IL4I1 Is a Metabolic Immune Checkpoint that Activates the AHR and Promotes Tumor Progression.

Aryl hydrocarbon receptor (AHR) activation by tryptophan (Trp) catabolites enhances tumor malignancy and suppresses anti-tumor immunity. The context specificity of AHR target genes has so far impeded systematic investigation of AHR activity and its upstream enzymes across human cancers. A pan-tissue AHR signature, derived by natural language processing, revealed that across 32 tumor entities, interleukin-4-induced-1 (IL4I1) associates more frequently with AHR activity than IDO1 or TDO2, hitherto recognized as the main Trp-catabolic enzymes. IL4I1 activates the AHR through the generation of indole metabolites and kynurenic acid. It associates with reduced survival in glioma patients, promotes cancer cell motility, and suppresses adaptive immunity, thereby enhancing the progression of chronic lymphocytic leukemia (CLL) in mice. Immune checkpoint blockade (ICB) induces IDO1 and IL4I1. As IDO1 inhibitors do not block IL4I1, IL4I1 may explain the failure of clinical studies combining ICB with IDO1 inhibition. Taken together, IL4I1 blockade opens new avenues for cancer therapy.

Feasibility and Safety of Sildenafil to Repair Brain Injury Secondary to Birth Asphyxia (SANE-01): A Randomized, Double-blind, Placebo-controlled Phase Ib Clinical Trial.

OBJECTIVE: To test feasibility and safety of administering sildenafil in neonates with neonatal encephalopathy (NE), developing brain injury despite therapeutic hypothermia (TH). STUDY DESIGN: We performed a randomized, double-blind, placebo-controlled phase Ib clinical trial between 2016 and 2019 in neonates with moderate or severe NE, displaying brain injury on day-2 magnetic resonance imaging (MRI) despite TH. Neonates were randomized (2:1) to 7-day sildenafil or placebo (2 mg/kg/dose enterally every 12 hours, 14 doses). Outcomes included feasibility and safety (primary outcomes), pharmacokinetics (secondary), and day-30 neuroimaging and 18-month neurodevelopment assessments (exploratory). RESULTS: Of the 24 enrolled neonates, 8 were randomized to sildenafil and 3 to placebo. A mild decrease in blood pressure was reported in 2 of the 8 neonates after initial dose, but not with subsequent doses. Sildenafil plasma steady-state concentration was rapidly reached, but decreased after TH discontinuation. Twelve percent of neonates (1/8) neonates died in the sildenafil group and 0% (0/3) in the placebo group. Among surviving neonates, partial recovery of injury, fewer cystic lesions, and less brain volume loss on day-30 magnetic resonance imaging were noted in 71% (5/7) of the sildenafil group and in 0% (0/3) of the placebo group. The rate of death or survival to 18 months with severe neurodevelopmental impairment was 57% (4/7) in the sildenafil group and 100% (3/3) in the placebo group. CONCLUSIONS: Sildenafil was safe and well-absorbed in neonates with NE treated with TH. Optimal dosing needs to be established. Evaluation of a larger number of neonates through subsequent phases II and III trials is required to establish efficacy. CLINICAL TRIAL REGISTRATION: ClinicalTrials.govNCT02812433.

Therapeutic drug monitoring of osimertinib in non-small cell lung cancer and short bowel syndrome: A case report.

Short bowel syndrome (SBS) following extensive intestinal resection is often characterized by impaired absorption of orally administered drugs, including tyrosine kinase inhibitors (TKI). We report the case of a patient with EGFR-mutated non-small cell lung carcinoma treated with 80 mg/day of the TKI osimertinib who achieved partial response of the tumour, but was subsequently subjected to a double-barrelled jejunostomy due to ileus. Due to the development of SBS after the bypass surgery, plasma concentrations of osimertinib were monitored using mass spectrometry. The therapeutic drug monitoring confirmed a malabsorption of osimertinib in the patient (108 ng/mL, which is below the 5th percentile of the expected plasma concentration) and was useful to guide adjustments of TKI dosing in order to achieve adequate blood levels (161 ng/mL after increase of the dose to 120 mg/day) in order to maintain tumour control.

