scholarly journals Designing Fluoroquinolone Breakpoints for Streptococcus pneumoniae by Using Genetics instead of Pharmacokinetics-Pharmacodynamics

2004 ◽  
Vol 48 (9) ◽  
pp. 3630-3635 ◽  
Author(s):  
H. J. Smith ◽  
A. M. Noreddin ◽  
C. G. Siemens ◽  
K. N. Schurek ◽  
J. Greisman ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Streptococcus Pneumoniae ◽  
Monte Carlo Simulations ◽  
Free Drug ◽  
Target Attainment ◽  
Time Curve ◽  
Once Daily ◽  
Concentration Time ◽  
Bacteriological Eradication ◽  
High Level

ABSTRACT We determined fluoroquinolone microbiological resistance breakpoints for Streptococcus pneumoniae by using genetic instead of pharmacokinetic-pharmacodynamic parameters. The proposed microbiological breakpoints define resistance as the MIC at which >50% of the isolates carry quinolone resistance-determining region mutations and/or, if data are available, when Monte Carlo simulations demonstrate a <90% chance of bacteriological eradication. The proposed microbiological resistant breakpoints are as follows (in micrograms per milliliter): gatifloxacin, >0.25; gemifloxacin, >0.03; levofloxacin, >1; and moxifloxacin, >0.12. Monte Carlo simulations of the once daily 400-mg doses of gatifloxacin and 750-mg doses levofloxacin demonstrated a high level of target attainment (free-drug area under the concentration-time curve from 0 to 24 h/MIC ratio of 30) by using these new genetically derived breakpoints.

scholarly journals Population Pharmacokinetics of Linezolid in Adults with Pulmonary Tuberculosis

2009 ◽  
Vol 53 (9) ◽  
pp. 3981-3984 ◽  
Author(s):  
Bryan McGee ◽  
Reynaldo Dietze ◽  
David Jamil Hadad ◽  
Lucilia Pereira Dutra Molino ◽  
Ethel Leonor Noia Maciel ◽  
...  
Keyword(s):  
Pulmonary Tuberculosis ◽  
Rate Constant ◽  
Population Model ◽  
Absorption Rate ◽  
Elimination Rate ◽  
Volume Of Distribution ◽  
Free Drug ◽  
Time Curve ◽  
Once Daily ◽  
Concentration Time

ABSTRACT Nineteen adults with pulmonary tuberculosis received linezolid (600 mg) once or twice daily in an early bactericidal activity trial. A one-compartment population model produced median values for the absorption rate constant, volume of distribution, and elimination rate constant of 1.5 h−1, 29.6 liters, and 0.25 h−1 (once daily) and 2.7 h−1, 32.1 liters, and 0.15 h−1 (twice daily). Linezolid administered twice daily produced higher values for free drug area under the concentration-time curve (AUC)/MIC and time above MIC. Both regimens achieved free AUC/MIC ratios > 100. Median times above the MIC for free drug were 100% (twice daily) and 63% (once daily).

scholarly journals Optimizing gentamicin dosing in different pediatric age groups using population pharmacokinetics and Monte Carlo simulation

2021 ◽  
Vol 47 (1) ◽  
Author(s):  
Ragia H. Ghoneim ◽  
Abrar K. Thabit ◽  
Manar O. Lashkar ◽  
Ahmed S. Ali
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Population Pharmacokinetics ◽  
Pharmacokinetic Model ◽  
Population Pharmacokinetic ◽  
Target Attainment ◽  
Concentration Data ◽  
Once Daily ◽  
Dosing Regimens ◽  
Gentamicin Concentration

