Fluoroalkoholid LC-ESI-MS eluendi komponendina: kasutatavus ja rakendused

Väitekirja elektrooniline versioon ei sisalda publikatsioone.Ravimite kui peamiselt aluseliste ühendite pöördfaasvedelikkromatograafilised määramismetoodikad on seni kasutanud elueerimist eluendi madalal pH-l, kus analüüdid on protoneeritud ning seetõttu polaarsemad ja omavad viletsat retentsiooni. Analüütide määramiseks pöördfaaskromatograafias kasutatakse laialdaselt massispektromeetrilist detektorit, mis omakorda seab kasutatavatele eluentidele lenduvuse nõude. Aluseliste analüütide retentsiooni parandamiseks vedelikkromatograafilisel-massispektromeetrilisel (LC-MS) analüüsil tuleks kasutada kõrgemat puhverlahuse pH-d. Lenduvate aluseliste puhverlahuste valiku, mis on hetkel üsna piiratud, laiendamiseks uuriti fluoroalkohole - 1,1,1,3,3,3-heksfluoro-2-propanool (pKa=9.3) ja 1,1,1,3,3,3-heksafluoro-2-metüül-2-propanool (pKa=9.6) kasutusvõimalusi LC-MS aluseliste puhverlahustena. Töö tulemusena kirjeldati fluoroalkoholide kasutamisel pöördfaaskromatograafia retentsioonimehhanisme, fluoroalkoholide mõju analüütide ionisatsioonile, võrreldi mõju analüütide retentsioonile kasutades fluoroalkohole ning fluoreeritud statsionaarset faasi ning esitati fluoroalkoholide kasutamise eelised. Võrreldes tavapäraste puhverlahustega pakuvad fluoroalkoholid puhverlahustena analüütidele alternatiivseid retentsioonimehhanisme, mis parandab analüütide kromatograafilist lahutust. Töö käigus demonstreeriti fluoroalkoholide kasutamise edukaid rakendusnäiteid ravimite analüüsil keskkonnaproovidest ning inimese kehavedelikest.Reversed phase chromatographyc methods for analysis of pharmaceuticals (as mainly basic compounds) have used acidic conditions where analytes are predominantly on their protonated (hydrophilic) form and therefore have poor retention on stationary phase. Basic conditions for the analysis of basic compounds is more suitable. For detection, often mass spectrometry is used where volatile buffer solutions are required. Selection of volatile basic buffer compounds is limited for liquid chromatography-mass spectrometry (LC-MS) and therefore enhancements in the selection is more than welcomed. Two fluoroalcohols - 1,1,1,3,3,3-hexafluoro-2-propanol (pKa=9.3) and 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol (pKa=9.6) have been studied and evaluated in usage as LC-MS basic buffer components. As a result of present work the retention mechanisms provided by fluoroalcohols have described, the influence of fluoroalcohols for the ionization of analytes have been described, comparison with retention in fluorinated stationary phase have been demonstrated and advantages for usage of fluorinated alcohols as LC-MS buffer components have been demonstrated. Comparing with known buffer components fluoroalcohols provide alternative retention mechanisms and therefore the chromatographic separation can be enhanced. Successful application of usage of fluorinated alcohols have been demonstrated for analysis of pharmaceuticals in environmental samples and human blood plasma and urine samples

Scaling beta-lactam antimicrobial pharmacokinetics from early life to old age

AIMS Beta-lactam dose optimization in critical care is a current priority. We aimed to review the pharmacokinetics (PK) of three commonly used beta-lactams (amoxicillin ± clavulanate, piperacillin-tazobactam and meropenem) to compare PK parameters reported in critically and noncritically ill neonates, children and adults, and to investigate whether allometric and maturation scaling principles could be applied to describe changes in PK parameters through life. METHODS A systematic review of PK studies of the three drugs was undertaken using MEDLINE and EMBASE. PK parameters and summary statistics were extracted and scaled using allometric principles to 70 kg individual for comparison. Pooled data were used to model clearance maturation and decline using a sigmoidal (Hill) function. RESULTS A total of 130 papers were identified. Age ranged from 29 weeks to 82 years and weight from 0.9-200 kg. PK parameters from critically ill populations were reported with wider confidence intervals than those in healthy volunteers, indicating greater PK variability in critical illness. The standard allometric size and sigmoidal maturation model adequately described increasing clearance in neonates, and a sigmoidal model was also used to describe decline in older age. Adult weight-adjusted clearance was achieved at approximately 2 years postmenstrual age. Changes in volume of distribution were well described by the standard allometric model, although amoxicillin data suggested a relatively higher volume of distribution in neonates. CONCLUSIONS Critical illness is associated with greater PK variability than in healthy volunteers. The maturation models presented will be useful for optimizing beta-lactam dosing, although a prospective, age-inclusive study is warranted for external validation