In vitro evaluation of the reductive carbonyl idarubicin metabolism to evaluate inhibitors of the formation of cardiotoxic idarubicinol via carbonyl and aldo-keto reductases.

The most important dose-limiting factor of the anthracycline idarubicin is the high risk of cardiotoxicity, in which the secondary alcohol metabolite idarubicinol plays an important role. It is not yet clear which enzymes are most important for the formation of idarubicinol and which inhibitors might be suitable to suppress this metabolic step and thus would be promising concomitant drugs to reduce idarubicin-associated cardiotoxicity. We, therefore, established and validated a mass spectrometry method for intracellular quantification of idarubicin and idarubicinol and investigated idarubicinol formation in different cell lines and its inhibition by known inhibitors of the aldo-keto reductases AKR1A1, AKR1B1, and AKR1C3 and the carbonyl reductases CBR1/3. The enzyme expression pattern differed among the cell lines with dominant expression of CBR1/3 in HEK293 and MCF-7 and very high expression of AKR1C3 in HepG2 cells. In HEK293 and MCF-7 cells, menadione was the most potent inhibitor (IC50 = 1.6 and 9.8 µM), while in HepG2 cells, ranirestat was most potent (IC50 = 0.4 µM), suggesting that ranirestat is not a selective AKR1B1 inhibitor, but also an AKR1C3 inhibitor. Over-expression of AKR1C3 verified the importance of AKR1C3 for idarubicinol formation and showed that ranirestat is also a potent inhibitor of this enzyme. Taken together, our study underlines the importance of AKR1C3 and CBR1 for the reduction of idarubicin and identifies potent inhibitors of metabolic formation of the cardiotoxic idarubicinol, which should now be tested in vivo to evaluate whether such combinations can increase the cardiac safety of idarubicin therapies while preserving its efficacy.

Extracellular Vesicles as Surrogates for the Regulation of the Drug Transporters ABCC2 (MRP2) and ABCG2 (BCRP).

Drug efflux transporters of the ATP-binding-cassette superfamily play a major role in the availability and concentration of drugs at their site of action. ABCC2 (MRP2) and ABCG2 (BCRP) are among the most important drug transporters that determine the pharmacokinetics of many drugs and whose overexpression is associated with cancer chemoresistance. ABCC2 and ABCG2 expression is frequently altered during treatment, thus influencing efficacy and toxicity. Currently, there are no routine approaches available to closely monitor transporter expression. Here, we developed and validated a UPLC-MS/MS method to quantify ABCC2 and ABCG2 in extracellular vesicles (EVs) from cell culture and plasma. In this way, an association between ABCC2 protein levels and transporter activity in HepG2 cells treated with rifampicin and hypericin and their derived EVs was observed. Although ABCG2 was detected in MCF7 cell-derived EVs, the transporter levels in the vesicles did not reflect the expression in the cells. An analysis of plasma EVs from healthy volunteers confirmed, for the first time at the protein level, the presence of both transporters in more than half of the samples. Our findings support the potential of analyzing ABC transporters, and especially ABCC2, in EVs to estimate the transporter expression in HepG2 cells.

Influence of a Short Course of Ritonavir Used as Booster in Antiviral Therapies Against SARS-CoV-2 on the Exposure of Atorvastatin and Rosuvastatin.

