT Micafungin is considered an important agent for the treatment of invasive fungal infections in the intensive care unit (ICU). Little is known on the pharmacokinetics of micafungin. We investigated micafungin pharmacokinetics (PK) in ICU patients and set out to explore the parameters that influence micafungin plasma concentrations. ICU patients receiving 100 mg of intravenous micafungin once daily for suspected or proven fungal infection or as prophylaxis were eligible. Daily trough concentrations and PK curves (days 3 and 7) were collected. Pharmacokinetic analysis was performed using a standard two-stage approach. Twenty patients from the ICUs of four hospitals were evaluated. On day 3 (n = 20), the median (interquartile range [IQR]) area under the concentration-time curve from 0 to 24 h (AUC0–24) was 78.6 (65.3 to 94.1) mg · h/liter, the maximum concentration of drug in serum (Cmax) was 7.2 (5.4 to 9.2) mg/liter, the concentration 24 h after dosing (C24) was 1.55 (1.4 to 3.1) mg/liter, the volume of distribution (V) was 25.6 (21.3 to 29.1) liters, the clearance (CL) was 1.3 (1.1 to 1.5) liters/h, and the elimination half-life (t1/2) was 13.7 (12.2 to 15.5) h. The pharmacokinetic parameters on day 7 (n = 12) were not significantly different from those on day 3. Daily trough concentrations (day 3 to the end of therapy) showed moderate interindividual (57.9%) and limited intraindividual variability (12.9%). No covariates of the influence on micafungin exposure were identified. Micafungin was considered safe and well tolerated. We performed the first PK study with very intensive sampling on multiple occasions in ICU patients, which aided in resolving micafungin PK. Strikingly, micafungin exposure in our cohort of ICU patients was lower than that in healthy volunteers but not significantly different from that of other reference populations. The clinical consequence of these findings must be investigated in a pharmacokinetic-pharmacodynamic (PK-PD) study incorporating outcome in a larger cohort. (This study is registered at ClinicalTrials.gov under registration no. NCT01783379.)

Switching to different generic medicines: a checklist for safety issues

Competition between commercially available generics results in lower prices and reduction of healthcare costs. However, the introduction of a new generic product may result in problems with the application in clinical practice. We composed a checklist to survey the differences between products. With this checklist we aim to detect properties of the alternative generic drug that might be problematic in clinical use. Timely prediction of the potential problems supports careful selection and introduction of the appropriate generic drug in the clinic. In this article, we discuss the different items in our checklist and mention some of the problems we have encountered in the last few years. We believe that by using this checklist, hospital pharmacists are better able to make the most appropriate choice of a generic drug for the local requirements of a hospital.

Evidence-Based Recommendations to Improve the Safe Use of Drugs in Patients with Liver Cirrhosis

IntroductionThe presence of liver cirrhosis can have a major impact on pharmacodynamics and pharmacokinetics, but guidance for prescribing is lacking.ObjectiveThe aim of this study is to provide an overview of evidence-based recommendations developed for the safe use of drugs in liver cirrhosis.MethodsRecommendations were based on a systematic literature search combined with expert opinion from a panel of 10 experts. The safety of each drug was classified as safe, no additional risks known, additional risks known, unsafe, unknown or the safety class was dependent on the severity of liver cirrhosis (Child–Pugh classification). If applicable, drug-specific dosing advice was provided. All recommendations were implemented in clinical decision support systems and on a website.ResultsWe formulated 218 recommendations for a total of 209 drugs. For nine drugs, two recommendations were formulated for different administration routes or indications. Drugs were classified as ‘safe’ in 29 recommendations (13.3%), ‘no additional risks known’ in 60 (27.5%), ‘additional risks known’ in 3 (1.4%), and ‘unsafe’ in 30 (13.8%). In 57 (26.1%) of the recommendations, safety depended on the severity of liver cirrhosis and was ‘unknown’ in 39 (17.9%) recommendations. Large alterations in pharmacodynamics were the main reason for classifying a drug as ‘unsafe’. For 67 drugs (31%), a dose adjustment was needed.ConclusionsOver 200 recommendations were developed for the safe use of drugs in patients with liver cirrhosis. Implementing these recommendations into clinical practice can possibly enhance medication safety in this vulnerable patient group.

Tyrosine Kinase Inhibitors and Proton Pump Inhibitors: An Evaluation of Treatment Options

Tyrosine kinase inhibitors (TKIs) have rapidly become an established factor in oncology, and have been shown to be effective in a wide variety of solid and hematologic malignancies. Use of the oral administration route of TKIs offers flexibility and is convenient for the patient; however, despite these advantages, the oral route of administration also causes a highly relevant new problem. Acid-inhibitory drugs, such as proton pump inhibitors (PPIs), increase the intragastric pH, which may subsequently decrease TKI solubility, bioavailability, and treatment efficacy. Clear and practical advice on how to manage PPI use during TKI therapy is currently not available in the literature. Since PPIs are extensively used during TKI therapy, prescribers are presented with a big dilemma as to whether or not to continue the combined treatment, resulting in patients possibly being deprived of optimal therapy. When all pharmacological characteristics and data of either TKIs and PPIs are considered, practical and safe advice on how to manage this drug combination can be given.

