Effects of the antifungal agents on oxidative drug metabolism: clinical relevance

A Simple HPLC-UV Method for Ivosidenib Determination in Human Plasma

Ivosidenib is used for the treatment of acute myeloid leukemia (AML) with isocitrate dehydrogenase 1 (IDH1) mutations. However, increased blood concentrations of ivosidenib are associated with a risk of a prolonged QT interval in patients with AML. Therapeutic drug monitoring in patients with AML with IDH1 mutation offers the potential to improve treatment efficacy while minimizing toxicity. In this study, we developed an efficient high-performance liquid chromatography-ultraviolet (HPLC-UV) method for the quantification of ivosidenib in plasma. Human plasma samples (50 μL) were processed by protein precipitation using acetonitrile, followed by chromatographic separation on a reversed-phase column with an isocratic mobile phase of 0.5% KH₂PO₄ (pH 4.5) and acetonitrile (45:55, v/v) at a flow rate of 1.0 mL/min, with ultraviolet detection at 245 nm. Calibration curves were linear over the range of 0.25-20 μg/mL with a coefficient of determination (r2) of 0.99999. Intra-day and inter-day precision were 1.20-8.04% and 0.69-4.20%, respectively. The assay accuracy was -2.00% to 1.93% and recovery was >91.2%. These findings support the effectiveness of the newly developed HPLC-UV method for the quantification of ivosidenib in human plasma. This simple and cost-effective method is expected to expand ivosidenib monitoring in laboratories lacking LC-MS/MS instruments.

Frequent premature ventricular contractions induced by fluconazole: A case report

Introduction

Fluconazole is commonly used to treat and prevent fungal infections caused by Candida and Cryptococcus species. Although there have been reports of fatal arrhythmias induced by fluconazole, such as torsades de pointes, there have been minimal reports of mild, non-fatal arrhythmias associated with it, which may have been overlooked in clinical practice. We encountered a case of frequent premature ventricular contractions induced by fluconazole during the treatment of HIV-related pulmonary cryptococcosis. Herein, we report a case of frequent premature ventricular contractions (PVCs) induced by fluconazole, along with a literature review.

Case presentation

A 47-year-old man diagnosed with human immunodeficiency virus-related pulmonary cryptococcosis experienced an irregular heartbeat during antifungal therapy with fluconazole at 400 mg once daily. A 12-lead electrocardiogram was conducted, which displayed frequent unifocal PVCs originating in the right ventricular outflow tract without QT prolongation. After reducing the dose of fluconazole to 200 mg once daily, the patient's symptoms slightly improved, and PVC frequency decreased on a 12-lead ECG; however, PVCs did not disappear. After discontinuing fluconazole, the symptoms improved, and a follow-up 12-lead electrocardiogram showed no PVCs.

Conclusions

We encountered the case of frequent PVCs induced by fluconazole during the treatment of human immunodeficiency virus-related pulmonary cryptococcosis. Furthermore, it was suggested that the PVC frequency was dose-dependent for fluconazole. Careful follow-up for new-onset arrhythmias and ECG evaluations are essential before and after fluconazole administration.

Vincristine Disposition and Neurotoxicity Are Unchanged in Humanized CYP3A5 Mice

Previous studies have suggested that the incidence of vincristine-induced peripheral neuropathy (VIPN) is potentially linked with cytochrome P450 (CYP)3A5, a polymorphic enzyme that metabolizes vincristine in vitro, and with concurrent use of azole antifungals such as ketoconazole. The assumed mechanism for these interactions is through modulation of CYP3A-mediated metabolism, leading to decreased vincristine clearance and increased susceptibility to VIPN. Given the controversy surrounding the contribution of these mechanisms, we directly tested these hypotheses in genetically engineered mouse models with a deficiency of the entire murine Cyp3a locus [Cyp3a(-/-) mice] and in humanized transgenic animals with hepatic expression of functional and nonfunctional human CYP3A5 variants. Compared with wild-type mice, the systemic exposure to vincristine was increased by only 1.15-fold (95% confidence interval, 0.84-1.58) in Cyp3a(-/-) mice, suggesting that the clearance of vincristine in mice is largely independent of hepatic Cyp3a function. In line with these observations, we found that Cyp3a deficiency or pretreatment with the CYP3A inhibitors ketoconazole or nilotinib did not influence the severity and time course of VIPN and that exposure to vincristine was not substantially altered in humanized CYP3A5*3 mice or humanized CYP3A5*1 mice compared with Cyp3a(-/-) mice. Our study suggests that the contribution of CYP3A5-mediated metabolism to vincristine elimination and the associated drug-drug interaction potential is limited and that plasma levels of vincristine are unlikely to be strongly predictive of VIPN. SIGNIFICANCE STATEMENT: The current study suggests that CYP3A5 genotype status does not substantially influence vincristine disposition and neurotoxicity in translationally relevant murine models. These findings raise concerns about the causality of previously reported relationships between variant CYP3A5 genotypes or concomitant azole use with the incidence of vincristine neurotoxicity.

Quantitation of Venetoclax in Human Plasma by High-Performance Liquid Chromatography with Ultraviolet Detection

A simple, highly sensitive and specific method based on high-performance liquid chromatography (HPLC) with ultraviolet detection was developed for the measurement of venetoclax concentrations in plasma samples. The chromatographic method employed a mobile phase of acetonitrile: 0.5% KH2PO4 (pH 3.5) (80/20, v/v) on a CAPCELL PAK C18 UG120 column at a flow rate of 0.5 mL/min. The quantitative method was validated based on standards described in "Bioanalytical Method Validation: Guidance for Industry" published by the US Food and Drug Administration. The separation of venetoclax and the internal standard R051012 was satisfactory, and the chromatograms were free of interfering peaks from the biological matrix. The intra- and inter-day coefficients of variation for venetoclax assays were <12.9%, whereas intra- and inter-day accuracies were within 13.6%. Only 100 μL of human plasma was required to detect a lower limit of quantification of 10 ng/mL for venetoclax. The recoveries of venetoclax extracted with an Oasis HLB cartridge were between 81 and 85%. The developed HPLC method was successfully applied to the determination of venetoclax concentrations in plasma of acute myeloid leukemia patients taking venetoclax. The degree of drug interactions between venetoclax and CYP3A4 inhibitors can be determined by this HPLC assay.

Pharmacokinetic boosting of olaparib: A randomised, cross-over study (PROACTIVE-study)

BACKGROUND

Pharmacokinetic (PK) boosting is the intentional use of a drug-drug interaction to enhance systemic drug exposure. PK boosting of olaparib, a CYP3A-substrate, has the potential to reduce PK variability and financial burden. The aim of this study was to investigate equivalence of a boosted, reduced dose of olaparib compared to the non-boosted standard dose.

METHODS

This cross-over, multicentre trial compared olaparib 300 mg twice daily (BID) with olaparib 100 mg BID boosted with the strong CYP3A-inhibitor cobicistat 150 mg BID. Patients were randomised to the standard therapy followed by the boosted therapy, or vice versa. After seven days of each therapy, dense PK sampling was performed for noncompartmental PK analysis. Equivalence was defined as a 90% Confidence Interval (CI) of the geometric mean ratio (GMR) of the boosted versus standard therapy area under the plasma concentration-time curve (AUC0-12 h) within no-effect boundaries. These boundaries were set at 0.57-1.25, based on previous pharmacokinetic studies with olaparib capsules and tablets.

RESULTS

Of 15 included patients, 12 were eligible for PK analysis. The GMR of the AUC0-12 h was 1.45 (90% CI 1.27-1.65). No grade ≥3 adverse events were reported during the study.

CONCLUSIONS

Boosting a 100 mg BID olaparib dose with cobicistat increases olaparib exposure 1.45-fold, compared to the standard dose of 300 mg BID. Equivalence of the boosted olaparib was thus not established. Boosting remains a promising strategy to reduce the olaparib dose as cobicistat increases olaparib exposure Adequate tolerability of the boosted therapy with higher exposure should be established.