PURPOSE: Early antiviral treatment with nirmatrelvir/ritonavir is recommended for SARS-CoV-2-infected patients at high risk for severe courses. Such patients are usually chronically ill and susceptible to adverse drug interactions caused by ritonavir. We investigated the interactions of short-term low-dose ritonavir therapy with atorvastatin and rosuvastatin, two statins commonly used in this population. METHOD: We assessed exposure changes (area under the concentration-time curve (AUC∞) and maximum concentration (Cmax)) of a single dose of 10 mg atorvastatin and 10 mg rosuvastatin before and on the fifth day of ritonavir treatment (2 × 100 mg/day) in healthy volunteers and developed a semi-mechanistic pharmacokinetic model to estimate dose adjustment of atorvastatin during ritonavir treatment. RESULTS: By the fifth day of ritonavir treatment, the AUC∞ of atorvastatin increased 4.76-fold and Cmax 3.78-fold, and concurrently, the concentration of atorvastatin metabolites decreased to values below the lower limit of quantification. Pharmacokinetic modelling indicated that a stepwise reduction in atorvastatin dose during ritonavir treatment with a stepwise increase up to 4 days after ritonavir discontinuation can keep atorvastatin exposure within safe and effective margins. Rosuvastatin pharmacokinetics were only mildly modified; ritonavir significantly increased the Cmax 1.94-fold, while AUC∞ was unchanged. CONCLUSION: Atorvastatin doses should likely be adjusted during nirmatrelvir/ritonavir treatment. For patients on a 20-mg dose, we recommend half of the original dose. In patients taking 40 mg or more, a quarter of the dose should be taken until 2 days after discontinuation of nirmatrelvir/ritonavir. Patients receiving rosuvastatin do not need to change their treatment regimen. TRIAL REGISTRATION: EudraCT number: 2021-006634-39. DRKS00027838.

Effect of Clomethiazole Vs. Clorazepate on Hepatic Fat and Serum Transaminase Activities in Alcohol-Associated Liver Disease: Results from a Randomized, Controlled Phase II Clinical Trial.

AIMS: Alcohol-associated liver disease (ALD) is a global health problem caused, among other factors, by oxidative stress from the formation of reactive oxygen species (ROS). One important source of ROS is microsomal ethanol metabolism catalyzed by cytochrome P450 2E1 (CYP2E1), which is induced by chronic ethanol consumption. Inhibition of CYP2E1 by clomethiazole (CMZ) decreases oxidative stress in cell cultures and improves ALD in animal studies. Our study aimed to assess the benefits of a CYP2E1 inhibitor (clomethiazole) in detoxification of patients with ALD. METHODS: Open label, randomized controlled clinical trial to study whether CYP2E1 inhibition improves ALD in the patients with alcohol use disorders admitted for alcohol detoxification therapy (ADT). Patients had to have a serum aspartate aminotransferase (AST) activity exceeding twice the upper normal limit at time of admission and be non-cirrhotic defined by fibroscan value <12 kPa. Sixty patients were randomly assigned to ADT with either CMZ or clorazepate (CZP) for 7-10 days in a 1:1 ratio. The chlorzoxazone test of CYP2E1 activity was performed at enrolment and at 2 points during the study. RESULTS: ADT improved hepatic steatosis (controlled attenuation parameter) in both groups significantly. A trend towards a greater improvement in hepatic fat content during ADT (-21.5%) was observed in the CMZ group (252 ± 48 dB/m vs. 321 ± 38 dB/m; P < 0.0001) compared with the CZP group (-13.9%; 273 ± 38 dB/m vs. 317 ± 39 dB/m; P < 0.0001). As already reported, serum AST (P < 0.004) and alanine aminotransferase (ALT) activities (P < 0.0006) significantly decreased in CMZ patients as compared with patients on CZP by the end of hospitalization. A significant correlation was found between AST (P = 0.023), ALT (P = 0.009), GGT (P = 0.039) and CAP. CONCLUSION: This study demonstrates that CMZ improves clinical biomarkers for ALD in humans most likely due to its inhibitory effect on CYP2E1. Because of its addictive potential, CMZ can only be given for a short period of time and therefore other CYP2E1 inhibitors to treat ALD are needed.

Desorption Kinetics Evaluation for the Development of Validated Desorption Electrospray Ionization-Mass Spectrometric Assays for Drug Quantification in Tissue Sections.

