| 1. |
- Fomalont, E. B., et al.
(författare)
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THE 2014 ALMA LONG BASELINE CAMPAIGN: AN OVERVIEW
- 2015
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 808:1
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Tidskriftsartikel (refereegranskat)abstract
- A major goal of the Atacama Large Millimeter/submillimeter Array (ALMA) is to make accurate images with resolutions of tens of milliarcseconds, which at submillimeter (submm) wavelengths requires baselines up to similar to 15 km. To develop and test this capability, a Long Baseline Campaign (LBC) was carried out from 2014 September to late November, culminating in end-to-end observations, calibrations, and imaging of selected Science Verification (SV) targets. This paper presents an overview of the campaign and its main results, including an investigation of the short-term coherence properties and systematic phase errors over the long baselines at the ALMA site, a summary of the SV targets and observations, and recommendations for science observing strategies at long baselines. Deep ALMA images of the quasar 3C 138 at 97 and 241 GHz are also compared to VLA 43 GHz results, demonstrating an agreement at a level of a few percent. As a result of the extensive program of LBC testing, the highly successful SV imaging at long baselines achieved angular resolutions as fine as 19 mas at similar to 350 GHz. Observing with ALMA on baselines of up to 15 km is now possible, and opens up new parameter space for submm astronomy.
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| 2. |
- Zvada, Simbarashe P., et al.
(författare)
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Population pharmacokinetics of rifampicin, pyrazinamide and isoniazid in children with tuberculosis : in silico evaluation of currently recommended doses
- 2014
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Ingår i: Journal of Antimicrobial Chemotherapy. - : Oxford University Press (OUP). - 0305-7453 .- 1460-2091. ; 69:5, s. 1339-1349
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Tidskriftsartikel (refereegranskat)abstract
- To describe the population pharmacokinetics of rifampicin, pyrazinamide and isoniazid in children and evaluate the adequacy of steady-state exposures. We used previously published data for 76 South African children with tuberculosis to describe the population pharmacokinetics of rifampicin, pyrazinamide and isoniazid. Monte Carlo simulations were used to predict steady-state exposures in children following doses in fixed-dose combination tablets in accordance with the revised guidelines. Reference exposures were derived from an ethnically similar adult population with tuberculosis taking currently recommended doses. The final models included allometric scaling of clearance and volume of distribution using body weight. Maturation was included for clearance of isoniazid and clearance and absorption transit time of rifampicin. For a 2-year-old child weighing 12.5 kg, the estimated typical oral clearances of rifampicin and pyrazinamide were 8.15 and 1.08 L/h, respectively. Isoniazid typical oral clearance (adjusted for bioavailability) was predicted to be 4.44, 11.6 and 14.6 L/h for slow, intermediate and fast acetylators, respectively. Higher oral clearance values in intermediate and fast acetylators also resulted from 23 lower bioavailability compared with slow acetylators. Simulations based on our models suggest that with the new WHO dosing guidelines and utilizing available paediatric fixed-dose combinations, children will receive adequate rifampicin exposures when compared with adults, but with a larger degree of variability. However, pyrazinamide and isoniazid exposures in many children will be lower than in adults. Further studies are needed to confirm these findings in children administered the revised dosages and to optimize pragmatic approaches to dosing.
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| 3. |
- Bjugård Nyberg, Henrik, 1984-, et al.
(författare)
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Population Pharmacokinetics and Dosing of Ethionamide in Children with Tuberculosis
- 2020
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Ingår i: Antimicrobial Agents and Chemotherapy. - : American Society for Microbiology. - 0066-4804 .- 1098-6596. ; 64:3
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Tidskriftsartikel (refereegranskat)abstract
- Ethionamide has proven efficacy against both drug-susceptible and some drug-resistant strains of Mycobacterium tuberculosis. Limited information on its pharmacokinetics in children is available, and current doses are extrapolated from weight-based adult doses. Pediatric doses based on more robust evidence are expected to improve antituberculosis treatment, especially in small children. In this analysis, ethionamide concentrations in children from 2 observational clinical studies conducted in Cape Town, South Africa, were pooled. All children received ethionamide once daily at a weight-based dose of approximately 20 mg/kg of body weight (range, 10.4 to 25.3 mg/kg) in combination with other first- or second-line antituberculosis medications and with antiretroviral therapy in cases of HIV coinfection. Pharmacokinetic parameters were estimated using nonlinear mixed-effects modeling. The MDR-PK1 study contributed data for 110 children on treatment for multidrug-resistant tuberculosis, while the DATiC study contributed data for 9 children treated for drug-susceptible tuberculosis. The median age of the children in the studies combined was 2.6 years (range, 0.23 to 15 years), and the median weight was 12.5 kg (range, 2.5 to 66 kg). A one-compartment, transit absorption model with first-order elimination best described ethionamide pharmacokinetics in children. Allometric scaling of clearance (typical value, 8.88 liters/h), the volume of distribution (typical value, 21.4 liters), and maturation of clearance and absorption improved the model fit. HIV coinfection decreased the ethionamide bioavailability by 22%, rifampin coadministration increased clearance by 16%, and ethionamide administration by use of a nasogastric tube increased the rate, but the not extent, of absorption. The developed model was used to predict pediatric doses achieving the same drug exposure achieved in 50- to 70-kg adults receiving 750-mg once-daily dosing. Based on model predictions, we recommend a weight-banded pediatric dosing scheme using scored 125-mg tablets.
