scholarly journals Population Pharmacokinetics of Teicoplanin in Preterm and Term Neonates: Is It Time for a New Dosing Regimen?

2020 ◽  
Vol 64 (4) ◽  
Author(s):  
A. Kontou ◽  
K. Sarafidis ◽  
O. Begou ◽  
H. G. Gika ◽  
A. Tsiligiannis ◽  
...  
Keyword(s):  
Creatinine Clearance ◽  
Maintenance Dose ◽  
Plasma Concentrations ◽  
Central Compartment ◽  
Preterm Neonates ◽  
Peripheral Compartment ◽  
Population Pharmacokinetic ◽  
Dosing Regimen ◽  
Time Curve ◽  
Content Type

ABSTRACT Our objective was to develop a population pharmacokinetic (PK) model in order to evaluate the currently recommended dosing regimen in term and preterm neonates. By using an optimal design approach, a prospective PK study was designed and implemented in 60 neonates with postmenstrual ages (PMA) of 26 to 43 weeks. A loading dose of 16 mg/kg was administered at day 1, followed by a maintenance dose of 8 mg/kg daily. Plasma concentrations were quantified by high-pressure liquid chromatography–mass spectrometry. Population PK (popPK) analysis was performed using NONMEM software. Monte-Carlo (MC) simulations were performed to evaluate currently recommended dosing based on a pharmacodynamic index of area under the concentration-time curve (AUC)/MIC ratio of ≥400. A two-compartment model with linear elimination best described the data by the following equations: clearance (CL) = 0.0227 × (weight [wt]/1,765)0.75 × (estimated creatinine clearance [eCRCL]/22)0.672, central compartment volume of distribution (V1) = 0.283 (wt/1,765), intercompartmental clearance (Q) = 0.151 (wt/1,765)0.75, and peripheral compartment volume (V2) = 0.541 (wt/1,765). The interindividual variability estimates for CL, V1, and V2 were 36.5%, 45.7%, and 51.4%, respectively. Current weight (wt) and estimated creatinine clearance (eCRCL) significantly explained the observed variability. MC simulation demonstrated that, with the current dosing regimen, an AUC/MIC ratio of ≥400 was reached by only 68.5% of neonates with wt of <1 kg when the MIC was equal to 1 mg/kg, versus 82.2%, 89.7%, and 92.7% of neonates with wt of 1 to <2, 2 to <3, or ≥3 kg, respectively. Augmentation of a maintenance dose up to 10 or 11 mg/kg for preterm neonates with wt of 1 to <2 or <1 kg, respectively, increases the probability of reaching the therapeutic target; the recommended doses seem to be adequate for neonates with wt of ≥2 kg. Teicoplanin PK are variable in neonates, with wt and eCRCL having the most significant impact. Neonates with wt of <2 kg need higher doses, especially for Staphylococcus spp. with an MIC value of ≥1 mg/liter.

scholarly journals Population Pharmacokinetic Modeling as a Tool To Characterize the Decrease in Ciprofloxacin Free Interstitial Levels Caused by Pseudomonas aeruginosa Biofilm Lung Infection in Wistar Rats

2017 ◽  
Vol 61 (7) ◽  
Author(s):  
Bruna G. S. Torres ◽  
Victória E. Helfer ◽  
Priscila M. Bernardes ◽  
Alexandre José Macedo ◽  
Elisabet I. Nielsen ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Tissue Concentration ◽  
Plasma Concentrations ◽  
Central Compartment ◽  
Population Pharmacokinetic ◽  
Plasma Exposure ◽  
Time Curve ◽  
Content Type ◽  
Population Pharmacokinetic Modeling ◽  
Free Interstitial