The development of desorption/ionization (DI) mass spectrometric (MS) assays for drug quantification in tissue sections and their validation according to regulatory guidelines would enable their universalization for applications in (clinical) pharmacology. Recently, new enhancements in desorption electrospray ionization (DESI) have highlighted the reliability of this ion source for the development of targeted quantification methods that meet requirements for method validation. However, it is necessary to consider subtle parameters leading to the success of such method developments, such as the morphology of desorption spots, the analytical time, and sample surface, to cite but a few. Here, we provide additional experimental data highlighting an additional important parameter, based on the unique advantage of DESI-MS on continuous extraction during analysis. We demonstrate that considering desorption kinetics during DESI analyses would largely help (i) reducing analytical time during profiling analyses, (ii) verifying solvent-based drug extraction using the selected sample preparation method for profiling and imaging modes, and (iii) predicting the feasibility of imaging assays using samples in a given expected concentration range of the targeted drug. These observations will likely serve as precious guidance for the development of validated DESI-profiling and imaging methods in the future.

Correction: Bay et al. Functional Characterization of the Solute Carrier LAT-1 (SLC7A5/SLC3A2) in Human Brain Capillary Endothelial Cells with Rapid UPLC-MS/MS Quantification of Intracellular Isotopically Labelled L-Leucine. Int. J. Mol. Sci. 2022, 23, 3637.

The authors would like to make the following corrections to the publication [...].

Evaluation of CYP2C19 activity using microdosed oral omeprazole in humans.

PURPOSE: To investigate the suitability of microdosed oral omeprazole for predicting CYP2C19 activity in vivo in combination with simultaneous assessment of CYP3A and CYP2D6 activity using both microdosed midazolam and yohimbine. METHODS: An open, fixed-sequence study was carried out in 20 healthy participants. Single microdosed (100 µg) and therapeutic (20 mg) doses of omeprazole were evaluated without comedication and after administration of established CYP2C19 perpetrators fluconazole (inhibition) and rifampicin (induction). To prevent degradation of the uncoated omeprazole microdose, sodium bicarbonate buffer was administered. The pharmacokinetics of omeprazole and its 5-hydroxy-metabolite were assessed as well as the pharmacokinetics of midazolam and yohimbine to estimate CYP3A4 and CYP2D6 activity. RESULTS: Calculated pharmacokinetic parameters after administration of 100 µg and 20 mg omeprazole in healthy subjects suggest dose proportionality. Omeprazole clearance was significantly decreased by fluconazole from 388 [95% CI: 266-565] to 47.2 [42.8-52.0] mL/min after 20 mg omeprazole and even further after 100 µg omeprazole (29.4 [24.5-35.1] mL/min). Rifampicin increased CYP2C19-mediated omeprazole metabolism. The omeprazole hydroxylation index was significantly related to omeprazole clearance for both doses. Both fluconazole and rifampicin altered CYP3A4 activity whereas no change of CYP2D6 activity was observed at all. CONCLUSIONS: Microdosed oral omeprazole is suitable to determine CYP2C19 activity, also during enzyme inhibition and induction. However, the administration of sodium bicarbonate buffer also had a small influence on all victim drugs used. TRIAL REGISTRATION: EudraCT: 2017-004270-34.

Functional Characterization of the Solute Carrier LAT-1 (SLC7A5/SLC2A3) in Human Brain Capillary Endothelial Cells with Rapid UPLC-MS/MS Quantification of Intracellular Isotopically Labelled L-Leucine.

The solute carrier L-type amino acid transporter 1 (LAT-1/SLC7A5) is a viable target for drug delivery to the central nervous system (CNS) and tumors due to its high abundance at the blood-brain barrier and in tumor tissue. LAT-1 is only localized on the cell surface as a heterodimer with CD98, which is not required for transporter function. To support future CNS drug-delivery development based on LAT-1 targeting, we established an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) assay for stable isotopically labeled leucine ([13C6, 15N]-L-leucine), with a dynamic range of 0.1-1000 ng/mL that can be applied for the functional testing of LAT-1 activity when combined with specific inhibitors and, consequently, the LAT-1 inhibition capacity of new compounds. The assay was established in a 96-well format, facilitating high-throughput experiments, and, hence, can support the screening for novel inhibitors. Applicable recommendations of the US Food and Drug Administration and European Medicines Agency for bioanalytical method validation were followed to validate the assay. The assay was applied to investigate the IC50 of two well-known LAT-1 inhibitors on hCMEC/D3 cells: the highly specific LAT-1 inhibitor JPH203, which was also used to demonstrate LAT-1 specific uptake, and the general system L inhibitor BCH. In addition, the [13C6, 15N]-L-leucine uptake was determined on two human brain capillary endothelial cell lines (NKIM-6 and hCMEC/D3), which were characterized for their expressional differences of LAT-1 at the protein and mRNA level and the surface amount of CD98. The IC50 values of the inhibitors were in concordance with previously reported values. Furthermore, the [13C6, 15N]-L-leucine uptake was significantly higher in hCMEC/D3 cells compared to NKIM-6 cells, which correlated with higher expression of LAT-1 and a higher surface amount of CD98. Therefore, the UPLC-MS/MS quantification of ([13C6, 15N]-L-leucine is a feasible strategy for the functional characterization of LAT-1 activity in cells or tissue.