Probiotics and their postbiotics for the control of opportunistic fungal pathogens: A review

During past twenty years the opportunistic fungal infections have been emerging, causing morbidity and mortality. The fungi belonging to Aspergillus, Mucor, Rhizopus, Candida, Fusarium, Penicillium, Dermatophytes and others cause severe opportunistic fungal infections. Among these Aspergillus and Candida spp cause majority of the diseases. The continuum of fungal infections will prolong to progress in the surroundings of the growing inhabitants of immunocompromised individuals. Presently many chemical-based drugs were used as prophylactic and therapeutic agents. Prolonged usage of antibiotics may lead to some severe effect on the human health. Also, one of the major threats is that the fungal pathogens are becoming the drug resistant. There are many physical, chemical, and mechanical methods to prevent the contamination or to control the disease. Owing to the limitations that are observed in such methods, biological methods are gaining more interest because of the use of natural products which have comparatively less side effects and environment friendly. In recent years, research on the possible use of natural products such as probiotics for clinical use is gaining importance. Probiotics, one of the well studied biological products, are safe upon consumption and are explored to treat various fungal infections. The antifungal potency of major groups of probiotic cultures such as Lactobacillus spp, Leuconostoc spp, Saccharomyces etc. and their metabolic byproducts which act as postbiotics like organic acids, short chain fatty acids, bacteriocin like metabolites, Hydrogen peroxide, cyclic dipeptides etc. to inhibit these opportunistic fungal pathogens have been discussed here.

Dosage Optimization of Digoxin in Older Patients with Heart Failure and Chronic Kidney Disease: A Population Pharmacokinetic Analysis

BACKGROUND

Renal function is an important index for digoxin dose adjustment, especially in patients with chronic kidney disease (CKD). Decreased glomerular filtration rate is common in older patients with cardiovascular disease.

OBJECTIVE

The aim of this study was to establish a digoxin population pharmacokinetic model in older patients with heart failure and CKD and to optimize the digoxin dose strategy.

METHODS

Older patients with heart failure and CKD aged > 60 years from January 2020 to January 2021 and who had an estimated glomerular filtration rate (eGFR) < 90 mL/min/1.73 m² or urine protein production were enrolled in this retrospective study. Population pharmacokinetic analysis and Monte Carlo simulations (n = 1000) were performed using NONMEN software. The precision and stability of the final model were analyzed by graphical and statistical methods.

RESULTS

Overall, 269 older patients with heart failure were enrolled. A total of 306 digoxin concentrations were collected, with a median value of 0.98 ng/mL (interquartile range [IQR] 0.62-1.61, range 0.04-4.24). The median age was 68 years (IQR 64-71, range 60-94) and eGFR was 53.6 mL/min/1.73 m² (IQR 38.1-65.2, range 11.4-89.8). A one-compartment model with first-order elimination was developed to describe the digoxin pharmacokinetics. Typical values for clearance and volume of distribution were 2.67 L/h and 36.9 L, respectively. Dosage simulations were stratified by eGFR and metoprolol. Doses of 62.5 and 125 μg were recommended for older patients with eGFR < 60 mL/min/1.73 m².

CONCLUSIONS

A population pharmacokinetic model of digoxin in older patients with heart failure and CKD was established in this study. A novel digoxin dosage strategy was recommended in this vulnerable population.

Drug-drug interactions involving CFTR modulators: a review of the evidence and clinical implications

INTRODUCTION

Cystic fibrosis (CF) is characterized by mucus accumulation impairing the lungs, gastrointestinal tract, and other organs. Cystic fibrosis transmembrane conductance regulator (CFTR) modulators (ivacaftor, tezacaftor, elexacaftor, and lumacaftor) significantly improve lung function and nutritional status; however, they are substrates, inhibitors, and/or inducers of certain CYP enzymes and transporters, raising the risk of drug-drug interactions (DDI) with common CF medications.

AREAS COVERED

A literature search was conducted for DDIs involving CFTR modulators by reviewing new drug applications, drug package inserts, clinical studies, and validated databases of substrates, inhibitors, and inducers. Clinically, CYP3A inducers and inhibitors significantly decrease and increase systemic concentrations of elexacaftor/tezacaftor/ivacaftor, respectively. Additionally, lumacaftor and ivacaftor alter concentrations of CYP3A and P-gp substrates. Potential DDIs without current clinical evidence include ivacaftor and elexacaftor's effect on CYP2C9 and OATP1B1/3 substrates, respectively, and OATP1B1/3 and P-gp inhibitors' effect on tezacaftor. A literature review was conducted using PubMed.

EXPERT OPINION

Dosing recommendations for CFTR modulators with DDIs are relatively comprehensive; however, recommendations on timing of dosing transition of CFTR modulators when CYP3A inhibitors are initiated or discontinued is incomplete. Certain drug interactions may be managed by choosing an alternative treatment to avoid/minimize DDIs. Next generation CFTR modulator therapies under development are expected to provide increased activity with reduced DDI risk.

Genotoxicity of pyrrolizidine alkaloids in metabolically inactive human cervical cancer HeLa cells co-cultured with human hepatoma HepG2 cells

Pyrrolizidine alkaloids (PAs) are secondary plant metabolites, which can be found as contaminant in various foods and herbal products. Several PAs can cause hepatotoxicity and liver cancer via damaging hepatic sinusoidal endothelial cells (HSECs) after hepatic metabolization. HSECs themselves do not express the required metabolic enzymes for activation of PAs. Here we applied a co-culture model to mimic the in vivo hepatic environment and to study PA-induced effects on not metabolically active neighbour cells. In this co-culture model, bioactivation of PA was enabled by metabolically capable human hepatoma cells HepG2, which excrete the toxic and mutagenic pyrrole metabolites. The human cervical epithelial HeLa cells tagged with H2B-GFP were utilized as non-metabolically active neighbours because they can be identified easily based on their green fluorescence in the co-culture. The PAs europine, riddelliine and lasiocarpine induced micronuclei in HepG2 cells, and in HeLa H2B-GFP cells co-cultured with HepG2 cells, but not in HeLa H2B-GFP cells cultured alone. Metabolic inhibition of cytochrome P450 enzymes with ketoconazole abrogated micronucleus formation. The efflux transporter inhibitors verapamil and benzbromarone reduced micronucleus formation in the co-culture model. Furthermore, mitotic disturbances as an additional genotoxic mechanism of action were observed in HepG2 cells and in HeLa H2B-GFP cells co-cultured with HepG2 cells, but not in HeLa H2B-GFP cells cultured alone. Overall, we were able to show that PAs were activated by HepG2 cells and the metabolites induced genomic damage in co-cultured HeLa cells.

What Is Known about Midazolam? A Bibliometric Approach of the Literature

Midazolam is a drug with actions towards the central nervous system producing sedative and anticonvulsants effects, used for sedation and seizures treatments. A better understanding about its effects in the different scenarios presented in the literature could be helpful to gather information regarding its clinical indications, pharmacological interactions, and adverse events. From this perspective, the aim of this study was to analyze the global research about midazolam mapping, specifically the knowledge of the 100 most-cited papers about this research field. For this, a search was executed on the Web of Science-Core Collection database using bibliometric methodological tools. The search strategy retrieved 34,799 articles. A total of 170 articles were evaluated, with 70 articles being excluded for not meeting the inclusion criteria. The 100 most-cited articles rendered 42,480 citations on WoS-CC, ranging from 253 to 1744. Non-systematic review was the most published study type, mainly from North America, during the period of 1992 to 2002. The most frequent keywords were midazolam and pharmacokinetics. Regarding the authors, Thummel and Kunze were the ones with the greatest number of papers included. Our findings showed the global research trends about midazolam, mainly related to its different effects and uses throughout the time.