ABSTRACT Biofilm formation plays an important role in the persistence of pulmonary infections, for example, in cystic fibrosis patients. So far, little is known about the antimicrobial lung disposition in biofilm-associated pneumonia. This study aimed to evaluate, by microdialysis, ciprofloxacin (CIP) penetration into the lungs of healthy and Pseudomonas aeruginosa biofilm-infected rats and to develop a comprehensive model to describe the CIP disposition under both conditions. P. aeruginosa was immobilized into alginate beads and intratracheally inoculated 14 days before CIP administration (20 mg/kg of body weight). Plasma and microdialysate were sampled from different animal groups, and the observations were evaluated by noncompartmental analysis (NCA) and population pharmacokinetic (popPK) analysis. The final model that successfully described all data consisted of an arterial and a venous central compartment and two peripheral distribution compartments, and the disposition in the lung was modeled as a two-compartment model structure linked to the venous compartment. Plasma clearance was approximately 32% lower in infected animals, leading to a significantly higher level of plasma CIP exposure (area under the concentration-time curve from time zero to infinity, 27.3 ± 12.1 μg · h/ml and 13.3 ± 3.5 μg · h/ml in infected and healthy rats, respectively). Despite the plasma exposure, infected animals showed a four times lower tissue concentration/plasma concentration ratio (lung penetration factor = 0.44 and 1.69 in infected and healthy rats, respectively), and lung clearance (CLlung) was added to the model for these animals (CLlung = 0.643 liters/h/kg) to explain the lower tissue concentrations. Our results indicate that P. aeruginosa biofilm infection reduces the CIP free interstitial lung concentrations and increases plasma exposure, suggesting that plasma concentrations alone are not a good surrogate of lung concentrations.

scholarly journals Population Pharmacokinetics and Cerebrospinal Fluid Penetration of Fluconazole in Adults with Cryptococcal Meningitis

2018 ◽  
Vol 62 (9) ◽  
Author(s):  
Katharine E. Stott ◽  
Justin Beardsley ◽  
Ruwanthi Kolamunnage-Dona ◽  
Anahi Santoyo Castelazo ◽  
Freddie Mukasa Kibengo ◽  
...  
Keyword(s):  
Cerebrospinal Fluid ◽  
Standard Deviation ◽  
Cryptococcal Meningitis ◽  
Meta Analysis ◽  
Central Compartment ◽  
Order Rate Constant ◽  
Peripheral Compartment ◽  
Population Pharmacokinetic ◽  
Time Curve ◽  
Content Type

ABSTRACTRobust population pharmacokinetic (PK) data for fluconazole are scarce. The variability of fluconazole penetration into the central nervous system (CNS) is not known. A fluconazole PK study was conducted in 43 patients receiving oral fluconazole (usually 800 mg every 24 h [q24h]) in combination with amphotericin B deoxycholate (1 mg/kg q24h) for cryptococcal meningitis (CM). A four-compartment PK model was developed, and Monte Carlo simulations were performed for a range of fluconazole dosages. A meta-analysis of trials reporting outcomes of CM patients treated with fluconazole monotherapy was performed. Adjusted for bioavailability, the PK parameter means (standard deviation) were the following: clearance, 0.72 (0.24) liters/h; volume of the central compartment, 18.07 (6.31) liters; volume of the CNS compartment, 32.07 (17.60) liters; first-order rate constant from the central to peripheral compartment, 12.20 (11.17) h−1, from the peripheral to central compartment, 18.10 (8.25) h−1, from the central to CNS compartment, 35.43 (13.74) h−1, and from the CNS to central the compartment, 28.63 (10.03) h−1. Simulations of the area under concentration-time curve resulted in median (interquartile range) values of 1,143.2 (range, 988.4 to 1,378.0) mg · h/liter in plasma (AUCplasma) and 982.9 (range, 781.0 to 1,185.9) mg · h/liter in cerebrospinal fluid (AUCCSF) after a dosage of 1,200 mg q24h. The mean simulated ratio of AUCCSF/AUCplasmawas 0.89 (standard deviation [SD], 0.44). The recommended dosage of fluconazole for CM induction therapy fails to attain the pharmacodynamic (PD) target in respect to the wild-type MIC distribution forC. neoformans. The meta-analysis suggested modest improvements in both CSF sterility and mortality outcomes with escalating dosage. This study provides the pharmacodynamic rationale for the long-recognized fact that fluconazole monotherapy is an inadequate induction regimen for CM.

scholarly journals Isavuconazole Population Pharmacokinetic Analysis Using Nonparametric Estimation in Patients with Invasive Fungal Disease (Results from the VITAL Study)

