Pharmacogenetics of antimalarial drugs: effect on metabolism and transport.

The prevention and management of malaria is primarily based on the use of drugs. Clinical trials have however revealed that between individuals there is large variability in the pharmacokinetic profiles of many antimalarial drugs. The resulting variations in concentrations of the drug within plasma might lead to either suboptimum effectiveness or drug toxicity in some patients. The evidence is increasing that polymorphically expressed drug-metabolising enzymes, predominantly various cytochrome P450 isozymes but also drug transporters, might contribute to the variability in drug response (incomplete cure, relapse, or resistance) or toxicity experienced with antimalarial drugs. For example, there is a clear association between concentrations of proguanil within plasma and certain genetic polymorphisms of CYP2C19, and genetically established levels of CYP2C8 might have important clinical implications in the toxicity of amodiaquine. Variation in the expression of drug-metabolising enzymes and transport proteins affects the pharmacology of antimalarial drugs. Exploration of pharmacogenetics might help to optimise the use of antimalarial drugs.

Prediction of breast cancer by profiling of urinary RNA metabolites using Support Vector Machine-based feature selection.

BACKGROUND: Breast cancer belongs to the most frequent and severe cancer types in human. Since excretion of modified nucleosides from increased RNA metabolism has been proposed as a potential target in pathogenesis of breast cancer, the aim of the present study was to elucidate the predictability of breast cancer by means of urinary excreted nucleosides. METHODS: We analyzed urine samples from 85 breast cancer women and respective healthy controls to assess the metabolic profiles of nucleosides by a comprehensive bioinformatic approach. All included nucleosides/ribosylated metabolites were isolated by cis-diol specific affinity chromatography and measured with liquid chromatography ion trap mass spectrometry (LC-ITMS). A valid set of urinary metabolites was selected by exclusion of all candidates with poor linearity and/or reproducibility in the analytical setting. The bioinformatic tool of Oscillating Search Algorithm for Feature Selection (OSAF) was applied to iteratively improve features for training of Support Vector Machines (SVM) to better predict breast cancer. RESULTS: After identification of 51 nucleosides/ribosylated metabolites in the urine of breast cancer women and/or controls by LC- ITMS coupling, a valid set of 35 candidates was selected for subsequent computational analyses. OSAF resulted in 44 pairwise ratios of metabolite features by iterative optimization. Based on this approach ultimately estimates for sensitivity and specificity of 83.5% and 90.6% were obtained for best prediction of breast cancer. The classification performance was dominated by metabolite pairs with SAH which highlights its importance for RNA methylation in cancer pathogenesis. CONCLUSION: Extensive RNA-pathway analysis based on mass spectrometric analysis of metabolites and subsequent bioinformatic feature selection allowed for the identification of significant metabolic features related to breast cancer pathogenesis. The combination of mass spectrometric analysis and subsequent SVM-based feature selection represents a promising tool for the development of a non-invasive prediction system.

Epinephrine inhalers in emergency sets of patients with anaphylaxis.

Emergency sets are prescribed to allow patients with anaphylaxis to treat themselves before professional aid arrives. The need for epinephrine in this setting is well-accepted, but how it should be administered is still controversial. Epinephrine preparations can be administered orally, subcutaneously, intramuscularly or as aerosols. Primatene Mist is one epinephrine inhaler, which is approved for asthma treatment in the USA, and InfectoKrupp Inhal is another one approved to support the treatment of acute laryngo-tracheitis and of allergic reactions with a nebulizer. Both are possible components of the emergency set for patients with anaphylaxis. The following review article summarizes data currently available on the use of epinephrine preparations in first-aid treatment of anaphylaxis. Studies have shown that the plasma concentrations needed for hemodynamic stabilization cannot be reached with epinephrine inhalers. Since most cases of hypotension in anaphylaxis cannot be effectively treated with epinephrine inhalers, the prescriber should be aware of this before including them in an emergency pack.

Identification of urinary modified nucleosides and ribosylated metabolites in humans via combined ESI-FTICR MS and ESI-IT MS analysis.