Identification of Dermatophyte and Non-Dermatophyte Agents in Onychomycosis by PCR and DNA Sequencing—A Retrospective Comparison of Diagnostic Tools

Rapid and reliable fungal identification is crucial to delineate infectious diseases, and to establish appropriate treatment for onychomycosis. Compared to conventional diagnostic methods, molecular techniques are faster and feature higher accuracy in fungal identification. However, in current clinical practice, molecular mycology is not widely available, and its practical applicability is still under discussion. This study summarizes the results of 16,094 consecutive nail specimens with clinical suspicion of onychomycosis. We performed PCR/sequencing on all primary nail specimens for which conventional mycological diagnostics remained inconclusive. In specimens with a positive direct microscopy but negative or contaminated culture, molecular mycology proved superior and specified a fungal agent in 65% (587/898). In 75% (443/587), the identified pathogen was a dermatophyte. Positive cultures for dermatophytes, yeasts and non-dermatophyte molds (NDMs) were concordant with primary-specimen-DNA PCR/sequencing in 83% (10/12), 34% (22/65) and 45% (76/169), respectively. Among NDMs, agreement was high for Fusarium spp. (32/40; 80%), but low for Penicillium spp. (5/25; 20%) and Alternaria spp. (1/20; 5%). This study underlines the improvement in diagnostic yield by fungal primary-specimen-DNA PCR/sequencing in the event of a negative or contaminated culture, as well as its significance for the diagnosis of dermatophyte and non-dermatophyte onychomycosis. Molecular mycology methods like PCR and DNA sequencing should complement conventional diagnostics in cases of equivocal findings, suspected NDM onychomycosis or treatment-resistant nail pathologies.

Biotransformation of phenytoin in the electrochemically-driven CYP2C19 system

The possibility of the detection of atypical kinetic profiles of drug biotransformation using electrochemical systems based on immobilized cytochromes P450 with phenytoin hydroxylation by cytochrome P450 2C19 (CYP2C19) as an example was evaluated for the first time. For this purpose, we developed an electrochemical system, where one of the electrodes was modified by didodecyldimethylammonium bromide (DDAB) and was used as an electron donor for reduction of heme iron ion of the immobilized CYP2C19 and initiation of the catalytic reaction, while the second electrode was not modified and served for an electrochemical quantitation of 4-hydroxyphenytoin, which is a metabolite of antiepileptic drug phenytoin, by its oxidation peak. It was revealed that the dependence of the rate of 4-hydroxyphenytoin formation on phenytoin concentration is described by the equation for two enzymes or two binding sites indicating the existing of high- and low-affinity forms of the enzyme. The atypical kinetics and the kinetic parameters of CYP2C19-mediated phenytoin hydroxylation in the electrochemical system correlate to the same characteristics obtained by other authors in an alternative enzymatic system. Our results demonstrate the possibility of electrochemical systems based on cytochromes P450 to be applied for the detection of atypical kinetic profiles of drug metabolism.

Drug repositioning: Progress and challenges in drug discovery for various diseases

Compared with traditional de novo drug discovery, drug repurposing has become an attractive drug discovery strategy due to its low-cost and high efficiency. Through a comprehensive analysis of the candidates that have been identified with drug repositioning potentials, it is found that although some drugs do not show obvious advantages in the original indications, they may exert more obvious effects in other diseases. In addition, some drugs have a synergistic effect to exert better clinical efficacy if used in combination. Particularly, it has been confirmed that drug repositioning has benefits and values on the current public health emergency such as the COVID-19 pandemic, which proved the great potential of drug repositioning. In this review, we systematically reviewed a series of representative drugs that have been repositioned for different diseases and illustrated successful cases in each disease. Especially, the mechanism of action for the representative drugs in new indications were explicitly explored for each disease, we hope this review can provide important insights for follow-up research.

Skeletal Infections Caused by Coccidioides Species

Background: Coccidioidomycosis represents an endemic and challenging disease, with rare extrapulmonary manifestations. The present review of all published cases of core and extremities osseous coccidioidomycosis aims to describe epidemiology, patients’ characteristics, symptoms as well as medical and surgical treatment options and their effectiveness. Methods: A thorough review of all published skeletal core and extremity infections due to Coccidioides species was conducted. Information regarding demographics, causative fungus, antifungal treatment (AFT), surgical management as well as the infection outcome was recorded. Results: A total of 92 cases of Coccidioides spp. skeletal infections were recorded in 87 patients. The patients’ mean age was 35.3 years. The most common site of infection was the spine (82.6%), followed by the foot (6.5%), while the predominant symptom upon presentation was pain (29.9%). Immunosuppressive conditions and/or medications were observed in 21 patients (24.1%). Regarding imaging methods, indicating diagnosis, plain X-rays or CT scans were performed in most patients (50.6%), followed by magnetic resonance imaging (MRI) (47.1%). Most cases were diagnosed through histopathology (62; 71.3%), followed by serology testing (36; 42.4%) and by cultures (35; 40.2%). In 32 cases (36.8%), Coccidioides immitis was cultured, while in the remaining 55 cases (63.2%) the fungus was not further characterized. Regarding AFT, amphotericin B was the preferred agent (52.9%), followed by fluconazole (43.3%). In most cases (78.2%) surgical treatment was also performed. Treatment was successful in 80.5% of cases. Conclusions: Skeletal core and extremity infections due to Coccidioides spp. represent a severe disease. With the available data, the combination of prolonged proper AFT with surgical intervention seems to be the optimal current therapeutic approach.

Use of Modeling and Simulation to Predict the Influence of Triazole Antifungal Agents on the Pharmacokinetics of Crizotinib

Crizotinib is used for the treatment of c-ros oncogene 1-positive advanced non-small-cell lung cancer. Triazole antifungal agents are widely used for invasive fungal infections in clinical practice. To predict the potential influence of different triazoles (voriconazole, fluconazole, and itraconazole) on the pharmacokinetics of crizotinib by modeling and simulation the physiologically based pharmacokinetic models were established and validated in virtual cancer subjects through Simcyp software based on the essential physicochemical properties and pharmacokinetic data collected. The validated physiologically based pharmacokinetic models were applied to predict the drug-drug interactions between crizotinib and different triazoles (voriconazole, fluconazole, or itraconazole) in patients with cancer. Crizotinib and triazole antifungal agents were administered orally. The predicted plasma concentration vs time profiles of crizotinib, voriconazole, fluconazole, and itraconazole showed good agreement with observed, respectively. The geometric mean area under the plasma concentration-time curve (AUC) of crizotinib was increased by 84%, 58%, and 79% when coadministered with voriconazole, fluconazole, or itraconazole at multiple doses, respectively. The drug-drug interaction results showed increased pharmacokinetic exposure (maximum plasma concentration and area under the plasma concentration-time curve) of crizotinib when coadministrated with different triazoles (voriconazole > itraconazole > fluconazole). Among the 3 triazoles, voriconazole exhibited the most significant influence on the pharmacokinetic exposure of crizotinib. In clinic, adverse drug reactions and toxicity related to crizotinib should be carefully monitored, and therapeutic drug monitoring for crizotinib is recommended to guide dosing and optimize treatment when coadministered with voriconazole, fluconazole, or itraconazole.

Using TKTD Models in Combination with In Vivo Enzyme Inhibition Assays to Investigate the Mechanisms behind Synergistic Interactions across Two Species

The aim of this study is to compare the azole synergy across an insect, Chironomus riparius, and a crustacean species, Daphnia magna. We use a combination of in vivo measurements of cytochrome P450 monooxygenase (CYP) biotransformation potential and toxicokinetic (TK) and toxicodynamic (TD) modeling to understand the mechanism behind the synergy of two azole fungicides: the imidazole prochloraz and the triazole propiconazole on the pyrethroid insecticide α-cypermethrin. For both species, the synergistic effect of prochloraz was well-described by its effect on in vivo CYP activity, which corresponded to the biotransformation rate of the TK model parameterized on the survival data of the mixture experiment. For propiconazole, however, there were 100-fold and 50-fold differences between the 50% effect concentration of in vivo CYP activity and the modeled biotransformation rate for C. riparius and D. magna, respectively. Propiconazole, therefore, seems to induce synergy through a mechanism that cannot be quantified solely by the CYP activity assay used in this study in either of the two species. We discuss the differences between prochloraz and propiconazole as synergists across the two species in the light of the type and time dynamics of affected biotransformation processes.