2016 ◽  
Vol 60 (8) ◽  
pp. 4568-4576 ◽  
Author(s):  
Laura L. Kovanda ◽  
Amit V. Desai ◽  
Qiaoyang Lu ◽  
Robert W. Townsend ◽  
Shahzad Akhtar ◽  
...  
Keyword(s):  
Nonparametric Estimation ◽  
Invasive Fungal Disease ◽  
Fungal Disease ◽  
Water Soluble ◽  
Pharmacokinetic Analysis ◽  
Population Pharmacokinetic ◽  
Dosing Regimen ◽  
Open Label ◽  
Time Curve ◽  
Content Type

ABSTRACTIsavuconazonium sulfate (Cresemba; Astellas Pharma Inc.), a water-soluble prodrug of the triazole antifungal agent isavuconazole, is available for the treatment of invasive aspergillosis (IA) and invasive mucormycosis. A population pharmacokinetic (PPK) model was constructed using nonparametric estimation to compare the pharmacokinetic (PK) behaviors of isavuconazole in patients treated in the phase 3 VITAL open-label clinical trial, which evaluated the efficacy and safety of the drug for treatment of renally impaired IA patients and patients with invasive fungal disease (IFD) caused by emerging molds, yeasts, and dimorphic fungi. Covariates examined were body mass index (BMI), weight, race, impact of estimated glomerular filtration rate (eGFR) on clearance (CL), and impact of weight on volume. PK parameters were compared based on IFD type and other patient characteristics. Simulations were performed to describe the MICs covered by the clinical dosing regimen. Concentrations (n= 458) from 136 patients were used to construct a 2-compartment model (first-order absorption compartment and central compartment). Weight-related covariates affected clearance, but eGFR did not. PK parameters and intersubject variability of CL were similar across different IFD groups and populations. Target attainment analyses demonstrated that the clinical dosing regimen would be sufficient for total drug area under the concentration-time curve (AUC)/MIC targets ranging from 50.5 forAspergillusspp. (up to the CLSI MIC of 0.5 mg/liter) to 270 and 5,053 forCandida albicans(up to MICs of 0.125 and 0.004 mg/liter, respectively) and 312 for non-albicans Candidaspp. (up to a MIC of 0.125 mg/liter). The estimations forCandidaspp. were exploratory considering that no patients withCandidainfections were included in the current analyses. (The VITAL trial is registered at ClinicalTrials.gov under number NCT00634049.)

scholarly journals Nemonoxacin Dosage Adjustment in Patients with Severe Renal Impairment Based on Population Pharmacokinetic and Pharmacodynamic Analysis

2021 ◽  
Author(s):  
Yi Li ◽  
Jianda Lu ◽  
Yue Kang ◽  
Xiaoyong Xu ◽  
Xin Li ◽  
...  
Keyword(s):  
Renal Impairment ◽  
Severe Renal Impairment ◽  
Compartment Model ◽  
Central Compartment ◽  
Peripheral Compartment ◽  
Population Pharmacokinetic ◽  
Healthy Controls ◽  
Dosing Regimen ◽  
Open Label ◽  
Optimal Dosing

Aims: To optimize the dosing regimen in patients with severe renal impairment based on population pharmacokinetic/pharmacodynamic (PPK/PD) analysis. Methods: The pharmacokinetics and safety of nemonoxacin was evaluated in a single-dose, open-label, nonrandomized, parallel-group study after single oral dose of 0.5 g nemonoxacin capsule in 10 patients with severe renal impairment and 10 healthy controls. Both blood and urine samples were collected within 48 hours after admission and determined the concentrations. A PPK model was built using nonlinear mixed effects modelling. The probability of target attainment (PTA) and the cumulative fraction of response (CFR) against S. Pneumoniae and S. aureus was calculated by Monte Carlo simulation. Results: The data best fitted to a two-compartment model, from which the PPK parameters were estimated, including clearance (8.55 L/h), central compartment volume (80.8 L), and peripheral compartment volume (50.6 L). The accumulative urinary excretion was 23.4±6.5% in severe renal impairment patients and 66.1±16.8% in healthy controls. PPK/PD modeling and simulation of 4 dosage regimens found that nemonoxacin 0.5 g q48h was the optimal dosing regimen in severe renal impairment patients, evidenced by higher PTA (92.7%) and CFR (>99%) at nemonoxacin MIC ≤ 1 mg/L against S. pneumoniae and S. aureus. The alternative regimens (0.25 g q24h; loading dose 0.5 g on Day 1 followed by 0.25 g q24h) were insufficient to cover the pathogens even if MIC ≤ 0.5 mg/L. Conclusion: An extended dosing interval (0.5 g q48h) may be appropriate for optimal efficacy of nemonoxacin in case of severe renal impairment.