Metabolic Effect of Blocking Sodium-Taurocholate Co-Transporting Polypeptide in Hypercholesterolemic Humans with a Twelve-Week Course of Bulevirtide-An Exploratory Phase I Clinical Trial.

Bile acids (BA) play an important role in cholesterol metabolism and possess further beneficial metabolic effects as signalling molecules. Blocking the hepatocellular uptake of BA via sodium-taurocholate co-transporting polypeptide (NTCP) with the first-in-class drug bulevirtide, we expected to observe a decrease in plasma LDL cholesterol. In this exploratory phase I clinical trial, volunteers with LDL cholesterol > 130 mg/dL but without overt atherosclerotic disease were included. Thirteen participants received bulevirtide 5 mg/d subcutaneously for 12 weeks. The primary aim was to estimate the change in LDL cholesterol after 12 weeks. Secondary endpoints included changes in total cholesterol, HDL cholesterol, lipoprotein(a), inflammatory biomarkers, and glucose after 12 weeks. In addition, cardiac magnetic resonance imaging (CMR) was performed at four time points. BA were measured as biomarkers of the inhibition of hepatocellular uptake. After 12 weeks, LDL cholesterol decreased not statistically significantly by 19.6 mg/dL [−41.8; 2.85] (Hodges−Lehmann estimator with 95% confidence interval). HDL cholesterol showed a significant increase by 5.5 mg/dL [1.00; 10.50]. Lipoprotein(a) decreased by 1.87 mg/dL [−7.65; 0]. Inflammatory biomarkers, glucose, and cardiac function were unchanged. Pre-dose total BA increased nearly five-fold (from 2026 nmol/L ± 2158 (mean ± SD) at baseline to 9922 nmol/L ± 7357 after 12 weeks of treatment). Bulevirtide was generally well tolerated, with most adverse events being administration site reactions. The exploratory nature of the trial with a limited number of participants allows the estimation of potential effects, which are crucial for future pharmacological research on bile acid metabolism in humans.

Important Requirements for the Selection of Internal Standards during the Development of Desorption/Ionization Assays for Drug Quantification in Biological Matrices-A Practical Example.

Desorption/ionization mass spectrometry (DI-MS) approaches allow for the rapid quantification of drugs in biological matrices using assays that can be validated according to regulatory guidelines. However, specific adaptations must be applied to create reliable quantification methods, depending on the approach and instrumentation used. In the present article, we demonstrate the importance of the molecular weight, the fragmentation pattern, and the purity of the internal standard for the development of matrix-assisted laser desorption/ionization (MALDI)-ion mobility (IM)-tandem MS and MS/MS methods. We present preliminary results of method development for the quantification of selinexor in microdialysis fluids with a stable isotopically labeled internal standard. In addition, we discuss the selection of internal standards for MALDI-MS assays using different instrumentations.

Desorption/Ionization-MS Methods for Drug Quantification in Biological Matrices and Their Validation Following Regulatory Guidance.