Cytochrome P450 1A2 is the most important enzyme for hepatic metabolism of the metamizole metabolite 4-methylaminoantipyrine

Aims

Metamizole (dipyrone) is a prodrug not detectable in serum or urine after oral ingestion. The primary metabolite, 4‐methylaminoantipyrine (4‐MAA), can be N‐demethylated to 4‐aminoantipyrine (4‐AA) or oxidized to 4‐formylaminoantipyrine (4‐FAA) by cytochrome P450 (CYP)‐dependent reactions. We aimed to identify the CYPs involved in 4‐MAA metabolism and to quantify the effect of CYP inhibition on 4‐MAA metabolism.

Methods

We investigated the metabolism of 4‐MAA in vitro using CYP expressing supersomes and the pharmacokinetics of metamizole in the presence of CYP inhibitors in male subjects.

Results

The experiments in supersomes revealed CYP1A2 as the major CYP for 4‐MAA N‐demethylation and 4‐FAA formation with CYP2C19 and CYP2D6 contributing to N‐demethylation. In the clinical study, we investigated the influence of ciprofloxacin (CYP1A2 inhibitor), fluconazole (CYP2C19 inhibitor) and the combination ciprofloxacin/fluconazole on the pharmacokinetics of metamizole in n = 12 male subjects in a randomized, placebo‐controlled, double‐blind study. The geometric mean ratios for the area under the concentration–time curve of 4‐MAA after/before treatment were 1.17 (90% CI 1.09–1.25) for fluconazole, 1.51 (90% CI 1.42–1.60) for ciprofloxacin and 1.92 (90% CI 1.81–2.03) for ciprofloxacin/fluconazole. Fluconazole increased the half‐life of 4‐MAA from 3.22 hours by 0.47 hours (95% CI 0.13–0.81, P < .05), ciprofloxacin by 0.69 hours (95% CI 0.44–0.94, P < .001) and fluconazole/ciprofloxacin by 2.85 hours (95% CI 2.48–3.22, P < .001).

Conclusion

CYP1A2 is the major CYP for the conversion of 4‐MAA to 4‐AA and 4‐FAA. The increase in 4‐MAA exposure by the inhibition of CYP1A2 and by the combination CYP1A2/CYP2C19 may be relevant for dose‐dependent adverse reactions of 4‐MAA.

Discovery of Novel Acetamide-Based Heme Oxygenase-1 Inhibitors with Potent In Vitro Antiproliferative Activity

Heme oxygenase-1 (HO-1) promotes heme catabolism exercising cytoprotective roles in normal and cancer cells. Herein, we report the design, synthesis, molecular modeling, and biological evaluation of novel HO-1 inhibitors. Specifically, an amide linker in the central spacer and an imidazole were fixed, and the hydrophobic moiety required by the pharmacophore was largely modified. In many tumors, overexpression of HO-1 correlates with poor prognosis and chemoresistance, suggesting the inhibition of HO-1 as a possible antitumor strategy. Accordingly, compounds 7i and 7l-p emerged for their potency against HO-1 and were investigated for their anticancer activity against prostate (DU145), lung (A549), and glioblastoma (U87MG, A172) cancer cells. The selected compounds showed the best activity toward U87MG cells. Compound 7l was further investigated for its in-cell enzymatic HO-1 activity, expression levels, and effects on cell invasion and vascular endothelial growth factor (VEGF) extracellular release. The obtained data suggest that 7l can reduce cell invasivity acting through modulation of HO-1 expression.

Failure of Warfarin Anticoagulation Therapy after Administration of Oral Terbinafine

Warfarin is widely used anticoagulant drug for a variety of diseases (thromboembolic disease, atrial fibrillation, etc.). It has three most important parallel metabolic pathways, CYP1A2, CYP3A4 and CYP2C9. Terbinafine is a potent CYP2D6 inhibitor. A possible drug interaction could lead to an increased pharmacological effect of the above drugs. Enzyme induction with CYP3A4, CYP2C9, CYP1A2 inducers may have occurred. Case report: We present a case report of an 88-year-old male patient who has been successfully anticoagulated with warfarin due to atrial fibrillation. He was orally administered terbinafine to treat onychomycosis. Two weeks after initiation of this drug the patient experienced dizziness and feelings of instability, for which he was admitted to the neurology department. A low-efficient INR level was found at the baseline, presumably due to warfarin interaction with terbinafine. The induction of liver enzymes lasts 10-14 days, which matches the introduction of the antifungal agent. Conclusion: Combined therapy with warfarin and oral terbinafine is actually rarely prescribed but, if used, their interaction can have serious consequences in many clinical situations for which anticoagulation therapy with warfarin is indicated.

An adverse outcome pathway on the disruption of retinoic acid metabolism leading to developmental craniofacial defects

Adverse outcome pathway (AOP) is a conceptual framework that links a molecular initiating event (MIE) via intermediate key events (KEs) with adverse effects (adverse outcomes, AO) relevant for risk assessment, through defined KE relationships (KERs). The aim of the present work is to describe a linear AOP, supported by experimental data, for skeletal craniofacial defects as the AO. This AO was selected in view of its relative high incidence in humans and the suspected relation to chemical exposure. We focused on inhibition of CYP26, a retinoic acid (RA) metabolizing enzyme, as MIE, based on robust previously published data. Conazoles were selected as representative stressors. Intermediate KEs are RA disbalance, aberrant HOX gene expression, disrupted specification, migration, and differentiation of neural crest cells, and branchial arch dysmorphology. We described the biological basis of the postulated events and conducted weight of evidence (WoE) assessments. The biological plausibility and the overall empirical evidence were assessed as high and moderate, respectively, the latter taking into consideration the moderate evidence for concordance of dose-response and temporal relationships. Finally, the essentiality assessment of the KEs, considered as high, supported the robustness of the presented AOP. This AOP, which appears of relevance to humans, thus contributes to mechanistic underpinning of selected test methods, thereby supporting their application in integrated new approach test methodologies and strategies and application in a regulatory context.

Evaluation of Ipatasertib Interactions with Itraconazole and Coproporphyrin I and III in a Single Drug Interaction Study in Healthy Subjects

Ipatasertib is a pan-AKT inhibitor in development for the treatment of cancer. Ipatasertib was metabolized by CYP3A4 to its major metabolite, M1 (G-037720), and was a P-gp substrate and OATP1B1/1B3 inhibitor in vitro. A phase I drug-drug interaction (DDI) study (n = 15) was conducted in healthy subjects to evaluate the effect of itraconazole (200-mg solution QD, 4 days), a strong CYP3A4 and P-gp inhibitor, on pharmacokinetics of ipatasertib (100-mg single dose). Itraconazole increased the C_max and AUC_{0 -∞} of ipatasertib by 2.3- and 5.5-fold, respectively, increased the half-life by 53%, and delayed the t_max by 1 hour. The C_max and AUC_0-72h of its metabolite M1 (G-037720) reduced by 91% and 68%, respectively. This study confirmed that CYP3A4 plays a major role in ipatasertib clearance. Furthermore, the interaction of ipatasertib with coproporphyrin (CP) I and CPIII, the two endogenous substrates of OATP1B1/1B3, was evaluated in this study. CPI and CPIII plasma levels were unchanged in the presence of ipatasertib, both at exposures of 100 mg and at higher exposures in combination with itraconazole. This indicated no in vivo inhibition of OATP1B1/1B3 by ipatasertib. Additionally, it was shown that CPI and CPIII were not P-gp substrates in vitro, and itraconazole had no effect on CPI and CPIII concentrations in vivo. The latter is an important finding because it will simplify interpretation of future DDI studies using CPI/CPIII as OATP1B1/1B3 biomarkers. SIGNIFICANCE STATEMENT: This drug-drug interaction study in healthy volunteers demonstrated that CYP3A4 plays a major role in ipatasertib clearance, and that ipatasertib is not an organic anion transporting polypeptide 1B1/1B3 inhibitor. Furthermore, it was demonstrated that itraconazole, an inhibitor of CYP3A4 and several transporters, did not affect CPI/CPIII levels in vivo. This increases the understanding and application of these endogenous substrates as well as itraconazole in complex drug interaction studies.