scholarly journals O15 Lidocaine plasma concentrations and anti-epileptic efficacy in term and preterm neonates: prospective validation of a new dosing regimen

2019 ◽  
Vol 104 (6) ◽  
pp. e7.1-e7
Author(s):  
L Favié ◽  
C Rademaker ◽  
M van den Broek ◽  
T Egberts ◽  
F van Bel ◽  
...  
Keyword(s):  
Neonatal Intensive Care ◽  
Cardiac Toxicity ◽  
Plasma Concentrations ◽  
Maintenance Phase ◽  
Similar Efficacy ◽  
Preterm Neonates ◽  
Population Pharmacokinetic ◽  
List Type ◽  
Dosing Regimen ◽  
Wide Scale

BackgroundLidocaine is used as an add-on anti-epileptic drug (AED) in neonates when seizures persist despite treatment with first line anticonvulsants. Although lidocaine has shown to be an effective anticonvulsant, cardiac toxicity associated with plasma concentrations >9 mg/L have limited its wide scale use.1 Previous studies from our group have proposed a dosing regimen for effective and safe lidocaine use in term and preterm neonates with plasma concentrations not exceeding 9 mg/L.2,3AimThe present study evaluated lidocaine use as anticonvulsant in neonates and prospectively validated the new dosing regimen.MethodsData were collected at the neonatal intensive care unit of the University Medical Centre Utrecht. Neonates refractory to at least one AED received lidocaine according to clinical protocol. Lidocaine was administered as a 2 mg/kg loading dose in 10 minutes followed by a three stage maintenance phase with tapering lidocaine doses. Lidocaine plasma concentrations were measured from blood samples taken at the end of the first stage (highest lidocaine dose) and during the second or third stage (tapered lidocaine dose). Efficacy was determined as abolishment of seizures during lidocaine therapy and no recurrence within 24 h after cessation.ResultsLidocaine data were available from 75 neonates (gestational age 36.2 weeks [range 25.0–42.4, < 36.0 38.7%], birth weight 2771 g [range 675–4875], male 64.0%, mortality 45.3%). 23 patients (30.7%) received the new dosing regimen, 52 patients (60.7%) the old regimen. Highest measured plasma concentration with the new regimen was 9.15 mg/L and 16.8 mg/L with the old regimen. Efficacy with the new regimen was 56.5% and 53.8% for the old regimen. No cardiac toxicity was observed in either group.ConclusionsThe new lidocaine dosing regimen leads to safe and effective lidocaine plasma concentrations and has similar efficacy compared to the previous dosing regimen.ReferencesWeeke LC, Toet MC, Van Rooij LGM, Groenendaal F, Boylan GB, Pressler RM, et al. Lidocaine response rate in aEEG-confirmed neonatal seizures: Retrospective study of 413 full-term and preterm infants 2015;233–42.Van den Broek MPH, Rademaker CMA, van Straaten HLM, Huitema ADR, Toet MC, de Vries LS, et al. Anticonvulsant treatment of asphyxiated newborns under hypothermia with lidocaine: efficacy, safety and dosing. Arch Dis Child Fetal Neonatal Ed 2013;98(4):F341–5.Van Den Broek MPH, Huitema a. DR, Van Hasselt JGC, Groenendaal F, Toet MC, Egberts TCG, et al. Lidocaine (lignocaine) dosing regimen based upon a population pharmacokinetic model for preterm and term neonates with seizures. Clin Pharmacokinet 2011;50(7):461–9.Disclosure(s)Nothing to disclose

scholarly journals Pharmacokinetics of Telavancin in Adult Patients with Cystic Fibrosis during Acute Pulmonary Exacerbation