Desorption/ionization (DI) methods play an important role among the panel of mass spectrometric (MS) approaches for the rapid and sensitive quantification of drugs from the surface of solid samples. The possibility to implement these approaches for pharmacokinetic/pharmacodynamic investigations in early phase clinical trials depends on the ability to validate quantification assays according to regulatory guidelines (e.g., US Food and Drug Administration and European Medicines Agency) for bioanalytical method validation. However, these guidelines were designed for the validation of liquid chromatography-MS (LC-MS) methods and ligand binding assays. To apply the validation parameters to DI-MS methods (also referred here as on-surface MS) for drug quantification, it is important to consider the particularities of DI approaches compared to LC-MS methods. In this Perspective, we summarize the various applications of on-surface MS methods for drug quantification with their advantages over other MS methods, and provide our point of view regarding future proper method development and validation.

Approaching sites of action of drugs in clinical pharmacology: New analytical options and their challenges.

Clinical pharmacology is an important discipline for drug development aiming to define pharmacokinetics (PK), pharmacodynamics (PD) and optimum exposure to drugs, i.e. the concentration-response relationship and its modulators. For this purpose, information on drug concentrations at the anatomical, cellular and molecular sites of action is particularly valuable. In pharmacological assays, the limited accessibility of target cells in readily available samples (i.e. blood) often hampers mass spectrometry-based monitoring of the absolute quantity of a compound and the determination of its molecular action at the cellular level. Recently, new sample collection methods have been developed for the specific capture of rare circulating cells, especially for the diagnosis of circulating tumour cells. In parallel, new advances and developments in mass spectrometric instrumentation now allow analyses to be scaled down to the cellular level. Together, these developments may permit the monitoring of minute drug quantities and show their effect at the cellular level. In turn, such PK/PD associations on a cellular level would not only enrich our pharmacological knowledge of a given compound but also expand the basis for PK/PD simulations. In this review, we describe novel concepts supporting clinical pharmacology at the anatomical, cellular and molecular sites of action, and highlight the new challenges in mass spectrometry-based monitoring. Moreover, we present methods to tackle these challenges and define future needs.

Intact plasma quantification of the large therapeutic lipopeptide bulevirtide.

Bulevirtide is a first-in-class entry inhibitor of the hepatitis B and hepatitis delta virus blocking the sodium/bile acid co-transporter NTCP, and was recently approved for the treatment of hepatitis D as a priority medicine (prime) in an accelerated assessment by the European Medicines Agency. It is a very large lipopeptide comprising 47 amino acids in its sequence and a myristoylation at the N-terminus. For support of clinical development, we established highly sensitive plasma quantification assays using 100 µL of plasma, spanning concentrations of 0.1 to 100 ng/mL and 1 to 1000 ng/mL with the option to measure ten-fold diluted samples up to 10,000 ng/mL. Quantification was performed with UPLC-MS/MS measurements after extraction with protein precipitation. Both assays were fully validated according to the pertinent guidelines of the FDA and EMA, including incurred sample reanalyses and cross-validation using clinical study samples. Graphical abstract.

Rapid MALDI-MS Assays for Drug Quantification in Biological Matrices: Lessons Learned, New Developments, and Future Perspectives.

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) has rarely been used in the field of therapeutic drug monitoring, partly because of the complexity of the ionization processes between the compounds to be quantified and the many MALDI matrices available. The development of a viable MALDI-MS method that meets regulatory guidelines for bioanalytical method validation requires prior knowledge of the suitability of (i) the MALDI matrix with the analyte class and properties for ionization, (ii) the crystallization properties of the MALDI matrix with automation features, and (iii) the MS instrumentation used to achieve sensitive and specific measurements in order to determine low pharmacological drug concentrations in biological matrices. In the present hybrid article/white paper, we review the developments required for the establishment of MALDI-MS assays for the quantification of drugs in tissues and plasma, illustrated with concrete results for the different steps. We summarize the necessary parameters that need to be controlled for the successful development of fully validated MALDI-MS methods according to regulatory authorities, as well as currently unsolved problems and promising ways to address them. Finally, we propose an expert opinion on future perspectives and needs in order to establish MALDI-MS as a universal method for therapeutic drug monitoring.

Application of a microdosed cocktail of 3 oral factor Xa inhibitors to study drug-drug interactions with different perpetrator drugs.