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| 4. |
- Gafar, Fajri, et al.
(författare)
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Global estimates and determinants of antituberculosis drug pharmacokinetics in children and adolescents : a systematic review and individual patient data meta-analysis
- 2023
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Ingår i: European Respiratory Journal. - : European Respiratory Society. - 0903-1936 .- 1399-3003. ; 61:3
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Forskningsöversikt (refereegranskat)abstract
- Background Suboptimal exposure to antituberculosis (anti-TB) drugs has been associated with unfavourable treatment outcomes. We aimed to investigate estimates and determinants of first-line anti-TB drug pharmacokinetics in children and adolescents at a global level.Methods We systematically searched MEDLINE, Embase and Web of Science (1990–2021) for pharmacokinetic studies of first-line anti-TB drugs in children and adolescents. Individual patient data were obtained from authors of eligible studies. Summary estimates of total/extrapolated area under the plasma concentration–time curve from 0 to 24 h post-dose (AUC0–24) and peak plasma concentration (Cmax) were assessed with random-effects models, normalised with current World Health Organization-recommended paediatric doses. Determinants of AUC0–24 and Cmax were assessed with linear mixed-effects models.Results Of 55 eligible studies, individual patient data were available for 39 (71%), including 1628 participants from 12 countries. Geometric means of steady-state AUC0–24 were summarised for isoniazid (18.7 (95% CI 15.5–22.6) h·mg·L−1), rifampicin (34.4 (95% CI 29.4–40.3) h·mg·L−1), pyrazinamide (375.0 (95% CI 339.9–413.7) h·mg·L−1) and ethambutol (8.0 (95% CI 6.4–10.0) h·mg·L−1). Our multivariate models indicated that younger age (especially <2 years) and HIV-positive status were associated with lower AUC0–24 for all first-line anti-TB drugs, while severe malnutrition was associated with lower AUC0–24 for isoniazid and pyrazinamide. N-acetyltransferase 2 rapid acetylators had lower isoniazid AUC0–24 and slow acetylators had higher isoniazid AUC0–24 than intermediate acetylators. Determinants of Cmax were generally similar to those for AUC0–24.Conclusions This study provides the most comprehensive estimates of plasma exposures to first-line anti-TB drugs in children and adolescents. Key determinants of drug exposures were identified. These may be relevant for population-specific dose adjustment or individualised therapeutic drug monitoring.
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| 5. |
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| 6. |
- Garcia-Prats, Anthony J., et al.
(författare)
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Pharmacokinetics and safety of high-dose rifampicin in children with TB : the Opti-Rif trial
- 2021
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Ingår i: Journal of Antimicrobial Chemotherapy. - : Oxford University Press. - 0305-7453 .- 1460-2091. ; 76:12, s. 3237-3246
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Tidskriftsartikel (refereegranskat)abstract
- Background: Rifampicin doses of 40 mg/kg in adults are safe and well tolerated, may shorten anti-TB treatment and improve outcomes, but have not been evaluated in children. Objectives: To characterize the pharmacokinetics and safety of high rifampicin doses in children with drug-susceptible TB. Patients and methods: The Opti-Rif trial enrolled dosing cohorts of 20 children aged 0-12 years, with incremental dose escalation with each subsequent cohort, until achievement of target exposures or safety concerns. Cohort 1 opened with a rifampicin dose of 15 mg/kg for 14 days, with a single higher dose (35 mg/kg) on day 15. Pharmacokinetic data from days 14 and 15 were analysed using population modelling and safety data reviewed. Incrementally increased rifampicin doses for the next cohort (days 1-14 and day 15) were simulated from the updated model, up to the dose expected to achieve the target exposure [235 mg/L.h, the geometric mean area under the concentration-time curve from 0 to 24h (AUC(0-24)) among adults receiving a 35mg/kg dose]. Results: Sixty-two children were enrolled in three cohorts. The median age overall was 2.1 years (range=0.4-11.7). Evaluated doses were similar to 35 mg/kg (days 1-14) and similar to 50 mg/kg (day 15) for cohort 2 and similar to 60 mg/kg (days 1-14) and similar to 75mg/kg (day 15) for cohort 3. Approximately half of participants had an adverse event related to study rifampicin; none was grade 3 or higher. A 65-70 mg/kg rifampicin dose was needed in children to reach the target exposure. Conclusions: High rifampicin doses in children achieved target exposures and the doses evaluated were safe over 2 weeks.
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