The physiological response of the human body to several diseases can be reflected by the metabolite pattern in biological fluids. Cancer, like other diseases accompanied by metabolic disorders, causes characteristic effects on cell turnover rate, activity of modifying enzymes, and RNA/DNA modifications. This results in an altered excretion of modified nucleosides and biochemically related compounds. In the course of our metabolic profiling project, we screened 24-h urine of patients suffering from lung, rectal, or head and neck cancer for previously unknown ribosylated metabolites. Therefore, we developed a sample preparation procedure based on boronate affinity chromatography followed by additional prepurification with preparative TLC. The isolated metabolites were analyzed by ion trap mass spectrometry (IT MS) and Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS). IT MS was applied for LC-auto MS(3) screening runs and MS(n(n=4-6)) syringe pump infusion experiments, yielding characteristic fragmentation patterns. FTICR MS measurements enabled the calculation of corresponding molecular formulae based on accurate mass determination (mass accuracy: 1-5 ppm for external and sub-ppm values for internal calibration). We were able to identify 22 metabolites deriving from cellular RNA metabolism and related metabolic pathways like histidine metabolism, purine biosynthesis, methionine/polyamine cycle, and nicotinate/nicotinamide metabolism. The compounds 1-ribosyl-3-hydroxypyridinium, 1-ribosyl-pyridinium, and 3-ribosyl-1-methyl-l-histidinium as well as a series of ribosylated histamines, conjugated to carboxylic acids at the N(omega)-position were found as novel urinary constituents. The occurrence of the modified nucleosides 2-methylthio-N(6)-(cis-hydroxyisopentenyl)-adenosine, 5-methoxycarbonylmethyl-2-thiouridine, N(6)-methyl-N(6)-threonylcarbamoyladenosine, and 2-methylthio-N(6)-threonylcarbamoyladenosine in human urine is verified for the first time.

Effect of high-dose metronidazole on pharmacokinetics of oral budesonide and vice versa: a double drug interaction study.

Recent case reports suggest that addition of high-dose metronidazole might be associated with elevated plasma concentrations of substrates of cytochrome P450 (CYP) 3A. Because patients with fistulizing Crohn's disease benefit by using high doses of metronidazole for prolonged periods, this study's primary aim was to evaluate the effect of high-dose metronidazole on the pharmacokinetics of oral budesonide, a sensitive substrate of CYP3A commonly prescribed in acute inflammatory bowel disease. Twelve healthy adults received 1.5 g metronidazole per day over 1 week. The CYP3A-dependent metabolic profile of an oral dose of budesonide (3 mg) and that of endogenous cortisol were compared intraindividually before and after administration of metronidazole. There was neither a significant effect of high-dose metronidazole on the area under the plasma concentration-time curve (AUC) of budesonide (90% confidence interval, 79%-115%) nor on the AUC ratios of 6beta-hydroxybudesonide/budesonide and 16alpha-hydroxyprednisolone/budesonide. In parallel, metronidazole did not significantly alter formation of 6beta-hydroxycortisol. Vice versa, budesonide did not affect the AUC of metronidazole (90% confidence interval, 91%-100%). The authors conclude that in contrast to concomitant intake of other imidazoles such as ketoconazole, concomitant intake of metronidazole may not lead to serious safety concerns due to elevated systemic concentrations of the glucocorticoid budesonide.

Dose-proportional intraindividual single- and repeated-dose pharmacokinetics of roflumilast, an oral, once-daily phosphodiesterase 4 inhibitor.

The dose-proportional, intraindividual, single- and repeated-dose pharmacokinetics of roflumilast, an oral, once-daily phosphodiesterase 4 inhibitor under investigation for chronic obstructive pulmonary disease and asthma, was investigated in healthy subjects. In an open, randomized, 2-period, 2-sequence crossover study, 15 subjects received immediate-release tablets of roflumilast 250 or 500 microg as single (day 1) and as repeated, once-daily doses for 8 days (days 5-12). Dose-adjusted point estimates and 90% confidence intervals of test (500 microg)/reference (250 microg) ratios for AUC and Cmax of roflumilast and its pharmacologically active N-oxide metabolite after single and repeated dosing were all within the standard equivalence acceptance range (0.80, 1.25) indicating dose proportionality. The pharmacokinetic properties of both roflumilast dosage forms provide clinically relevant evidence of predictable, intraindividual total (AUC) and maximum (Cmax) exposure of roflumilast and roflumilast N-oxide. Repeated oral dosing with roflumilast 250 and 500 microg once daily was well tolerated.

Impact of CYP2D6 genotype on adverse effects during treatment with metoprolol: a prospective clinical study.