ACUMEN: Amplifying Control and Understanding of Multiple ENtities

In virtual environments, the control of numerous entities in multiple dimensions can be difficult and tedious. In this paper, we present a system for synthesizing and recognizing aggregate movements in a virtual environment with a high-level (natural language) interface. The principal com- ponents include: an interactive interface for aggregate con- trol based on a collection of parameters extending an exist- ing movement quality model, a feature analysis of aggregate motion verbs, recognizers to detect occurrences of features in a collection of simulated entities, and a clustering algorithm that determines subgroups. Results based on simulations and a sample instruction application are shown

Ampitsilliini farmakokineetika enneaegsetel ja ajalistel vastsündinutel esimesel elunädalal

Eesti Arst 2022; 101(2):12

Mimicking in-vivo exposures to drug combinations in-vitro : anti-tuberculosis drugs in lung lesions and the hollow fiber model of infection

This research was supported by a British Society of Antimicrobial Chemotherapy Grant (GA2015-172R). FK has conducted the research as part of a Medical Research Council fellowship (MR/P014534/1) and consumables to develop the ultra-high-performance liquid chromatographic-tandem mass spectrometric detection method and analyse the samples were paid to Analytical Services International Ltd. from a Medical Research Council fellowship (MR/P014534/1).Here, we evaluate protocol requirements to mimic therapeutically relevant drug concentrations at the site of infection (i.e. lung lesion) in an in-vitro hollow fibre model of infection using pulmonary tuberculosis as a paradigm. Steady-state pharmacokinetic profiles in plasma, lung tissue and lung lesion homogenate were simulated for isoniazid, rifampicin and pyrazinamide and moxifloxacin. An R-shiny User Interface was developed to support conversion of in-vivo pharmacokinetic CMAX, TMAX and T1/2 estimates into pump settings. A monotherapy protocol mimicking isoniazid in lung lesion homogenate (isoniazid CMAX = 1,200 ng/ml, TMAX = 2.2 hr and T1/2 = 4.7 hr), and two combination therapy protocols including drugs with similar (isoniazid and rifampicin (CMAX = 400 ng/ml)) and different half-lives (isoniazid and pyrazinamide (CMAX = 28,900 ng/ml and T1/2 = 8.0 hr)) were implemented in a hollow-fiber system. Drug levels in the perfusate were analysed using ultra-high-performance liquid chromatographic-tandem mass spectrometric detection. Steady state pharmacokinetic profiles measured in the hollow fiber model were similar to the predicted in-vivo steady-state lung lesion homogenate pharmacokinetic profiles. The presented approach offers the possibility to use pharmacological data to study the effect of target tissue exposure for drug combinations. Integration with pharmacokinetics modelling principles through a web interface will provide access to a wider community interested in the evaluation of efficacy of anti-tubercular drugs.Publisher PDFPeer reviewe

Accumulation of sulfonamides and fluoroquinolones from soil to plants

Saabunud / Received 12.12.2022 ; Aktsepteeritud / Accepted 29.06.2023 ; Avaldatud veebis / Published online 15.08.2023 ; Vastutav autor / Corresponding author Merike Lillenberg ; [email protected] current study was conducted to determine the potential for some antibiotics to be taken up by food plants from soil fertilized with manure, sewage sludge or its compost containing antibiotic residues. The plants (potato – Solanum tuberosum L., carrot – Daucus carota L., and wheat – Triticum aestivum L.) were cultivated in greenhouse under natural light conditions in the presence of three fluoroquinolones (ciprofloxacin, ofloxacin, and norfloxacin), and two sulfonamides (sulfadimethoxine and sulfamethoxazole). The uptake of antibiotics was demonstrated from two different soils (loamy and loamy sand). The concentrations of each antibiotic in soil were 0.01, 0.1, 0.5, 1.0, and 10 mg kg–1. The antibiotics were extracted from the plants using the liquid extraction (LE) and cleaned up by the solid phase extraction (SPE). The extracts were analyzed by liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). The accumulation range depended on antibiotic con- centration in soil, chemical properties of the antibiotic, soil type, plant species and parts (overground or below-ground). At soil concentrations of 10 mg kg–1 antibiotics accumulated in edible parts of most plants in amounts, which exceeded their maximum residue levels (MRL) set for food of animal origin – 100 μg kg–1. The highest average content of antibiotics was detected in potato tubers and carrot roots grown in the loamy sand soil – 3897 μg kg–1 and 3400 μg kg–1 sulfamethoxazole. Plants accumulated antibiotics (ciprofloxacin and ofloxacin) from soil even at soil concentration of 0.01 mg kg–1. Mostly the highest concentrations of antibiotics were detected in below-ground parts of the plants grown in the loamy-sand soil

