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Prediction of lefamulin epithelial lining fluid penetration after intravenous and oral administration using Phase 1 data and population pharmacokinetics methods.

ABSTRACT: OBJECTIVES:Lefamulin is a semi-synthetic intravenous and oral pleuromutilin antibiotic with activity against pathogens commonly associated with community-acquired bacterial pneumonia. Using data from two Phase 1 studies, a population pharmacokinetics (PPK) model for lefamulin in plasma and epithelial lining fluid (ELF) was constructed. METHODS:Plasma pharmacokinetic (PK) data from a crossover, bioavailability, food-effect study and plasma and ELF PK data from a tissue penetration study in normal healthy volunteers were used to construct a PPK model for lefamulin. Model development involved refinement of a previous PPK model for intravenous and oral administration, followed by application of the model to plasma and ELF data from the tissue penetration study. The ELF penetration ratio of lefamulin was determined using model-based simulations. RESULTS:The PPK analysis data set contained 1103 plasma and 12 ELF lefamulin concentrations from 32 subjects. A three-compartment model with non-linear protein binding and two parallel absorption processes provided precise and unbiased estimated plasma concentration-time profiles. The absorption rate was slower and bioavailability was decreased after a high-fat/high-calorie meal. ELF data were well described using first-order rate constants into and out of the ELF compartment. The median predicted lefamulin total-drug ELF AUC0-24/free-drug plasma AUC0-24 ratio was ?5:1 after intravenous or oral administration. CONCLUSIONS:The final PPK model allowed precise characterization of plasma and ELF exposures after intravenous and oral administration. The high ELF penetration ratio suggests that the penetration of lefamulin into the effect site is rapid and extensive, irrespective of route of administration.

SUBMITTER: Zhang L

PROVIDER: S-EPMC6449575 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature

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Project description:BackgroundThe nasal mucosa, as a primary site of entry for inhaled substances, contains both inhaled xenobiotic and endogenous biomarkers. Nasal mucosa can be non-invasively sampled (nasal epithelial lining fluid "NELF") and analyzed for biological mediators. However, methods for untargeted analysis of compounds inhaled and/or retained in the nasal mucosa are needed.ObjectivesThis study aimed to develop a high resolution LC-MS untargeted method to analyze collected NELF. Profiling of compounds in NELF samples will also provide baseline data for future comparative studies to reference.MethodsExtracted NELF analytes were injected to LC-ESI-MS. After spectrum processing, an in-house library provided annotations with high confidence, while more tentative annotation proposals were obtained via ChemSpider database matching.ResultsThe established method successfully detected unique molecular signatures within NELF. Baseline profiling of 27 samples detected 2002 unknown molecules, with 77 and 463 proposed structures by our in-house library and Chemspider matching. High confidence annotations revealed common metabolites and tentative annotations implied various environmental exposure biomarkers are also present in NELF.SignificanceThe experimental pipeline for analyzing NELF samples serves as simple and robust method applicable for future studies to characterize identities/effects of inhaled substances and metabolites retained in the nasal mucosa.Impact statementThe nasal mucosa contains exogenous and endogenous compounds. The development of an untargeted analysis is necessary to characterize the nasal exposome by deciphering the identity and influence of inhaled compounds on nasal mucosal biology. This study established a high resolution LC-MS based untargeted analysis of non-invasively collected nasal epithelial lining fluid. Baseline profiling of the nasal mucosa (n = 27) suggests the presence of environmental pollutants, along with detection of endogenous metabolites. Our results show high potential for the analytical pipeline to facilitate future respiratory health studies involving inhaled pollutants or pharmaceutical compounds and their effects on respiratory biology.

Project description:BackgroundIn 4 decades, numerous nicotine replacement therapy products have been developed. Population pharmacokinetic models can support exposure-response modeling and inform nicotine replacement therapy product development, but only limited model-based cross-study population pharmacokinetic analyses for nicotine replacement therapy products have been published.ObjectivesThe aim of this retrospective analysis was to assess the population pharmacokinetics of nicotine across intravenous, oral, transdermal and oromucosal (mouth spray, chewing gum, lozenge and inhaler) routes and formulations in healthy smoking subjects.MethodsData on 930 unique subjects (46,016 observations) from 29 single- and repeated-dose studies with multiple formulations across intravenous, oral, transdermal and oromucosal routes of administration were included. Data from intravenous and extravascular routes of administration were modelled separately for run efficiency reasons. For developing extravascular models, clearance and disposition parameters and their inter-individual variabilities were fixed to the estimates for intravenously delivered nicotine. Detectable pre-dose nicotine concentrations were modelled as a hypothetical nicotine bolus into the central compartment at the start of wash-out. Modelling repeated-dose oral and buccal administrations required a time-dependent increase in clearance or decrease in bioavailability to describe the data adequately.ResultsDisposition of intravenous nicotine was best described by a three-compartment model with initial and terminal half-lives of 7 min and 4.5 h, respectively, and the absorption of single oral doses was best described with a first-order absorption rate constant of 1.55 h-1. The data of buccal formulations were modelled with parallel oromucosal absorption and gastrointestinal absorption of a part of the dose that is swallowed. For transdermal nicotine, parallel zero- and first-order release from the patch and a transit-compartment absorption model best described the data. Key pharmacokinetic parameters were reliably estimated, with typical values for clearance (67 L/h for a 70-kg subject), volume of distribution (4.3 L/kg), oral bioavailability (40%) and transdermal bioavailability (76%) within expected ranges. The estimated fraction of the dose swallowed for buccal formulations ranged from 55% (gum) to 69% (lozenge).ConclusionsRobust population pharmacokinetic models were developed for five nicotine replacement therapy product types and for intravenous and oral nicotine. These population pharmacokinetic models are used in exposure-response analyses and simulation-based nicotine replacement therapy product design.

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Prediction of lefamulin epithelial lining fluid penetration after intravenous and oral administration using Phase 1 data and population pharmacokinetics methods.

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