Abstract Introduction The use of once daily dosing of aminoglycosides in pediatrics is increasing but studies on dose optimization targeting the pediatric population are limited. This study aimed to derive a population pharmacokinetic model of gentamicin and apply it to design optimal dosing regimens in pediatrics. Methods Population pharmacokinetics of gentamicin in pediatrics was described from a retrospective chart review of plasma gentamicin concentration data (peak/ trough levels) of pediatric patients (1 month − 12 years), admitted to non-critically ill pediatrics. Monte Carlo simulations were performed on the resulting pharmacokinetic model to assess the probability of achieving a Cmax/MIC target of 10 mg/L over a range of gentamicin MICs of 0.5–2 mg/L and once daily gentamicin dosing regimens. Results: A two-compartment model with additive residual error best described the model with weight incorporated as a significant covariate for both clearance and volume of distribution. Monte Carlo simulations demonstrated a good probability of target attainment even at a MIC of 2 mg/L, where neonates required doses of 6-7 mg/kg/day and older pediatrics required lower daily doses of 4–5 mg/kg/day while maintaining trough gentamicin concentration below the toxicity limit of 1 mg/L. Conclusion: Once daily dosing is a reasonable option in pediatrics that allows target attainment while maintaining trough gentamicin level below the limits of toxicity.

scholarly journals Association between Vancomycin Trough Concentration and Area under the Concentration-Time Curve in Neonates

2014 ◽  
Vol 58 (11) ◽  
pp. 6454-6461 ◽  
Author(s):  
Adam Frymoyer ◽  
Adam L. Hersh ◽  
Mohammed H. El-Komy ◽  
Shabnam Gaskari ◽  
Felice Su ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Serum Creatinine ◽  
Monte Carlo Simulations ◽  
Serum Creatinine Level ◽  
Creatinine Level ◽  
Population Pharmacokinetic ◽  
Time Curve ◽  
Concentration Time ◽  
Vancomycin Trough ◽  
Trough Concentrations

ABSTRACTNational treatment guidelines for invasive methicillin-resistantStaphylococcus aureus(MRSA) infections recommend targeting a vancomycin 24-h area under the concentration-time curve (AUC0–24)-to-MIC ratio of >400. The range of vancomycin trough concentrations that best predicts an AUC0–24of >400 in neonates is not known. This understanding would help clarify target trough concentrations in neonates when treating MRSA. A retrospective chart review from a level III neonatal intensive care unit was performed to identify neonates treated with vancomycin over a 5-year period. Vancomycin concentrations and clinical covariates were utilized to develop a one-compartment population pharmacokinetic model and examine the relationships between trough and AUC0–24in the study neonates. Monte Carlo simulations were performed to examine the effect of dose, postmenstrual age (PMA), and serum creatinine level on trough and AUC0–24achievement. A total of 1,702 vancomycin concentrations from 249 neonates were available for analysis. The median (interquartile range) PMA was 39 weeks (32 to 42 weeks) and weight was 2.9 kg (1.6 to 3.7 kg). Vancomycin clearance was predicted by weight, PMA, and serum creatinine level. At a trough of 10 mg/liter, 89% of the study neonates had an AUC0–24of >400. Monte Carlo simulations demonstrated that troughs ranging from 7 to 11 mg/liter were highly predictive of an AUC0–24of >400 across a range of PMA, serum creatinine levels, and vancomycin doses. However, a trough of ≥10 mg/liter was not readily achieved in most simulated subgroups using routine starting doses. Higher starting doses frequently resulted in troughs of >20 mg/liter. A vancomycin trough of ∼10 mg/liter is likely adequate for most neonates with invasive MRSA infections based on considerations of the AUC0–24. Due to pharmacokinetic and clinical heterogeneity in neonates, consistently achieving this target vancomycin exposure with routine starting doses is difficult. More robust clinical dosing support tools are needed to help clinicians with dose individualization.

scholarly journals In Vivo Pharmacodynamic Target Assessment of Antofloxacin against Streptococcus pneumoniae and Staphylococcus aureus in a Neutropenic Murine Pneumonia Model