2019 ◽  
Vol 64 (1) ◽  
Author(s):  
James M. Kidd ◽  
Colleen M. Sakon ◽  
Louise-Marie Oleksiuk ◽  
Jeffrey J. Cies ◽  
Rebecca S. Pettit ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Body Weight ◽  
Total Body Weight ◽  
Central Compartment ◽  
Volume Of Distribution ◽  
Peripheral Compartment ◽  
Population Pharmacokinetic ◽  
Minimal Risk ◽  
Content Type ◽  
Total Body

ABSTRACT Adults with cystic fibrosis (CF) frequently harbor Staphylococcus aureus, which is increasingly antibiotic resistant. Telavancin is a once-daily rapidly bactericidal antibiotic active against methicillin-, linezolid-, and ceftaroline-resistant S. aureus. Because CF patients experience alterations in pharmacokinetics, the optimal dose of telavancin in this population is unknown. Adult CF patients (n = 18) admitted for exacerbations received 3 doses of telavancin 7.5 mg/kg of body weight (first 6 patients) or 10 mg/kg (final 12 patients) every 24 h (q24h). Population pharmacokinetic models with and without covariates were fitted using the nonparametric adaptive grid algorithm in Pmetrics. The final model was used to perform 5,000-patient Monte Carlo simulations for multiple telavancin doses. The best fit was a 2-compartment model describing the volume of distribution of the central compartment (Vc) as a multiple of total body weight (TBW) and the volume of distribution of the central compartment scaled to total body weight (Vθ) normalized by the median observed value (Vc = Vθ × TBW/52.1) and total body clearance (CL) as a linear function of creatinine clearance (CRCL) (CL = CLNR + CLθ × CRCL), where CLNR represents nonrenal clearance and CLθ represents the slope term on CRCL to estimate renal clearance. The mean population parameters were as follows: Vθ, 4.92  ± 0.76 liters · kg−1; CLNR, 0.59  ± 0.30 liters · h−1; CLθ, 5.97 × 10−3 ± 1.24 × 10−3; Vp (volume of the peripheral compartment), 3.77  ± 1.41 liters; Q (intercompartmental clearance), 4.08  ± 2.17 liters · h−1. The free area under the concentration-time curve (fAUC) values for 7.5 and 10 mg/kg were 30  ± 4.6 and 52  ± 12 mg · h/liter, respectively. Doses of 7.5 mg/kg and 10 mg/kg achieved 76.5% and 100% probability of target attainment (PTA) at a fAUC/MIC threshold of >215, respectively, for MIC of ≤0.12 mg/liter. The probabilities of reaching the acute kidney injury (AKI) threshold AUC (763 mg · h · liter−1) for these doses were 0% and 0.96%, respectively. No serious adverse events occurred. Telavancin 10 mg/kg yielded optimal PTA and minimal risk of AKI, suggesting that this FDA-approved dose is appropriate to treat acute pulmonary exacerbations in CF adults. (The clinical trial discussed in this study has been registered at ClinicalTrials.gov under identifier NCT03172793.)

scholarly journals Caspofungin Weight-Based Dosing Supported by a Population Pharmacokinetic Model in Critically Ill Patients

2020 ◽  
Vol 64 (9) ◽  
Author(s):  
Anne-Grete Märtson ◽  
Kim C. M. van der Elst ◽  
Anette Veringa ◽  
Jan G. Zijlstra ◽  
Albertus Beishuizen ◽  
...  
Keyword(s):  
Critically Ill ◽  
Rate Constant ◽  
Critically Ill Patients ◽  
Population Pharmacokinetic Model ◽  
Pharmacokinetic Model ◽  
Central Compartment ◽  
Peripheral Compartment ◽  
Population Pharmacokinetic ◽  
Content Type ◽  
The Mean