OBJECTIVE: Our objective was to study the impact of the cytochrome P450 (CYP) 2D6 polymorphism on the tolerability of metoprolol in a real-life primary care setting. The adverse effects studied comprised effects related to the central nervous system, cardiovascular effects, and sexual dysfunction. METHODS: Patients in whom treatment with metoprolol was considered were enrolled into this prospective, 6-week multicenter study. The dosage of metoprolol was determined on an individual basis and could be freely adjusted on clinical grounds. The indication for treatment was hypertension in about 90% of cases. Systolic and diastolic blood pressure, resting heart rate, and plasma metoprolol and alpha-hydroxymetoprolol concentrations were measured. CYP2D6 genotyping covered alleles *3 to *10 and *41 and the duplications. Possible adverse effects of metoprolol were systematically assessed over a 6-week period by means of standardized rating scales and questionnaires. RESULTS: The final study population comprised 121 evaluable patients (all white patients); among them, there were 5 ultrarapid metabolizers (UMs) (4.1%), 91 extensive metabolizers (EMs) (75%), 21 intermediate metabolizers (IMs) (17%), and 4 poor metabolizers (PMs) (3.3%). Plasma metoprolol concentrations normalized for the daily dose and metoprolol/alpha-hydroxymetoprolol ratios at steady state were markedly influenced by CYP2D6 genotype and displayed a gene-dose effect. The median of the dose-normalized metoprolol concentration was 0.0088 ng/mL, 0.047 ng/mL, 0.34 ng/mL, and 1.34 ng/mL among UMs, EMs, IMs, and PMs, respectively (P<.0001). There was no significant association between CYP2D6 genotype-derived phenotype (EMs and UMs combined versus PMs and IMs combined) and adverse effects during treatment with metoprolol. There was a tendency toward a more frequent occurrence of cold extremities in the PM plus IM group as compared with the EM plus UM group (16.0% versus 4.2%, P=.056; relative risk, 3.8 [95% confidence interval, 1.03--14.3]). CONCLUSIONS: CYP2D6 genotype-derived phenotype was not significantly associated with a propensity for adverse effects to develop during treatment with metoprolol. However, the results concerning tolerability of metoprolol in PMs were inconclusive because of the small number of PMs enrolled.

Adaptation of a high-performance liquid chromatographic method for quantitative determination of homocysteine in urine.

A modification of the Bio-Rad total homocysteine HPLC-test is presented in order to enable not only plasma homocysteine measurements but also the quantification of homocysteine in urine samples using the same principle of measurement. Coelution of the internal standard provided in the test kit with an endogenous compound in urine demands for an alternative analytical procedure. Therefore, we introduced 3-mercaptopropionic acid as a substitute for the internal standard. The analytical method validation was performed for the matrix of urine specimens. The applicability of this method was demonstrated in a clinical study with volunteers after homocysteine thiolactone hydrochloride loading.

Cyclooxygenase-2 expression in human colorectal cancer is unrelated to overall patient survival.

PURPOSE: Cyclooxygenase-2 (COX-2) expression in human colorectal cancer and adenoma tissue seems to be higher than in normal mucosa. However, data about the relation between COX-2 expression and patient survival are inconclusive as yet. Therefore, we studied COX-2 expression in surgery tissue and survival time in a cohort of 747 colorectal cancer patients. EXPERIMENTAL DESIGN: Surgical specimens of primary colorectal cancer from 747 individuals were immunostained for COX-2 and evaluated under a transmission light microscope. COX-2 expression was scored according to intensity and extent of staining, resulting in the COX-2 immunoreactivity score (IRS-COX2). All possible cutoff points for IRS-COX2 were analyzed for a relation between COX-2 expression and patient survival. RESULTS: Both univariable and multivariable analysis have shown that the COX-2 expression in human tumor epithelial cells was unrelated to overall patient survival and to disease-free survival, irrespectively of the cutoff point for IRS-COX2. The survival rates for 1, 3, 5, and 10 years were 81.0%, 66.8%, 60.2%, and 49.8% (median: 117.3 months; 95% confidence interval, 102.3-132.0), respectively. In the multivariable analysis, only node and metastasis were significantly related to overall patient survival. Similar results were obtained when stage IV and rectal cancer patients were excluded from the analysis. CONCLUSIONS: COX-2 expression in tumor epithelial cells does not seem to be related to survival of colorectal cancer patients. Besides COX-2, there are several targets, such as the peroxisome proliferator-activated receptors, that are involved in carcinogenesis and may be modulated by nonsteroidal anti-inflammatory drugs. Further studies are needed to determine their prognostic relevance.

Ginger-associated overanticoagulation by phenprocoumon.