The Neonatal and Paediatric Pharmacokinetics of Antimicrobials study (NAPPA): investigating amoxicillin, benzylpenicillin, flucloxacillin and piperacillin pharmacokinetics from birth to adolescence

Background: Pharmacokinetic (PK) data underlying paediatric penicillin dosing remain limited, especially in critical care.// Objectives: The primary objective of the Neonatal and Paediatric Pharmacokinetics of Antimicrobials study (NAPPA) was to characterize PK profiles of commonly used penicillins using data obtained during routine care, to further understanding of PK variability and inform future evidence-based dosing.// Methods: NAPPA was a multicentre study of amoxicillin, co-amoxiclav, benzylpenicillin, flucloxacillin and piperacillin/tazobactam. Patients were recruited with informed consent. Antibiotic dosing followed standard of care. PK samples were obtained opportunistically or at optimal times, frozen and analysed using UPLC with tandem MS. Pharmacometric analysis was undertaken using NONMEM software (v7.3). Model-based simulations (n = 10 000) tested PTA with British National Formulary for Children (BNFC) and WHO dosing. The study had ethical approval.// Results: For the combined IV PK model, 963 PK samples from 370 participants were analysed simultaneously incorporating amoxicillin, benzylpenicillin, flucloxacillin and piperacillin data. BNFC high-dose regimen simulations gave these PTA results (median fT>MIC at breakpoints of specified pathogens): amoxicillin 100% (Streptococcus pneumoniae); benzylpenicillin 100% (Group B Streptococcus); flucloxacillin 48% (MSSA); and piperacillin 100% (Pseudomonas aeruginosa). Oral population PK models for flucloxacillin and amoxicillin enabled estimation of first-order absorption rate constants (1.16 h−1 and 1.3 h−1) and bioavailability terms (62.7% and 58.7%, respectively).// Conclusions: NAPPA represents, to our knowledge, the largest prospective combined paediatric penicillin PK study undertaken to date, and the first paediatric flucloxacillin oral PK model. The PTA results provide evidence supportive of BNFC high-dose IV regimens for amoxicillin, benzylpenicillin and piperacillin

Utilization of data below the analytical limit of quantitation in pharmacokinetic analysis and modeling: promoting interdisciplinary debate

Traditionally, bioanalytical laboratories do not report actual concentrations for samples with results below the LOQ (BLQ) in pharmacokinetic studies. BLQ values are outside the method calibration range established during validation and no data are available to support the reliability of these values. However, ignoring BLQ data can contribute to bias and imprecision in model-based pharmacokinetic analyses. From this perspective, routine use of BLQ data would be advantageous. We would like to initiate an interdisciplinary debate on this important topic by summarizing the current concepts and use of BLQ data by regulators, pharmacometricians and bioanalysts. Through introducing the limit of detection and evaluating its variability, BLQ data could be released and utilized appropriately for pharmacokinetic research

Plasma and CSF pharmacokinetics of meropenem in neonates and young infants: results from the NeoMero studies.

Background: Sepsis and bacterial meningitis are major causes of mortality and morbidity in neonates and infants. Meropenem, a broad-spectrum antibiotic, is not licensed for use in neonates and infants below 3 months of age and sufficient information on its plasma and CSF disposition and dosing in neonates and infants is lacking. Objectives: To determine plasma and CSF pharmacokinetics of meropenem in neonates and young infants and the link between pharmacokinetics and clinical outcomes in babies with late-onset sepsis (LOS). Methods: Data were collected in two recently conducted studies, i.e. NeoMero-1 (neonatal LOS) and NeoMero-2 (neonatal meningitis). Optimally timed plasma samples (n = 401) from 167 patients and opportunistic CSF samples (n = 78) from 56 patients were analysed. Results: A one-compartment model with allometric scaling and fixed maturation gave adequate fit to both plasma and CSF data; the CL and volume (standardized to 70 kg) were 16.7 (95% CI 14.7, 18.9) L/h and 38.6 (95% CI 34.9, 43.4) L, respectively. CSF penetration was low (8%), but rose with increasing CSF protein, with 40% penetration predicted at a protein concentration of 6 g/L. Increased infusion time improved plasma target attainment, but lowered CSF concentrations. For 24 patients with culture-proven Gram-negative LOS, pharmacodynamic target attainment was similar regardless of the test-of-cure visit outcome. Conclusions: Simulations showed that longer infusions increase plasma PTA but decrease CSF PTA. CSF penetration is worsened with long infusions so increasing dose frequency to achieve therapeutic targets should be considered