ABSTRACT The objective of this study was to develop a population pharmacokinetic model and to determine a dosing regimen for caspofungin in critically ill patients. Nine blood samples were drawn per dosing occasion. Fifteen patients with (suspected) invasive candidiasis had one dosing occasion and five had two dosing occasions, measured on day 3 (±1) of treatment. Pmetrics was used for population pharmacokinetic modeling and probability of target attainment (PTA). A target 24-h area under the concentration-time curve (AUC) value of 98 mg·h/liter was used as an efficacy parameter. Secondarily, the AUC/MIC targets of 450, 865, and 1,185 were used to calculate PTAs for Candida glabrata, C. albicans, and C. parapsilosis, respectively. The final 2-compartment model included weight as a covariate on volume of distribution (V). The mean V of the central compartment was 7.71 (standard deviation [SD], 2.70) liters/kg of body weight, the mean elimination constant (Ke) was 0.09 (SD, 0.04) h−1, the rate constant for the caspofungin distribution from the central to the peripheral compartment was 0.44 (SD, 0.39) h−1, and the rate constant for the caspofungin distribution from the peripheral to the central compartment was 0.46 (SD, 0.35) h−1. A loading dose of 2 mg/kg on the first day, followed by 1.25 mg/kg as a maintenance dose, was chosen. With this dose, 98% of the patients were expected to reach the AUC target on the first day and 100% of the patients on the third day. The registered caspofungin dose might not be suitable for critically ill patients who were all overweight (≥120 kg), over 80% of median weight (78 kg), and around 25% of lower weight (≤50 kg). A weight-based dose regimen might be appropriate for achieving adequate exposure of caspofungin in intensive care unit patients.

scholarly journals Pharmacokinetics of Intravenous and Oral Linezolid in Adults with Cystic Fibrosis

2011 ◽  
Vol 55 (7) ◽  
pp. 3393-3398 ◽  
Author(s):  
Rebecca A. Keel ◽  
Andre Schaeftlein ◽  
Charlotte Kloft ◽  
J. Samuel Pope ◽  
R. Frederic Knauft ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Compartment Model ◽  
Central Compartment ◽  
Time Dependent ◽  
Peripheral Compartment ◽  
Population Pharmacokinetic ◽  
Parameter Estimates ◽  
Content Type ◽  
Mixed Effects Modeling ◽  
Dosing Regimens

ABSTRACTLinezolid is a treatment option for methicillin-resistantStaphylococcus aureus(MRSA) infections in cystic fibrosis (CF) patients. Little is known, however, about its pharmacokinetics in this population. Eight adults with CF were randomized to receive intravenous (i.v.) and oral linezolid at 600 mg twice daily for 9 doses in a crossover design with a 9-day washout. Plasma samples were collected after the first and ninth doses of each phase. Population pharmacokinetic analyses were performed by nonlinear mixed-effects modeling using a previously described 2-compartment model with time-dependent clearance inhibition. Monte Carlo simulation was performed to assess the activities of the linezolid dosing regimens against 42 contemporary MRSA isolates recovered from CF patients. The following pharmacokinetic parameter estimates were observed for the population: absorption rate constant, 1.91 h−1; clearance, 9.54 liters/h; volume of central compartment, 26.8 liters; volume of peripheral compartment, 17.3 liters; and intercompartmental clearance, 104 liters/h. Linezolid demonstrated nonlinear clearance after 9 doses, which was reduced by a mean of 38.9% (range, 28.8 to 59.9%). Mean bioavailability was 85% (range, 47 to 131%). At steady state, 600 mg given twice daily produced 93.0% and 87.2% probabilities of obtaining the target pharmacodynamic exposure against the MRSA isolates for the i.v. and oral formulations, respectively. Thrice-daily dosing increased the probabilities to 97.0% and 95.6%, respectively. Linezolid pharmacokinetics in these adults with CF were well described by a 2-compartment model with time-dependent clearance inhibition. Standard i.v. and oral dosing regimens should be sufficient to reliably attain pharmacodynamic targets against most MRSA isolates; however, more frequent dosing may be required for isolates with MICs of ≥2 μg/ml.

scholarly journals Population Pharmacokinetic and Pharmacodynamic Analysis of Linezolid and a Hematologic Side Effect, Thrombocytopenia, in Japanese Patients

2011 ◽  
Vol 55 (5) ◽  
pp. 1867-1873 ◽  
Author(s):  
Tomohiro Sasaki ◽  
Hiroshi Takane ◽  
Katsuhiro Ogawa ◽  
Sayaka Isagawa ◽  
Takeshi Hirota ◽  
...  
Keyword(s):  
Renal Function ◽  
Liver Cirrhosis ◽  
Creatinine Clearance ◽  
Side Effect ◽  
Population Pharmacokinetic ◽  
Severe Liver ◽  
Time Curve ◽  
Content Type ◽  
Platelet Counts ◽  
The Relationship