Drug-drug interactions between vitamin K antagonists and statins: a systematic review

PURPOSE

Concomitant use of vitamin K antagonists (VKA) and statins is frequent in cardiovascular patients. However, clinical guidelines on this drug combination are divergent. Therefore, we performed a systematic review to evaluate the effect of statin initiation on coagulation among VKA users.

METHODS

Following the PRISMA guidelines, we applied two broad search strategies for the drug interaction between VKA and statins in both Embase and Pubmed; 8623 unique hits were obtained. In the final sample, eight studies were included.

RESULTS

The most frequently used VKA in the studies was warfarin, while simvastatin was the most commonly initiated statin. All included studies showed a minor increase in the anticoagulant effect of VKA following statin initiation during VKA treatment. The reported increases in mean international normalized ratio (INR) ranged from 0.15-0.65.

CONCLUSION

The anticoagulant effect of statin initiation in patients treated with VKA is likely to be of limited clinical relevance but should be evaluated individually.

Genotoxicity of selected pyrrolizidine alkaloids in human hepatoma cell lines HepG2 and Huh6

INTRODUCTION

Pyrrolizidine alkaloids (PAs) are found in many plant species as secondary metabolites which affect humans via contaminated food sources, herbal medicines and dietary supplements. Hundreds of compounds belonging to PAs have been identified. PAs undergo hepatic metabolism, after which they can induce hepatotoxicity and carcinogenicity. Many aspects of their mechanism of carcinogenicity are still unclear and it is important for human risk assessment to investigate this class of compounds further.

MATERIAL AND METHODS

Human hepatoma cells HepG2 were used to investigate the genotoxicity of different chemical structural classes of PAs, namely europine, lycopsamine, retrorsine, riddelliine, seneciphylline, echimidine and lasiocarpine, in the cytokinesis-block micronucleus (CBMN) assay. The different ester type PAs europine, seneciphylline, and lasiocarpine were also tested in human hepatoma Huh6 cells. Six different PAs were investigated in a crosslink comet assay in HepG2 cells.

RESULTS

The maximal increase of micronucleus formation was for all PAs in the range of 1.64-2.0 fold. The lowest concentrations at which significant induction of micronuclei were found were 3.2 μM for lasiocarpine and riddelliine, 32 μM for retrorsine and echimidine, and 100 μM for seneciphylline, europine and lycopsamine. Significant induction of micronuclei by lasiocarpine, seneciphylline, and europine were achieved in Huh6 cells at similar concentrations. Reduced tail formation after hydrogen peroxide treatment was found in the crosslink comet assay for all diester type PAs, while an equimolar concentration of the monoesters europine and lycopsamine did not significantly reduce DNA migration.

CONCLUSION

The widely available human hepatoma cell lines HepG2 and Huh6 were suitable for the assessment of PA-induced genotoxicity. Selected PAs confirmed previously published potency rankings in the micronucleus assay. In HepG2 cells, the crosslinking activity was related to the ester type, which is a first report of PA mediated effects in the comet assay.

New insights into quetiapine metabolism using molecular networking

Metabolism is involved in both pharmacology and toxicology of most xenobiotics including drugs. Yet, visualization tools facilitating metabolism exploration are still underused, despite the availibility of pertinent bioinformatics solutions. Since molecular networking appears as a suitable tool to explore structurally related molecules, we aimed to investigate its interest in in vitro metabolism exploration. Quetiapine, a widely prescribed antipsychotic drug, undergoes well-described extensive metabolism, and is therefore an ideal candidate for such a proof of concept. Quetiapine was incubated in metabolically competent human liver cell models (HepaRG) for different times (0 h, 3 h, 8 h, 24 h) with or without cytochrom P450 (CYP) inhibitor (ketoconazole as CYP3A4/5 inhibitor and quinidine as CYP2D6 inhibitor), in order to study its metabolism kinetic and pathways. HepaRG culture supernatants were analyzed on an ultra-high performance liquid chromatography coupled with tandem mass spectrometry (LC-HRMS/MS). Molecular networking approach on LC-HRMS/MS data allowed to quickly visualize the quetiapine metabolism kinetics and determine the major metabolic pathways (CYP3A4/5 and/or CYP2D6) involved in metabolite formation. In addition, two unknown putative metabolites have been detected. In vitro metabolite findings were confirmed in blood sample from a patient treated with quetiapine. This is the first report using LC-HRMS/MS untargeted screening and molecular networking to explore in vitro drug metabolism. Our data provide new evidences of the interest of molecular networking in drug metabolism exploration and allow our in vitro model consistency assessment.

Potential Drug-Drug Interactions with Combination Volasertib + Itraconazole: A Phase I, Fixed-sequence Study in Patients with Solid Tumors

PURPOSE

This drug-drug interaction study determined whether the metabolism and distribution of the Polo-like kinase 1 inhibitor, volasertib, is affected by co-administration of the P-glycoprotein and cytochrome P-450 3A4 inhibitor, itraconazole.

METHODS

This was an uncontrolled, open-label, fixed-sequence trial of two 21-day treatment cycles in patients with various solid tumors. In cycle 1 (test), eligible patients were administered volasertib (day 1) plus itraconazole (days -3 to 15). In cycle 2 (reference), patients received volasertib monotherapy. The primary end point was the influence of co-administration of itraconazole on the pharmacokinetic profile (AUC0-tz; Cmax) of volasertib and its main metabolite, CD 10899, compared with that of volasertib monotherapy. Other end points included tolerability and preliminary therapeutic efficacy.

FINDINGS

Concurrent administration of itraconazole resulted in a slight reduction in the AUC0-tz (geometric mean ratio, 93.6%; 90% CI, 82.1%-106.8%) and a 20% reduction in Cmax (geometric mean ratio, 79.4%; 90% CI, 64.9%-97.1%) of volasertib compared with monotherapy. Of note, concurrent administration of itraconazole + volasertib had no effect on the AUC0-∞ of volasertib. More patients reported at least one drug-related adverse event in cycle 1 than in cycle 2 (75% vs 71%). The most commonly reported drug-related adverse events (cycles 1 and 2) were thrombocytopenia (68% and 33%, respectively), leukopenia (50% and 46%), and anemia (36% and 33%). No objective responses were observed. Stable disease was observed in 25 of 28 patients (89%).

IMPLICATIONS

While there was no clear evidence of a pharmacokinetic interaction between volasertib and itraconazole, co-administration reduced the tolerability of volasertib. Clinicaltrials.gov identifier: NCT01772563.

Immortalization of human hepatocytes from biliary atresia with CDK4R24C, cyclin D1, and TERT for cytochrome P450 induction testing

Hepatocytes are an important tool for in vitro toxicology testing. In addition to primary cultures, a limited number of immortalized cell lines have been developed. We here describe a new cell line, designated as HepaMN, which has been established from a liver associated with biliary atresia. Hepatocytes were isolated from a liver of 4-year-old girl with biliary atresia and immortalized by inoculation with CSII-CMV-TERT, CSII-CMV-Tet-Off, CSII-TRE-Tight-cyclin D1 and CSII-TRE-Tight-CDK4^R24C (mutant CDK4: an INK4a-resistant form of CDK4) lentiviruses at the multiplicity of infection of 3 to 10. HepaMN cells exhibited morphological homogeneity, displaying hepatocyte-like phenotypes. Phenotypic studies in vivo and in vitro revealed that HepaMN cells showed polarized and functional hepatocyte features along with a canalicular cell phenotype under defined conditions, and constitutively expressed albumin and carbamoyl phosphate synthetase I in addition to epithelial markers. Since HepaMN cells are immortal and subcloned, kinetics and expression profiles were independent of population doublings. HepaMN cells showed increased CYP3A4 expression after exposure to rifampicin, implying that their close resemblance to normal human hepatocytes makes them suitable for research applications including drug metabolism studies.

Associations between plasma hydroxylated metabolite of itraconazole and serum creatinine in patients with a hematopoietic or immune-related disorder

PURPOSE

Serum markers of renal function have not been characterized in patients treated with itraconazole (ITZ). This study aimed to evaluate the associations between plasma ITZ and its hydroxylated metabolite (OH-ITZ) concentrations and serum markers of renal function in patients with hematopoietic or immune-related disorder.