Evaluating the safety and dosing of drugs in patients with liver cirrhosis by literature review and expert opinion

Introduction Liver cirrhosis can have a major impact on drug pharmacokinetics and pharmacodynamics. Patients with cirrhosis often suffer from potentially preventable adverse drug reactions. Guidelines on safe prescribing for these patients are lacking. The aim of this study is to develop a systematic method for evaluating the safety and optimal dosage of drugs in patients with liver cirrhosis. Methods and analysis For each drug, a six-step evaluation process will be followed. (1) Available evidence on the pharmacokinetics and safety of a drug in patients with liver cirrhosis will be collected from the Summary of Product Characteristics (SmPC) and a systematic literature review will be performed. (2) Data regarding two outcomes, namely pharmacokinetics and safety, will be extracted and presented in a standardised assessment report. (3) A safety classification and dosage suggestion will be proposed for each drug. (4) An expert panel will discuss the validity and clinical relevance of this suggested advice. (5) Advices will be implemented in all relevant Clinical Decision Support Systems in the Netherlands and published on a website for patients and healthcare professionals. (6) The continuity of the advices will be guaranteed by a yearly check of new literature and comments on the advices. This protocol will be applied in the evaluation of a selection of drugs: (A) drugs used to treat (complications of) liver cirrhosis, and (B) drugs frequently prescribed to the general population. Ethics and dissemination Since this study does not directly involve human participants, it does not require ethical clearance. Besides implementation on a website and in clinical decision support systems, we aim to publish the generated advices of one or two drug classes in a peer-reviewed journal and at conference meetings.

Safe use of proton pump inhibitors in patients with cirrhosis

Proton pump inhibitors (PPIs) belong to the most frequently used drugs, also in patients with cirrhosis. PPIs are extensively metabolized by the liver, but practice guidance on prescribing in cirrhosis is lacking. We aim to develop practical guidance on the safe use of PPIs in patients with cirrhosis.

The effect of the TIM program (Transfer ICU Medication reconciliation) on medication transfer errors in two Dutch intensive care units: design of a prospective 8-month observational study with a before and after period

BackgroundThe transfer of patients to and from the Intensive Care Unit (ICU) is prone to medication errors. The aim of the present study is to determine whether the number of medication errors at ICU admission and discharge and the associated potential harm and costs are reduced by using the Transfer ICU and Medication reconciliation (TIM) program.MethodsThis prospective 8-month observational study with a pre- and post-design will assess the effects of the TIM program compared with usual care in two Dutch hospitals. Patients will be included if they are using at least one drug before hospital admission and will stay in the ICU for at least 24 h. They are excluded if they are transferred to another hospital, admitted and discharged in the same weekend or unable to communicate in Dutch or English.In the TIM program, a clinical pharmacist reconciles patient’s medication history within 24 h after ICU admission, resulting in a “best possible” medication history and presents it to the ICU doctor. At ICU discharge the clinical pharmacist reconciles the prescribed ICU medication and the medication history with the ICU doctor, resulting in an ICU discharge medication list with medication prescription recommendations for the general ward doctor. Primary outcome measures are the proportions of patients with one or more medication transfer errors 24 h after ICU admission and 24 h after ICU discharge. Secondary outcome measures are the proportion of patients with potential adverse drug events, the severity of potential adverse drug events and the associated costs.For the primary outcome relative risks and 95% confidence intervals will be calculated.DiscussionStrengths of this study are the tailor-made design of the TIM program and two participating hospitals. This study also has some limitations: A potential selection bias since this program is not performed during the weekends, collecting of potential rather than actual adverse drug events and finally a relatively short study period.Nevertheless, the findings of this study will provide valuable information on a crucial safety intervention in the ICU.Trial registrationDutch trial register: NTR4159, 5 September 2013

T1085 Effect of CYP2C19 Genotype On Control of Gastric Acidity with Rabeprazole and Esomeprazole After Single and Repeated Oral Administration

Introduction: Esomeprazole (eso) and rabeprazole (rabe) are metabolized in the liver. Genetic polymorphism of the cytochrome P-450 enzyme CYP2C19 determines fast (homozygous extensive metabolizers, wt/wt), intermediate (heterozygous extensive metabolizers, wt/∗2 or wt/∗3) and slow (poor metabolizers, ∗2/∗2, ∗3/∗3 or ∗2/∗3) or rapid (wt/∗17 or ∗17/∗17) metabolism of proton pump inhibitors (PPIs). In the Caucasian population 60% has the wt/ wt genotype, 30-40% is wt/∗2 and 2-5% ∗2/∗2. Aim: To investigate the impact of CYP2C19 genotype on control of gastric acidity (median pH and % of time pH