Browsing by Subject "Monte Carlo simulations"

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    Pharmacokinetic/pharmacodynamic modeling in plasma and milk and Mote Carlo simulations of marbofloxacin against Staphylococcu aureus and Mycoplasma agalactie in lactating sheep
    (Elsevier, American Dairy Science Association, 2025-03-24) Serrano-Rodríguez, J. M.; Fernández-Varón, E.; Muñoz-Rascón, P.; Morón, R.; Díaz-Villamarín, X.; Fé Rodríguez, David Christian de la; Cárceles-García, C.; Cárceles Rodríguez, Carlos; Farmacología; Facultad de Veterinaria
    In livestock ruminants such as sheep, different infectious diseases such as mastitis or contagious agalactia are originated from pathogens as Staphylococcus aureus and Mycoplasma agalactiae. Fluoroquinolones are authorized in dairy animals, including their extralabel use, as an alternative when other treatment failed in the European Union (EU), however, in the United States, are prohibited from extralabel drug use in food-producing animals. Marbofloxacin, a well-known fluoroquinolone is commonly used in dairy cattle in the EU at 10 mg/kg. However, their off-label use in sheep also has been described. Nevertheless, the dose extrapolations from dairy cows should include pharmacokinetic (PK) studies because of interspecies differences and the potential risks of antimicrobial resistance or toxicity. In this regard, the aims of this research were to (1) describe the i.v. and i.m. PK analysis of marbofloxacin in plasma and milk of lactating sheep at 10 mg/kg, (2) determine the MIC and calculate the tentative epidemiological cutoff values (TECOFF) for Mycoplasma agalactiae and Staphylococcus aureus wild-type isolates from sheep, and (3) conduct a pharmacokinetic and pharmacodynamic (PK/PD) analysis with the Monte Carlo simulation to obtain the probability of target attainment for different MIC values, known as the PK/PD cutoff values. The results of this study could help to establish the efficacy of a 10 mg/kg dosage regimen of marbofloxacin in lactating sheep. Plasma and milk concentrations were described with a nonlinear mixed effects model. The intramuscular biobioavailability was 88%, and the volume of distribution was 1.31 L/kg with a clearance value of 0.38 L/h/kg. Halflives after i.v. and i.m. dosing were 6.53 and 7.09 h in plasma, and 6.62 and 6.65 h in milk, respectively. High concentrations were determined in milk with area under the curve (AUC) milk/plasma ratios close to 1.28. The MIC values for Staphylococcus aureus and Mycoplasma agalactiae were obtained, and TECOFF values of 1.0 and 2.0 μg/mL, respectively, were determined. The Monte Carlo simulations predicted that the dosage regimen of 10 mg/kg per 24 h in lactating sheep can be adequate for intermediate and high MIC values of 0.5 and 1.0 μg/mL, respectively, and could be useful for populations with a target AUC/MIC ratio ≤48 for Staphylococcus aureus, but not for Mycoplasma agalactiae. Results derived for this study could be taken as previous tentative points for further studies of marbofloxacin in lactating and nonlactating sheep in a clinical context.
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    Population pharmacokinetics and pharmacokinetic/pharmacodynamic evaluation of marbofloxacin against Coagulase-negative staphylococci, Staphylococcus aureus and Mycoplasma agalactie pathogens in goats
    (Elsevier, 2023-04-03) Serrano-Rodríguez, Juan Manuel; Fernández-Varón, Emilio; Cárceles Rodríguez, Carlos; San Andrés-Larrea, Manuel Ignacio; Rubio-Langre, Sonia; Fé Rodríguez, David Christian de la; Waxman Dova, Samanta; Bhardwaj, Pallavi; Sidhu, Pritam Kaur; Litterio, Nicolás Javier; Lorenzutti, Augusto Matías; Farmacología; Facultad de Veterinaria
    Marbofloxacin is a broad-spectrum fluoroquinolone, and an extra-label use has been reported in horse, sheep and goat. However, extrapolation of dosage regimens from cattle to horse and small ruminants could lead to incorrect dosing due to pharmacokinetic differences among species, increasing the risk of antimicrobial resistance or toxicity. Pharmacokinetic properties of marbofloxacin, including PK/PD analysis, have been studied by intravenous, intramuscular and subcutaneous administration in lactating and non-lactating goats. A population pharmacokinetic model of marbofloxacin in goats was built using 10 pharmacokinetic studies after intravenous, intramuscular, and subcutaneous administration at a dose of 2, 5 and 10 mg/kg. Serum or plasma and milk concentration-time profiles were simultaneously fitted with a non-linear mixed effect model with Monolix software. Level of milk production (lactating and non-lactating) and health status (healthy and un-healthy) were retained as covariates on volume of distribution and clearance. Marbofloxacin concentrations were well described in plasma/serum and milk by the population model. Simulated dose regimens of marbofloxacin administered at 2, 5 and 10 mg/kg by intramuscular route for five days were evaluated (n = 5000 per group). Steady-state fAUCs for each dose regimen were obtained. Probability of target attainment of fAUC/MIC ratios were determined and PK/PDco values (highest MIC for which 90% of individuals can achieve a prior numerical value of the fAUC/MIC index) were established using Monte Carlo simulations (n = 50,000). MIC values for wild type isolates of Staphylococcus aureus, coagulase negative staphylococci, and Mycoplasma agalactiae were determined and tentative epidemiological cutoff (TECOFF) were obtained at 1.0, 0.5 and 0.5 mg/L, respectively. The PK/PDco for the dose regimen of 2 mg/kg/24 h and 5 mg/kg/24 h (0.125 and 0.25 mg/L) were lower than TECOFF (0.5 and 1 mg/L). The dosage regimen of 10 mg/kg/24 h was adequate for intermediate MIC values of 0.125–0.50 mg/L and could be effective for a population with a target fAUC/MIC ratio ˂ 48 for Coagulase negative staphylococci and Mycoplasma agalactiae, but not for Staphylococcus aureus. Results obtained in this study could be taken as a starting point by committees that set the clinical breakpoints and justifies expert rules to optimize marbofloxacin dose regimens.
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    The effect of number of arms on the aggregation behavior of thermoresponsive poly (N-isopropylacrylamide) star polymers
    (Wiley, 2020-06-16) Zhu, Kaizheng; Pamies, Ramón; Al-Manasir, Nodar; Hernández Cifre, José G.; García de la Torre, José; Nyström, Bo; Kjøniksen, Anna-Lena; Química Física
    The thermoresponsive nature of aqueous solutions of poly(Nisopropylacrylamide) (PNIPAAM) star polymers containing 2, 3, 4, and 6 arms has been investigated by turbidity, dynamic light scattering, rheology, and rheo-SALS. Simulations of the thermosensitive nature of the single star polymers have also been conducted. Some of the samples form aggregates even at temperatures significantly below the lower critical solution temperature (LCST) of PNIPAAM. Increasing concentration and number of arms promotes associations at low temperatures. When the temperature is raised, there is a competition between size increase due to enhanced aggregation and a size reduction caused by contraction. Monte Carlo simulations show that the single stars contract with increasing temperature, and that this contraction is more pronounced when the number of arms is increased. Some samples exhibit a minimum in the turbidity data after the initial increase at the cloud point. The combined rheology and rheo-SALS data suggest that this is due to a fragmentation of the aggregates followed by re-aggregation at even higher temperatures. Although the 6-arm star polymer aggregates more than the other stars at low temperatures, the more compact structure renders it less prone to aggregation at temperatures above the cloud point.