OBJECTIVE: To report a case of ginger-phenprocoumon interaction resulting in an elevated international normalized ratio (INR) and epistaxis. CASE SUMMARY: A 76-year-old white European woman on long-term phenprocoumon therapy with an INR within the therapeutic range began using ginger products. Several weeks later, she developed an elevated INR up to 10 and epistaxis. The INR returned to the normal range after ginger was stopped and vitamin K1 was given. DISCUSSION: There have been a number of investigations resulting in conflicting opinions on the effect of ginger on hemostasis, specifically, platelet inhibition. Nevertheless, based on these investigations, recommendations have been issued to refrain from ingesting ginger and other herbals like garlic or ginkgo biloba in situations where bleeding may be critical. An objective causality assessment revealed that the adverse drug event as a result of the phenprocoumon and ginger interaction was probable. CONCLUSIONS: As of writing, this was the first case report that may support an interaction between an oral anticoagulant and ginger together with a brief review of the literature on ginger and hemostasis. As this interaction was observed only by chance, this case highlights the importance of self-control of anticoagulation with coumarins particularly for the detection of unknown interactions.

[Rationale and methods of the UNAMET study (dose- and CYP2D6-genotype-dependent adverse drug reactions of metoprolol)--a contribution to quality improvement in pharmacotherapy]. / Rationale und Methodik der UNAMET-studie (Unerwünschte Arzneimittelwirkungen von Metoprolol in Abhängigkeit von Dosis und CYP2D6-Genotyp)--ein Beitrag zur Qualitäts- verbesserung in der Pharmakotherapie.

Metoprolol has not yet been systematically studied in terms of quality of life and incidence of adverse drug reactions (ADRs). Metoprolol is metabolized by polymorphic CYP2D6, therefore poor CYP2D6 metabolizers may be at higher risk of ADRs. Therefore, it is to be proven whether genotyping is useful to guide initial dose selection. In the ongoing UNAMET study, nonrandomized out-patients start treatment with metoprolol for various disorders. With the use of standard questionnaires, the patients are prospectively evaluated for common ADRs (headache, dizziness, tiredness, sleep disturbances, dyspnea, cold extremities, sexual dysfunction) and quality of life. The questionnaires are filled out before and until 6 weeks after initiating therapy; blood pressure and heart rate are also measured. The acquired data are then related to the patients' metoprolol dose and plasma concentrations, as well as to their metabolic ratio of metoprolol/alpha-OH-metoprolol and CYP2D6 genotype.

[Quality of antithrombotic therapy in patients with chronic atrial fibrillation: the AFib Trial]. / Qualität der antithrombotischen Therapie bei chronischem Vorhofflimmern: AFib-Studie.

BACKGROUND: Large randomised studies have definitely shown that oral anticoagulation effectively reduces thromboembolic complications, e.g. stroke, in patients with chronic non-valvular atrial fibrillation (AFib). However, less than 50% of the eligible AFib patients receive anticoagulation, although their risk of thromboembolic disease is increased 5-7 fold as compared to individuals who have a regular sinus rhythm. This is the reason why undertreatment needs to be evaluated and addressed. In Germany, data on the antithrombotic therapy of these patients are sparse, national guidelines are lacking. AIM OF THE STUDY: This prospective cohort study is the first one to evaluate the quality of antithrombotic prevention in two groups of AFib outpatients in two different, socio-demographically comparable regions of Germany (Südbaden and Südwürttemberg) over a period of several years. Quality of care is defined as the percentage of AFib patients in a certain region treated according to international guidelines. If the percentage in both cohorts does not exceed 80%, guidelines are to be developed and implemented in Südwürttemberg on consideration of the specific treatment conditions in this region; their applicability is to be evaluated later. METHODS: Office-based specialists of internal and general medicine are currently recruiting 200 AFib patients in each study region for documentation of their clinical data. Besides the quality of antithrombotic chemoprevention, relevant problems emerging in antithrombotic therapy in an ambulant setting will be identified. In the area of intervention (Südwürttemberg) experts and office-based physicians will exclusively develop evidence-based guidelines and disseminate them among doctors. Six months after the implementation of these guidelines in Südwürttemberg, their influence on prescribing patterns will be determined by comparing the proportion of anticoagulated AFib patients in Südwürttemberg to that of the control cohort (Südbaden). In addition, secondary outcomes of interest include deaths, days of hospitalisation, and incidence of stroke or bleeding episodes for different antithrombotic treatments.