METHODS

This study enrolled 40 patients with hematopoietic or immune-related disorder who are receiving oral ITZ solution. Plasma concentrations of ITZ and OH-ITZ at 12 h after dosing were determined at steady state. Their relationships with serum levels of creatinine and cystatin C and their estimated glomerular filtration rate (eGFR) were evaluated.

RESULTS

The free plasma concentration of ITZ had no correlation with serum creatinine and serum creatinine-based estimated glomerular filtration rate (eGFR-cre). The free plasma concentration of OH-ITZ was positively and negatively correlated with serum creatinine and eGFR-cre, respectively. The free plasma concentrations of ITZ and OH-ITZ had no association with serum cystatin C and serum cystatin C-based eGFR. Serum creatinine was higher by 16% after than before starting ITZ treatment, while eGFR-cre was lower by 9.3%. The serum creatinine ratio after/before ITZ treatment was positively correlated with the free plasma concentration of OH-ITZ. The patients co-treated with trimethoprim-sulfamethoxazole had higher serum creatinine. Concomitant glucocorticoid administration did not significantly alter serum cystatin C.

CONCLUSIONS

Patients with hematopoietic or immune-related disorder treated with oral ITZ had a higher level of serum creatinine. Although serum creatinine potentially increases in conjunction with the free plasma concentration of OH-ITZ, concomitant ITZ administration has a slight impact on the eGFR-cre level in clinical settings.

Optimising Seniors' Metabolism of Medications and Avoiding Adverse Drug Events Using Data on How Metabolism by Their P450 Enzymes Varies with Ancestry and Drug-Drug and Drug-Drug-Gene Interactions

Many individuals ≥65 have multiple illnesses and polypharmacy. Primary care physicians prescribe >70% of their medications and renew specialists’ prescriptions. Seventy-five percent of all medications are metabolised by P450 cytochrome enzymes. This article provides unique detailed tables how to avoid adverse drug events and optimise prescribing based on two key databases. DrugBank is a detailed database of 13,000 medications and both the P450 and other complex pathways that metabolise them. The Flockhart Tables are detailed lists of the P450 enzymes and also include all the medications which inhibit or induce metabolism by P450 cytochrome enzymes, which can result in undertreatment, overtreatment, or potentially toxic levels. Humans have used medications for a few decades and these enzymes have not been subject to evolutionary pressure. Thus, there is enormous variation in enzymatic functioning and by ancestry. Differences for ancestry groups in genetic metabolism based on a worldwide meta-analysis are discussed and this article provides advice how to prescribe for individuals of different ancestry. Prescribing advice from two key organisations, the Dutch Pharmacogenetics Working Group and the Clinical Pharmacogenetics Implementation Consortium is summarised. Currently, detailed pharmacogenomic advice is only available in some specialist clinics in major hospitals. However, this article provides detailed pharmacogenomic advice for primary care and other physicians and also physicians working in rural and remote areas worldwide. Physicians could quickly search the tables for the medications they intend to prescribe.

Invasive fungal diseases in patients with new diagnosed acute lymphoblastic leukaemia

BACKGROUND

Patients with acute leukaemia have a high incidence of fungal infections. This has primarily been shown in acute myeloid leukaemia and is different for acute lymphoblastic leukaemia. Until now no benefit of mould active prophylaxis has been demonstrated in the latter population.

METHODS

In this retrospective single-centre study, we analysed the incidence, clinical relevance, and outcome of invasive fungal diseases (IFD) as well as the impact of antifungal prophylaxis for the first 100 days following the primary diagnosis of acute lymphoblastic leukaemia.

RESULTS

In 58 patients a high rate of proven, probable, and possible fungal infections could be demonstrated with a 3.4%, 8.6%, and 17.2% likelihood, respectively. The incidence might be even higher, as nearly 40% of all patients had no prolonged neutropenia for more than 10 days, excluding those from the European Organization of Research and Treatment of cancer and the Mycoses Study Group criteria for probable invasive fungal disease. The diagnosed fungal diseases had an impact on the duration of hospitalisation, which was 13 days longer for patients with proven/probable IFD compared to patients with no signs of fungal infection. Use of antifungal prophylaxis did not significantly affect the risk of fungal infection.

CONCLUSION

Patients with acute lymphoblastic leukaemia are at high risk of acquiring an invasive fungal disease. Appropriate criteria to define fungal infections, especially in this population, and strategies to reduce the risk of infection, including antifungal prophylaxis, need to be further evaluated.

Characterization of a long-term mouse primary liver 3D tissue model recapitulating innate-immune responses and drug-induced liver toxicity

Three-dimensional liver in vitro systems have recently attracted a lot of attention in drug development. These systems help to gain unprecedented insights into drug-induced liver injury (DILI), as they more closely reproduce liver biology, and as drug effects can be studied in isolated and controllable microenvironments. Many groups established human-based in vitro models but so far neglected the animal equivalent, although the availability of both models would be desirable. Animal in vitro models enable back- and forward translation of in vitro and in vivo findings, bridge the gap between rodent in vivo and human in vitro scenarios, and ultimately support the interpretation of data generated with preclinical species and humans. Since mice are often used in drug development and physiologically relevant in vitro systems are lacking, we established, for the first time, a mouse liver model that encompasses primary parenchymal and non-parenchymal cells with preserved viability and functionality over three weeks. Using our three-dimensional liver spheroids, we were able to predict the toxicity of known DILI compounds, demonstrated the interaction cascades between the different cell types and showed evidence of drug-induced steatosis and cholestasis. In summary, our mouse liver spheroids represent a valuable in vitro model that can be applied to study DILI findings, reported from mouse studies, and offers the potential to detect immune-mediated drug-induced liver toxicity.

Calmodulin inhibition as a mode of action of antifungal imidazole pharmaceuticals in non-target organisms

To improve assessment of risks associated with pharmaceutical contamination of the environment, it is crucial to understand effects and mode of action of drugs in non-target species. The evidence is accumulating that species with well-conserved drug targets are prone to be at risk when exposed to pharmaceuticals. An interesting group of pharmaceuticals released into the environment is imidazoles, antifungal agents with inhibition of ergosterol synthesis as a primary mode of action in fungi. However, imidazoles have also been identified as competitive antagonists of calmodulin (CaM), a calcium-binding protein with phylogenetically conserved structure and function. Therefore, imidazoles would act as CaM inhibitors in various organisms, including those with limited capacity to synthesize sterols, such as arthropods. We hypothesized that effects observed in crustaceans exposed to imidazoles are related to the CaM inhibition and CaM-dependent nitric oxide (NO) synthesis. To test this hypothesis, we measured (i) CaM levels and its gene expression, (ii) NO accumulation and (iii) gene expression of NO synthase (NOS1 and NOS2), in the cladoceran Daphnia magna exposed to miconazole, a model imidazole drug. Whereas significantly increased CaM gene expression and its cellular allocation were observed, supporting the hypothesized mode of action, no changes occurred in either NO synthase expression or NO levels in the exposed animals. These findings suggest that CaM inhibition by miconazole leads to protein overexpression that compensates for the loss in the protein activity, with no measurable downstream effects on NO pathways. The inhibition of CaM in D. magna may have implications for effect assessment of exposure to mixtures of imidazoles in aquatic non-target species.

Drug-drug interaction between warfarin and statins: A Danish cohort study

Initiation of statin treatment is suggested to increase the international normalised ratio (INR) among warfarin users. However, available data is limited and conflicting. We conducted a register-based cohort study to evaluate the drug-drug interaction between warfarin and statins. By linking data on INR measurements and filled prescriptions, we identified warfarin users 2000-2015 initiating simvastatin (n = 1363), atorvastatin (n = 165) or rosuvastatin (n = 23). Simvastatin initiation led to an increase in mean INR from 2.40 to 2.71, with INRs peaking after 4 weeks, corresponding to a mean change of 0.32 (95%CI 0.25-0.38). High-dose and low-dose simvastatin led to comparable changes (mean change 0.33 vs 0.29). Initiation of atorvastatin and rosuvastatin lead to INR increases of 0.27 (95%CI 0.12-0.42) and 0.30 (95%CI -0.09-0.69). In conclusion, initiation of simvastatin, atorvastatin or rosuvastatin among warfarin users led to a minor increase in INR. The magnitude of this change is for most patients likely of limited clinical relevance.