2020 ◽  
Vol 64 (12) ◽  
Author(s):  
Yu-Feng Zhou ◽  
Ping Liu ◽  
Shu-He Dai ◽  
Jian Sun ◽  
Ya-Hong Liu ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Streptococcus Pneumoniae ◽  
Free Drug ◽  
Time Curve ◽  
Content Type ◽  
Concentration Time ◽  
Lung Epithelial ◽  
The Mean ◽  
And Staphylococcus Aureus

ABSTRACT We determined in vivo efficacy and target PK/PD exposures of antofloxacin against Streptococcus pneumoniae and Staphylococcus aureus in the murine pneumonia model. The mean plasma free drug area under the concentration-time curve/MIC (fAUC/MIC) targets associated with stasis and 1-log10 and 2-log10 kill effects were 8.93, 19.2, and 48.1, respectively, for S. pneumoniae, whereas they were 30.5, 55.4, and 115.8, respectively, for S. aureus. The fAUC/MIC targets in murine lung epithelial lining fluids (ELF) for the same endpoints were nearly 2-fold higher than those in plasma.

scholarly journals Pharmacokinetics-Pharmacodynamics of Pyrazinamide in a Novel In Vitro Model of Tuberculosis for Sterilizing Effect: a Paradigm for Faster Assessment of New Antituberculosis Drugs

2009 ◽  
Vol 53 (8) ◽  
pp. 3197-3204 ◽  
Author(s):  
Tawanda Gumbo ◽  
Chandima S. W. Siyambalapitiyage Dona ◽  
Claudia Meek ◽  
Richard Leff
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Pharmacokinetic Parameters ◽  
Maximal Effect ◽  
Time Curve ◽  
Time Profiles ◽  
Concentration Time ◽  
Antituberculosis Therapy ◽  
Vitro Model

ABSTRACT There are currently renewed efforts to develop drugs that could shorten the duration of antituberculosis therapy. This is best achieved by optimizing the sterilizing effect. However, the current pathway for the development of new molecules with the potential to have a sterilizing effect is inefficient. We designed an in vitro pharmacokinetic-pharmacodynamic model in which Mycobacterium tuberculosis replicating slowly at pH 5.8 was exposed to pyrazinamide by use of the concentration-time profiles encountered in patients. The sterilizing effect rates and the time to the emergence of drug resistance were examined. Daily pyrazinamide dosing for 28 days accurately achieved (i) the pyrazinamide pharmacokinetic parameters, (ii) the lack of early bactericidal activity, (iii) a sterilizing effect rate of 0.10 log10 CFU/ml per day starting on day 6 of therapy, and (iv) a time to the emergence of resistance of the from 2 to 3 weeks of monotherapy encountered in patients with tuberculosis. Next, dose-scheduling studies were performed. The sterilizing effect was linked to the pyrazinamide ratio of the area under the concentration-time curve from 0 to 24 h (AUC0-24) to the MIC (r 2 = 0.80 to 0.90), with 90% of the maximal effect being achieved by an AUC0-24/MIC of 209.08. Resistance suppression was associated with the percentage of time that the concentration persisted above the MIC (r 2 = 0.73 to 0.91). Monte Carlo simulations of 10,000 patients demonstrated that the currently recommended pyrazinamide doses (15 to 30 mg/kg of body weight/day) achieved the AUC0-24/MIC of 209.08 in the epithelial lining fluid of only 15.1 to 53.3% of patients. Doses of >60 mg/kg per day performed better. Our vitro model for the sterilizing effect, together with Monte Carlo simulations, can be used for the faster identification of the clinical doses that are needed to achieve a sterilizing effect and that can then be studied in clinical trials.

scholarly journals Fosamprenavir plus Ritonavir Increases Plasma Ketoconazole and Ritonavir Exposure, while Amprenavir Exposure Remains Unchanged

