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Transmembrane drug transporters can be important determinants of the pharmacokinetics, efficacy, and safety profiles of drugs. To investigate the potential cooperative and/or counteracting interplay of OATP1A/1B/2B1 uptake transporters and ABCB1 and ABCG2 efflux transporters in physiology and pharmacology, we generated a new mouse model (Bab12), deficient for Slco1a/1b, Slco2b1, Abcb1a/1b and Abcg2. Bab12 mice were viable and fertile. We compared wild-type, Slco1a/1b/2b1 -/- , Abcb1a/1b;Abcg2 -/- and Bab12 strains. Endogenous plasma conjugated bilirubin levels ranked as follows: wild-type = Abcb1a/1b;Abcg2 -/- << Slco1a/1b/2b1 -/- < Bab12 mice. Plasma levels of rosuvastatin and fexofenadine were elevated in Slco1a/1b/2b1 -/- and Abcb1a/1b;Abcg2 -/- mice compared to wild-type, and dramatically increased in Bab12 mice. Although systemic exposure of larotrectinib and repotrectinib was substantially increased in the separate multidrug transporter knockout strains, no additive effects were observed in the combination Bab12 mice. Significantly higher plasma exposure of fluvastatin and pravastatin was only found in Slco1a/1b/2b1-deficient mice. However, noticeable transport by Slco1a/1b/2b1 and Abcb1a/1b and Abcg2 across the BBB was observed for fluvastatin and pravastatin, respectively, by comparing Bab12 mice with Abcb1a/1b;Abcg2 -/- or Slco1a/1b/2b1 -/- mice. Quite varying behavior in plasma exposure of erlotinib and its metabolites was observed among these strains. Bab12 mice revealed that Abcb1a/1b and/or Abcg2 can contribute to conjugated bilirubin elimination when Slco1a/1b/2b1 are absent. Our results suggest that the interplay of Slco1a/1b/2b1, Abcb1a/1b, and Abcg2 could markedly affect the pharmacokinetics of some, but not all drugs and metabolites. The Bab12 mouse model will represent a useful tool for optimizing drug development and clinical application, including efficacy and safety. [Display omitted] • Bab12 mice deficient for Slco1a/1b , Slco2b1 , Abcb1 and Abcg2 are viable and fertile. • Abcb1 and/or Abcg2 contribute to conjugated bilirubin elimination. • Slco1a/1b/2b1 mediates uptake of fluvastatin across the blood-brain barrier. • Interplay of uptake and efflux transporters substantially affects drug disposition. • Bab12 mice offer a valuable tool for optimising drug development and application. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The first bio-analytical assay for a combination of ALK inhibitors is presented. • The first assay for ALK inhibitors in tissue homogenates is reported. • The LC–MS/MS method has successfully been validated in six matrices. • The assay was applied for a pilot study of brigatinib in wild type mice. Abstract Several second and third generation ALK inhibitors have been introduced in recent years. A bioanalytical assay for simultaneous quantification of alectinib, brigatinib, and lorlatinib was developed and validated for human plasma. The method was also partially validated for diluted mouse plasma and tissue homogenates of brain, liver, kidney, and spleen. Samples (40 μl) were pretreated in a 96-well plate by protein precipitation with acetonitrile containing the internal standard [2H 8 ]-alectinib. After chromatographic separation on an ethylene bridged octadecyl silica column by gradient elution at 600 μl/min using 1% (v/v) formic acid (in water) and acetonitrile, compounds were ionized by a turbo electrospray and monitored by selected reaction monitoring on a triple quadrupole mass spectrometer. Validation was performed in a 2–2000 ng/ml concentration range for alectinib and lorlatinib and a 4–4000 ng/ml range for brigatinib. Precisions (within–day and between–day) were in the range 2.2–15.0% and accuracies were in between 87.2 and 110.2% for all matrices and levels. Compounds were sufficiently stable under most investigated conditions. Results of a pilot pharmacokinetic and tissue distribution study for brigatinib in mice are reported. Finally, successful incurred samples reanalysis of tissue homogenate samples containing brigatinib and lorlatinib is presented. Lorlatinib homogenate samples were also successfully reanalyzed using a second independent assay (cross-validation). [ABSTRACT FROM AUTHOR]

Highlights: [•] The first validated bioanalytical assay for rucaparib has been reported. [•] The assay has successfully been validated in the 1.25–2000ng/ml range. [•] The drug is sufficiently stable under all conditions relevant for the assay. [•] First pharmacokinetics in female wild-type FVB mice has reported. [ABSTRACT FROM AUTHOR]

Abstract: A quantitative assay for simultaneous measurement of individual human neutrophil peptide-1, -2 and -3 concentrations will aid in exploring the potential of these antimicrobial peptides as biomarkers for various diseases. Therefore, a liquid chromatography–tandem mass spectrometry method has been developed and validated to allow separate quantification of the three human neutrophil peptides in human plasma and serum. Plasma and serum samples (100μl) were deproteinized by precipitation, followed by chromatographic separation on a Symmetry 300 C18 column (50mm×2.1mm I.D., particle size 3.5μm), using a water–methanol gradient containing 0.25% (v/v) formic acid and human alpha-defensin 5 as internal standard. Tandem mass spectrometric detection was performed on a triple quadrupole mass spectrometer equipped with electrospray ionization. Despite low fragmentation efficiency of the antimicrobial peptides, multiple reaction monitoring was used for detection, though selecting the quaternary charged ions as both precursor and product. The method was linear for concentrations between 5 and 1000ng/ml with a limit of detection around 3ng/ml for all peptides. Intra- and inter-assay precisions were 14.8 and 19.1%, respectively, at the lowest measured endogenous concentration (6.4ng/ml of HNP-1 in plasma), representing the lower limit of quantification of the assay. Recoveries of HNP-1, -2 and -3 from plasma and serum ranged between 85 and 128%. Analysis of serum samples from intensive care patients showed average concentrations of 362, 570 and 143ng/ml for HNP-1, -2 and -3, respectively. [Copyright &y& Elsevier]