Pharmacokinetic Drug Interactions of an Orally Available TRH Analog (Rovatirelin) With a CYP3A4/5 and P-Glycoprotein Inhibitor (Itraconazole)

The effects of itraconazole on the pharmacokinetics of rovatirelin were investigated in an open-label, single-sequence drug-drug interaction study in 16 healthy subjects. Subjects were administered a single oral dose of rovatirelin (1.6 mg) on day 1 and day 15. From day 8 through 16, subjects received daily oral doses of itraconazole (200 mg/day). Concentrations of rovatirelin and (thiazolylalanyl)methylpyrrolidine (TAMP), the major metabolite of rovatirelin formed by cytochrome P450 (CYP) 3A4/5, were determined in plasma and urine. Pharmacokinetic parameters were used to evaluate the drug-drug interaction potential of rovatirelin as a victim. With coadministration, maximum concentration (C_max ) and area under the concentration-time curve extrapolated to infinity (AUC_inf ) of rovatirelin increased 3.05-fold and 2.82-fold, respectively, and the 90% confidence intervals of the ratios for C_max (2.64-3.52) and AUC_inf (2.47-3.23) did not fall within the 0.8-1.25 boundaries. Urinary excretion of rovatirelin increased at almost the same ratio as the AUC_inf ratio with coadministration; however, renal clearance did not change. C_max , AUC_inf , and urinary excretion of TAMP were decreased by coadministration. Itraconazole has the potential to inhibit drug transport via intestinal P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP); therefore, substrate assessments of rovatirelin for the 2 transporters were evaluated using Caco-2 cell monolayers. In vitro studies showed that rovatirelin is a substrate for P-gp but not for BCRP. The current study shows that itraconazole's effect on rovatirelin pharmacokinetics is mediated through inhibition of CYP3A4/5 and intestinal P-gp.

Effects of the dietary inclusion of a probiotic or prebiotic on florfenicol pharmacokinetic profile in broiler chicken

We evaluated the effect of prebiotic or probiotic as feed additives on florfenicol kinetic in broilers feed. Unsexed two hundred, thirty-five-day-old broiler chickens, were put in four equal groups (n = 50). The first group was administrated florfenicol intravenous at 30 mg/kg body weight (BW) only once dosage without pre- or probiotic administration to determine the bioavailability. While, the second group was administrated florfenicol (intracrop routes; a dosage of 30 mg/kg BW for five progressive days) without pre- or probiotic co-administration. The third and the fourth groups were administrated the same dose of florfenicol (intracrop route) for five successive days, followed by 10 days of prebiotic or probiotic treatment respectively. The plasma florfenicol % was identified by high-pressure liquid chromatography (HPLC) after the first florfenicol administration (intravenous or intracrop routes) in all groups. Then, the residual levels of florfenicol were determined in liver, kidney and muscle tissues from the second, third and fourth groups which were exposed to florfenicol orally. Our results demonstrated that broilers pre-treated with prebiotic or probiotic significantly increased C_max , AUC_{0- t} , AUC_0-inf as well as AUMC values, while significant drop was recorded in V/F and CL/F. Prebiotic or probiotic influenced the cumulative effect of florfenicol in liver and kidney tissues of treated birds.

Histoplasma capsulatum presenting as generalized lymphadenopathy after renal transplantation

Histoplasma capsulatum is typically an indolent disease among immunocompetent patients. However, immunocompromised patients, such as solid organ transplant recipients, are at risk of developing severe histoplasmosis. Yet post-transplant histoplasmosis is a rare pathology, representing less than five percent of invasive fungal infections among transplant recipients. Furthermore, patients tend to present with nonspecific clinical symptoms, complicating timely diagnosis and delaying treatment. Disease features that may be more representative of H. capsulatum infection, such as anemia, leukopenia and pulmonary involvement are often not present until late in the disease course, when the patient is at greater risk of decompensation. Unlike H. capsulatum infections among immunocompetent hosts, extrapulmonary infection among immunocompromised hosts is more the rule than the exception. Treatment with liposomal amphotericin B followed by oral itraconazole is the standard therapy, but special considerations must be made for patients with hepatic and/or renal insufficiency, underlying cardiac abnormalities or malabsorptive pathologies and doses of immunosuppressants will need to be adjusted for drug interactions. Herein we present a case of H. capsulatum infection presenting with generalized lymphadenopathy post-renal transplant.

Drug-Drug Interactions of P-gp Substrates Unrelated to CYP Metabolism

BACKGROUND

Recent US Food and Drug Administration (FDA) draft guidance on pharmacokinetic drugdrug interactions (DDIs) has highlighted the clinical importance of ABC transporters B1 or P-glycoprotein (P-gp), hepatic organic anion-transporting polypeptide transporters and breast cancer resistant protein because of their broad substrate specificity and the potential to be involved in DDIs. This guidance has indicated that digoxin, dabigatran etexilate and fexofenadine are P-gp substrate drugs and has defined P-gp inhibitors as those that increase the AUC of digoxin by ≧1.25-fold in clinical DDI studies. However, when substrate drugs of both CYPs and P-gp are involved in DDIs, it remains that the mechanisms of DDIs will be quite ambiguous in assessing how much the CYPs and/or drug transporters partially contribute to DDIs.

OBJECTIVE

Since there are no detailed manuscripts that summarizes P-gp interactions unrelated to CYP metabolism, this article reviews the effects of potent P-gp inhibitors and P-gp inducers on the pharmacokinetics of P-gp substrate drugs, including digoxin, talinolol, dabigatran etexilate, and fexofenadine in human studies. In addition, the present outcome were to determine the PK changes caused by DDIs among P-gp substrate drugs without CYP metabolism in human DDI studies.

CONCLUSION

Our manuscript concludes that the PK changes of the DDIs among P-gp drugs unrelated to CYP metabolism are less likely to be serious, and it appears to be convincing that the absences of clinical effects caused to the PK changes by the P-gp inducers is predominant compared with the excessive effects caused to those by the P-gp inhibitors.

Aspects of vincristine-induced neuropathy in hematologic malignancies: a systematic review

PURPOSE

Vincristine is widely used as anticancer therapy for a variety of hematological malignancies. The treatment is limited by progressive vincristine-induced neuropathy, possibly including both peripheral sensory and motor nerves, autonomic nervous functions, and the central nervous system. This dose-limiting side-effect can diminish quality of life and, furthermore, cause discontinuation of vincristine treatment. The present review elucidates the current knowledge regarding vincristine-induced neuropathy in hematologic malignancies, focusing on neuropathy assessment, clinical and molecular predictive markers, drug-drug interference, prevention, and treatment.

METHODS

This review is conducted by a systematic search strategy for the identification of relevant literature in the PubMed and Embase databases.

RESULTS

No clinical parameters displayed convincing potential as predictors of vincristine-induced neuropathy; however, preexisting neuropathy was consistently reported to be associated with an increased risk of neurotoxicity. In contrast, molecular markers, including polymorphisms in genes involved in the pharmacodynamics and pharmacokinetics of vincristine, displayed great potential as predictive markers of neuropathy incidence and severity. Furthermore, antifungal drugs, such as itraconazole and voriconazole, decrease the metabolism of vincristine and consequently lead to severe neuropathy when co-administered with vincristine, underscoring why fluconazole should be the antifungal drug of choice.

CONCLUSION

Reports from the 71 included studies clearly emphasize the lack of consistency in neuropathy assessment, grading systems, and reporting, making it difficult to interpret results between studies. Thus, truer clinical and molecular markers could emerge if the consistency of neuropathy detection and reporting increases by the use of conventional standardized neuropathy assessment tools and grading scales.