2007 ◽  
Vol 51 (8) ◽  
pp. 2982-2984 ◽  
Author(s):  
Mary B. Wire ◽  
Charles H. Ballow ◽  
Julie Borland ◽  
Mark J. Shelton ◽  
Yu Lou ◽  
...  
Keyword(s):  
Steady State ◽  
Healthy Subjects ◽  
Open Label ◽  
Time Curve ◽  
Once Daily ◽  
Open Label Study ◽  
Label Study ◽  
Concentration Time

ABSTRACT Plasma ketoconazole (KETO), amprenavir (APV), and ritonavir (RTV) pharmacokinetics were evaluated in 15 healthy subjects after being treated with KETO at 200 mg once daily (QD), fosamprenavir (FPV)/RTV at 700/100 mg twice daily (BID), and then KETO at 200 mg QD plus FPV/RTV at 700/100 mg BID in this open-label study. The KETO area under the concentration-time curve at steady state was increased 2.69-fold with FPV/RTV. APV exposure was unchanged, and RTV exposure was slightly increased.

scholarly journals Determination of Pharmacodynamic Target Exposures for Rezafungin against Candida tropicalis and Candida dubliniensis in the Neutropenic Mouse Disseminated Candidiasis Model

2019 ◽  
Vol 63 (11) ◽  
Author(s):  
Alexander J. Lepak ◽  
Miao Zhao ◽  
David R. Andes
Keyword(s):  
Candida Tropicalis ◽  
Free Drug ◽  
Candida Dubliniensis ◽  
Time Curve ◽  
Content Type ◽  
Susceptibility Data ◽  
Concentration Time ◽  
Target Exposure ◽  
Human Dose

ABSTRACT Rezafungin (CD101) is a novel echinocandin under development for once-weekly intravenous (i.v.) dosing. We evaluated the pharmacodynamics (PD) of rezafungin against 4 Candida tropicalis and 4 Candida dubliniensis strains, using the neutropenic mouse invasive candidiasis model. The area under the concentration-time curve (AUC)/MIC was a robust predictor of efficacy (R2 = 0.93 and 0.72, respectively). The stasis free-drug 24-h AUC/MIC target exposure for the group ranged from 3 to 25, whereas the 1-log-kill free-drug 24-h AUC/MIC target exposure ranged from 4.3 to 62. These values are similar to those found in previous rezafungin PD studies with other Candida spp. Based on recent surveillance susceptibility data, AUC/MIC targets are likely to be exceeded for >99% of C. tropicalis and C. dubliniensis isolates with the previously studied human dose of 400 mg i.v. once weekly.

scholarly journals Administration of aminoglycosides to hemodialysis patients immediately before dialysis: a new dosing modality.

1997 ◽  
Vol 41 (12) ◽  
pp. 2597-2601 ◽  
Author(s):  
H Matsuo ◽  
J Hayashi ◽  
K Ono ◽  
K Andoh ◽  
Y Andoh ◽  
...  
Keyword(s):  
High Performance ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Cellulose Triacetate ◽  
The Body ◽  
High Rate ◽  
Complete Disappearance ◽  
Time Curve ◽  
Once Daily ◽  
Ethylene Vinyl Alcohol ◽  
Concentration Time

We describe a new modality for administering aminoglycosides to hemodialysis (HD) patients, namely, a modification of the once-daily regimen which consists of administering the aminoglycosides over 60 min by drip infusion just before each HD session, with a preplanned peak concentration being reached at the beginning of the session and then with a rapidly decreasing concentration being achieved by the start of HD. The area under the concentration-time curve (AUC), i.e., the accumulation of the drug in the body, is thus minimized by this modality. Arbekacin (ABK) was given at a dose of 2 mg/kg of body weight to 10 HD patients infected with methicillin-resistant Staphylococcus aureus (MRSA) for 2 weeks (six sessions in total), resulting in the complete disappearance of MRSA in 5 patients. A high rate of elimination of ABK was attained for each patient while the patient was on HD (range, 0.20 to 0.42 h-1; mean 0.28 +/- 0.08 h-1) by using high-performance dialyzers provided with membranes made of either polymethylmethacrylate, cellulose triacetate (CTA), or ethylene vinyl alcohol. The best results were obtained with the CTA membrane, as revealed by the overall mass transfer coefficient (Ko). The AUC in the simulation model for the variation in the serum ABK concentration in this modality was calculated to be 40% of that of the conventional post-HD dosing modality, suggesting that a much higher dose could be administered to HD patients who receive HD thrice weekly (4 h per session), giving, e.g., 4 mg/kg initially and before the HD sessions, when there is an interval of 68 h from HD session to HD session, and giving 2 mg/kg before the other sessions.