ABSTRACTLinezolid is an antimicrobial agent to treat infections by Gram-positive pathogens, including methicillin-resistantStaphylococcus aureus(MRSA). While effective, linezolid treatment frequently is associated with hematological side effects, especially thrombocytopenia. However, little is known about the mechanism of this side effect and the exposure-response relationship. The present population pharmacokinetic/pharmacodynamic (PPK/PD) study was undertaken to elucidate the factors that determine linezolid levels, the relationship between exposure to linezolid and a decrease in platelet counts, and appropriate dosage adjustments based on exposure levels. In total, 50 patients (135 plasma samples) were used for the PPK analysis. The PPK analysis revealed that renal function and severe liver cirrhosis (Child Pugh grade C) significantly affect the pharmacokinetics of linezolid according to the equation clearance (liter/h) = 2.85 × (creatinine clearance/60.9)0.618× 0.472CIR(CIR indicates cirrhosis status; 0 for noncirrhosis, 1 for cirrhosis patients). Using 603 platelet counts from 45 patients, a PPK/PD analysis with a semimechanistic pharmacodynamic model described the relationship between linezolid exposure and platelet counts quantitatively, and the newly constructed model was validated using external data (776 platelet counts from 60 patients). Simulation indicated considerable risks in patients with insufficient renal function (creatinine clearance, ≤30 ml/min) or severe liver cirrhosis. For these patients, a reduced dosage (600 mg/day) would be recommended for sufficient efficacy (area under the concentration-time curve over 24 h in the steady state divided by the MIC, >100) and safety.

scholarly journals Population Pharmacokinetics and Pharmacodynamics of Levofloxacin in Acutely Hospitalized Older Patients with Various Degrees of Renal Function

2016 ◽  
Vol 61 (3) ◽  
Author(s):  
Pier Giorgio Cojutti ◽  
Virginia Ramos-Martin ◽  
Isabella Schiavon ◽  
Paolo Rossi ◽  
Massimo Baraldo ◽  
...  
Keyword(s):  
Renal Function ◽  
Clinical Outcome ◽  
Creatinine Clearance ◽  
Population Pharmacokinetics ◽  
Older Patients ◽  
Classification And Regression Tree ◽  
Therapeutic Drug ◽  
Time Curve ◽  
Content Type ◽  
Cart Analysis

ABSTRACT A retrospective study was conducted in a large sample of acutely hospitalized older patients who underwent therapeutic drug monitoring during levofloxacin treatment. The aim was to assess the population pharmacokinetics (popPK) and pharmacodynamics of levofloxacin among older patients. PopPK and Monte Carlo simulation were performed to define the permissible doses in older patients according to various degrees of renal function. Classification and regression tree (CART) analysis was used to detect the cutoff 24-hour area under the concentration-time curve (AUC24)/MIC ratio that best correlated with the clinical outcome. The probability of target attainment (PTA) of this value was calculated against different pathogens. A total of 168 patients were included, and 330 trough and 239 peak concentrations were used for the popPK analysis. Creatinine clearance (CrCL) was the only covariate that improved the model fit (levofloxacin CL = 0.399 + 0.051 × CrCLCKD-EPI [creatinine clearance estimated by means of the chronic kidney disease epidemiology]). Drug doses ranged between 500 mg every 48 h and 500 mg every 12 h in relation to different renal functions. The identified cutoff AUC24/MIC ratio (≥95.7) was the only covariate that correlated with a favorable clinical outcome in multivariate regression analysis (odds ratio [OR], 20.85; 95% confidence interval [CI], 1.56 to 186.73). PTAs were optimal (>80%) against Escherichia coli and Haemophilus influenzae, borderline against Staphylococcus aureus, and suboptimal against Pseudomonas aeruginosa. The levofloxacin doses defined in our study may be effective for the treatment of infections due to bacterial pathogens, with an MIC of ≤0.5 mg/liter in older patients with various degrees of renal function, while minimizing the toxicity risk. Conversely, the addition of another active antimicrobial should be considered whenever treating infections caused by less susceptible pathogens.

Sign in / Sign up

Export Citation Format

Share Document