AIMS: Using 3 different perpetrators the impact of voriconazole, cobicistat and rifampicin (single dose), we evaluated the suitability of a microdose cocktail of factor Xa inhibitors (FXaI; rivaroxaban, apixaban and edoxaban; 100 µg in total) to study drug-drug interactions. METHODS: Three cohorts of 6 healthy volunteers received 2 treatments with microdoses of rivaroxaban, apixaban and edoxaban alone and with coadministration of 1 of the perpetrators. Plasma and urine concentrations of microdosed apixaban, edoxaban and rivaroxaban were quantified using a validated ultra-performance liquid chromatography-tandem mass spectrometry with a lower limit of quantification of 2.5 pg/mL. RESULTS: Voriconazole caused only a minor interaction with apixaban and rivaroxaban, none with edoxaban. Cobicistat significantly increased exposure of all 3 FXaI with area under the plasma concentration-time curve ratios of 1.67 (apixaban), 1.74 (edoxaban) and 2.0 (rivaroxaban). A single dose of rifampicin decreased the volume of distribution and elimination half-life of all 3 FXaI. CONCLUSIONS: The microdosed FXaI cocktail approach is able to generate drug interaction data and can help elucidating the mechanism involved in the clearance of the different victim drugs. This is a safe approach to concurrently study drug-drug interactions with a drug class. (EudraCT 2016-003024-23).

Rapid drug detection in whole blood droplets using a desorption electrospray ionization static profiling approach - a proof-of-concept.

RATIONALE: The introduction of desorption electrospray ionization (DESI) - and ambient desorption/ionization (ADI) ion sources in general - in the 2000s has opened new possibilities for mass spectrometric (MS) analyses of biological sample surfaces. DESI allows for a rapid screening of solid samples because no sample preparation is needed and the analysis is performed at atmospheric pressure. In the present study, we used DESI as an ion source for the rapid detection of a small molecule in blood droplets deposited on glass slides. METHODS: Blood was spiked with different concentrations of a model drug, mebendazole. One microliter blood droplets of each preparation were deposited on the surface of a glass slide and analyzed by DESI, either in imaging or profiling mode. RESULTS: The results suggested that DESI imaging mode was not appropriate for the detection of mebendazole in blood droplets as an initial solvation time was necessary before the obtention of signal. A profiling approach consisting of analyzing a single position of the blood droplet was used for further analysis and allowed mebendazole to be detected in the fg range and to monitor the volume of sample analyzed. CONCLUSIONS: The study suggests that profiling mode at a single position is adequate for DESI analyses in whole blood droplets. This proof-of-concept study illustrates the potential of DESI profiling as a possible alternative to liquid chromatography/MS analyses of whole blood, when analyses are needed within a restricted time. Rapid detection methods in blood at atmospheric pressure may find interesting applications in the fields of toxicology and pharmacology.

An Underestimated Factor: The Extent of Cross-Reactions Modifying APIs in Surface-Modified Liposomal Preparations Caused by Comprised Activated Lipids.

Despite the nowadays available plentitude of strategies to selectively introduce functional surface modification of liposomes, in preclinical research this process is still primarily performed after liposomal preparation utilizing comprised activated phospholipids with functionalized head groups. However, because these activated lipids are present during the liposomal preparation process, they can cross-react with incorporated drugs, especially the particularly often utilized active esters and maleimide groups. Macromolecular drugs, being composed of amino acids, are particularly prone to such cross-reactions due to their often multiple reactive functionalities such as amino and disulfide groups. To demonstrate this impact on the formulation in liposomal surface modification, we assessed the extent of cross-reaction during the liposomal preparation of two activated phospholipids with typically used head group functionalized phospholipids, with the two peptide drugs vancomycin and insulin comprising disulfide and amino functionalities. Both drugs revealed a considerable fraction of covalent modification (estimated 2 to 12%) generated during the liposome preparation process with comprised activated lipids. Modification of the active pharmaceutical ingredients (APIs) was determined by high-resolution mass spectrometric analysis. These findings clearly demonstrate the non-negligibility of potential cross reactions using the post preparation liposomal surface modification strategy in preclinical research.