Clinical applications of small molecule inhibitors of Pregnane X receptor

The canonical effect of Pregnane X Receptor (PXR, NR1I2) agonism includes enhanced hepatic uptake and a concomitant increase in the first-pass metabolism and efflux of drugs in mammalian liver and intestine. In patients undergoing combination therapy, PXR-mediated gene regulation represents the molecular basis of numerous food-drug, herb-drug, and drug-drug interactions. Moreover, PXR activation promotes chemotherapeutic resistance in certain malignancies. Additional research efforts suggest that sustained PXR activation exacerbates the development of fatty liver disease. Additional metabolic effects of PXR activation in liver are the inhibition of fatty acid oxidation and gluconeogenesis. The identification of non-toxic and selective PXR antagonists is therefore of current research interest. Inhibition of PXR should decrease adverse effects, improve therapeutic effectiveness, and advance clinical outcomes in patients with cancer, fatty liver, and diabetes. This review identifies small molecule PXR antagonists described to date, discusses possible molecular mechanisms of inhibition, and seeks to describe the likely biomedical consequences of the inhibition of this nuclear receptor superfamily member.

A Bright Future for Fluorescence Imaging of Fungi in Living Hosts

Traditional in vivo investigation of fungal infection and new antifungal therapies in mouse models is usually carried out using post mortem methodologies. However, biomedical imaging techniques focusing on non-invasive techniques using bioluminescent and fluorescent proteins have become valuable tools. These new techniques address ethical concerns as they allow reduction in the number of animals required to evaluate new antifungal therapies. They also allow better understanding of the growth and spread of the pathogen during infection. In this review, we concentrate on imaging technologies using different fungal reporter proteins. We discuss the advantages and limitations of these different reporters and compare the efficacy of bioluminescent and fluorescent proteins for fungal research.

The synergistic potential of azole fungicides does not directly correlate to the inhibition of cytochrome P450 activity in aquatic invertebrates

The ability of azole fungicides to inhibit cytochrome P450 dependent metabolism is proposed to be the main mechanism for their synergizing effect on pyrethroid insecticide toxicity in aquatic invertebrates. This study investigates the correlation between inhibition strength and synergistic potential of azole fungicides in the crustacean Daphnia magna and the insect larvae Chironomus riparius. Inhibition strength was measured in vivo toward the cytochrome P450 catalysed conversion of 7-ethoxycoumarin to 7-hydroxycoumarin (ECOD). Synergistic potentials were determined as the ratio between predicted and observed toxicity of mixtures based on the model of concentration addition (CA) and independent action (IA). Azoles (n = 9-11) enhanced the toxicity of α-cypermethrin in D. magna (Synergy ratios CA: 0.8 - 16; IA: 1.1 - 22) and inhibited cytochrome P450 activity by different degrees (IC50: 0.0023 - 36 μM for D. magna and 0.08 - 24 μM for C. riparius). Inhibition strengths were strongly correlated in the two organisms (r: 0.937 p: 0.019 for triazoles and r: 0.903 p: 0.097 for imidazoles). Lipophilicity governed the inhibition strength of triazoles in both species (r > 0.9, p < 0.05). No correlation was observed between inhibition strengths and synergistic potentials. Several reasons for the apparent lack of correlation were discussed.

Drug-drug interactions in patients receiving hematopoietic stem cell transplantation

INTRODUCTION

Recipients of hematopoietic stem cell transplantation (HSCT) are exposed to numerous drugs in both pre- and post-transplantation period, which creates an opportunity for drug-drug interactions (DDIs); if clinically relevant DDIs happen, the risk of adverse treatment outcomes is increased. Areas covered: This review is focused on DDIs in recipients of HSCT that were observed and published as clinical trials, case series or case reports. Relevant publications were found by the systematic search of the following online databases: MEDLINE, SCOPUS, EBSCO, and SCINDEX. Expert opinion: The most important DDIs involve cytostatic or immunosuppressant drug on one side, and antimicrobial drugs on the other. The majority of clinically relevant interactions have pharmacokinetic character, involving drug metabolizing enzymes in the liver. Antifungal azoles inhibit metabolism of many cytostatic and immunosuppressant drugs at cytochromes and increase their plasma concentrations. Macrolide antibiotics and fluoroqunolones should be avoided in HSCT recipients, as they have much larger potential for DDIs than other antibiotic groups. HSCT recipients increasingly receive new immunomodulating drugs, and further observational studies are needed to reveal unsuspected DDIs with clinical relevance.

Sustained Impairment of Lurasidone Clearance After Discontinuation of Posaconazole: Impact of Obesity, and Implications for Patient Safety

PURPOSE/BACKGROUND

The antipsychotic agent lurasidone (Latuda®) is metabolized by Cytochrome P450-3A (CYP3A) enzymes. Coadministration with strong CYP3A inhibitors (such as ketoconazole, posaconazole, and ritonavir) is contraindicated due to the risk of sedation and movement disorders from high levels of lurasidone. This study evaluated the time-course of recovery from the posaconazole drug interaction, and the effect of obesity on the recovery process.

METHODS/PROCEDURES

Healthy normal-weight volunteers (n = 11, mean body mass index, BMI, = 23.1 kg/m) and otherwise healthy obese subjects (n = 13, mean BMI = 49.3 kg/m) received single doses of lurasidone in the baseline control condition, again during coadministration of posaconazole, and at 4 additional time points during the 2 weeks after posaconazole discontinuation.

FINDINGS/RESULTS

With posaconazole coadministration, lurasidone area under the concentration curve (AUC) increased by an arithmetic mean factor of 6.2 in normals, and by 4.9 in obese subjects. Post-treatment washout of posaconazole was slow in normals (mean half-life 31 hours), and further prolonged in obese subjects (53 hours). Recovery of lurasidone AUC toward baseline was correspondingly slow, and was incomplete. AUC remained significantly elevated above baseline both in normals (factor of 2.1) and obese subjects (factor of 3.4) even at 2 weeks after stopping posaconazole.

IMPLICATIONS/CONCLUSIONS

Product labeling does not address the necessary delay after discontinuation of a strong CYP3A inhibitor before lurasidone can be safely administered. We recommend requiring normal-weight and obese patients to limit the dosage of lurasidone, or undergo a washout period, for two and three weeks, respectively, after discontinuation of posaconazole.

Pharmacokinetic/pharmacodynamic drug-drug interactions of avatrombopag when coadministered with dual or selective CYP2C9 and CYP3A interacting drugs

AIMS

Avatrombopag, a thrombopoietin receptor agonist, is a substrate of cytochrome P450 (CYP) 2C9 and CYP3A. We assessed three drug-drug interactions of avatrombopag as a victim with dual or selective CYP2C9/3A inhibitors and inducers.

METHODS

This was a three-part, open-label study. Forty-eight healthy subjects received single 20 mg doses of avatrombopag alone or with one of 3 CYP2C9/3A inhibitors or inducers: fluconazole 400 mg once daily for 16 days, itraconazole 200 mg twice daily on Day 1 and 200 mg once daily on Days 2-16, or rifampicin 600 mg once daily for 16 days. Pharmacokinetics, pharmacodynamics (platelet count) and safety of avatrombopag were evaluated.

RESULTS

Coadministration of a single 20-mg dose of avatrombopag with fluconazole at steady-state resulted in 2.16-fold increase of AUC of avatrombopag, prolonged terminal elimination phase half-life (from 19.7 h to 39.9 h) and led to a clinically significant increase in maximum platelet count (1.66-fold). Itraconazole had a mild increase on both avatrombopag pharmacokinetics and pharmacodynamics compared to fluconazole. Coadministration of rifampicin caused a 0.5-fold decrease in AUC and shortened terminal elimination phase half-life (from 20.3 h to 9.84 h), but has no impact on maximum platelet count. Coadministration with interacting drugs was found to be generally safe and well-tolerated.

CONCLUSIONS

The results from coadministration of fluconazole or itraconazole suggest that CYP2C9 plays a more predominant role in metabolic clearance of avatrombopag than CYP3A. To achieve comparable platelet count increases when avatrombopag is coadministered with CYP3A and CYP2C9 inhibitors, an adjustment in the dose or duration of treatment is recommended, while coadministration with strong inducers is not currently recommended.