scholarly journals Once-Daily Dosing in Dogs Optimizes Daptomycin Safety

2000 ◽  
Vol 44 (11) ◽  
pp. 2948-2953 ◽  
Author(s):  
F. B. Oleson ◽  
C. L. Berman ◽  
J. B. Kirkpatrick ◽  
K. S. Regan ◽  
J.-J. Lai ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Maximum Concentration ◽  
Time Curve ◽  
Once Daily ◽  
Gram Positive Bacteria ◽  
Concentration Time ◽  
Serum Creatine Phosphokinase ◽  
Lower Maximum ◽  
Resistant Strains ◽  
Lipopeptide Antibiotic

ABSTRACT Daptomycin is a novel lipopeptide antibiotic with potent bactericidal activity against most clinically important gram-positive bacteria, including resistant strains. Daptomycin has been shown to have an effect on skeletal muscle. To guide the clinical dosing regimen with the potential for the least effect on skeletal muscle, two studies were conducted with dogs to compare the effects of repeated intravenous administration every 24 h versus every 8 h for 20 days. The data suggest that skeletal-muscle effects were more closely related to the dosing interval than to either the maximum concentration of the drug in plasma or the area under the concentration-time curve. Both increases in serum creatine phosphokinase activity and the incidence of myopathy observed at 25 mg/kg of body weight every 8 h were greater than those observed at 75 mg/kg every 24 h despite the lower maximum concentration of drug in plasma. Similarly, the effects observed at 25 mg/kg every 8 h were greater than those observed at 75 mg/kg every 24 h at approximately the same area under the concentration-time curve from 0 to 24 h. Once-daily administration appeared to minimize the potential for daptomycin-related skeletal-muscle effects, possibly by allowing for more time between doses for repair of subclinical effects. Thus, these studies with dogs suggest that once-daily dosing of daptomycin in humans should have the potential to minimize skeletal-muscle effects. In fact, interim results of ongoing clinical trials, which have focused on once-daily dosing, appear to be consistent with this conclusion.

scholarly journals Pharmacokinetics of Tedizolid in an Obese Patient after Bariatric Surgery

2018 ◽  
Vol 62 (4) ◽  
Author(s):  
Matthieu Grégoire ◽  
Julia Brochard Libois ◽  
Denis Waast ◽  
Benjamin Gaborit ◽  
Marc Dauty ◽  
...  
Keyword(s):  
Bariatric Surgery ◽  
Bypass Surgery ◽  
Obese Woman ◽  
Total Plasma ◽  
Time Curve ◽  
Once Daily ◽  
Content Type ◽  
Concentration Time ◽  
Target Ratio ◽  
Plasma Peak

ABSTRACT An obese woman was treated with oral tedizolid 200 mg once daily for pseudoarthrosis 10 years after Roux-en-Y bypass surgery. Total plasma peak concentration was 2.12 mg/liter 3 h after intake, and area under the concentration-time curve from 0 to 24 h (AUC 0–24 ) was 28.3 mg/liter · h. The AUC 0–24 /MIC ratio for unbound concentrations and for sensitive Staphylococcus and Streptococcus strains was ≥10.8, higher than the target ratio of 3. These results support the use of tedizolid without adjustment after bariatric surgery.

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