Pharmacodynamics of Isavuconazole in a DynamicIn VitroModel of Invasive Pulmonary Aspergillosis

ABSTRACTIsavuconazonium sulfate is a novel triazole prodrug that has been recently approved for the treatment of invasive aspergillosis by the FDA. The active moiety (isavuconazole) has a broad spectrum of activity against many pathogenic fungi. This study utilized a dynamicin vitromodel of the human alveolus to describe the pharmacodynamics of isavuconazole against two wild-type and two previously defined azole-resistant isolates ofAspergillus fumigatus. A human-like concentration-time profile for isavuconazole was generated. MICs were determined using CLSI and EUCAST methodologies. Galactomannan was used as a measure of fungal burden. Target values for the area under the concentration-time curve (AUC)/MIC were calculated using a population pharmacokinetics-pharmacodynamics (PK-PD) mathematical model. Isolates with higher MICs required higher AUCs in order to achieve maximal suppression of galactomannan. The AUC/MIC targets necessary to achieve 90% probability of galactomannan suppression of <1 were 11.40 and 11.20 for EUCAST and CLSI, respectively.

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Pharmacological Basis of CD101 Efficacy: Exposure Shape Matters

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00758-17 ◽

2017 ◽

Vol 61 (11) ◽

Cited By ~ 12

Author(s):

Elizabeth A. Lakota ◽

Justin C. Bader ◽

Voon Ong ◽

Ken Bartizal ◽

Lynn Miesel ◽

...

Keyword(s):

Time Course ◽

Fungicidal Activity ◽

Control Group ◽

Time Curve ◽

Content Type ◽

Treatment Groups ◽

Concentration Time ◽

Treatment Control Group ◽

Pharmacological Basis

ABSTRACT CD101 is a novel echinocandin with concentration-dependent fungicidal activity in vitro and a long half-life (∼133 h in humans, ∼70 to 80 h in mice). Given these characteristics, it is likely that the shape of the CD101 exposure (i.e., the time course of CD101 concentrations) influences efficacy. To test this hypothesis, doses which produce the same total area under the concentration-time curve (AUC) were administered to groups of neutropenic ICR mice infected with Candida albicans R303 using three different schedules. A total CD101 dose of 2 mg/kg was administered as a single intravenous (i.v.) dose or in equal divided doses of either 1 mg/kg twice weekly or 0.29 mg/kg/day over 7 days. The studies were performed using a murine disseminated candidiasis model. Animals were euthanized at 168 h following the start of treatment. Fungi grew well in the no-treatment control group and showed variable changes in fungal density in the treatment groups. When the CD101 AUC from 0 to 168 h (AUC0–168) was administered as a single dose, a >2 log10 CFU reduction from the baseline at 168 h was observed. When twice-weekly and daily regimens with similar AUC values were administered, net fungal stasis and a >1 log10 CFU increase from the baseline were observed, respectively. These data support the hypothesis that the shape of the CD101 AUC influences efficacy. Thus, CD101 administered once per week demonstrated a greater degree of fungal killing than the same dose divided into twice-weekly or daily regimens.

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Development of a Physiologically Based Pharmacokinetic Model for Prediction of Ethanol Concentration-Time Profile in Different Organs

Alcohol and Alcoholism ◽

10.1093/alcalc/agaa129 ◽

2020 ◽

Author(s):

Armin Sadighi ◽

Lorenzo Leggio ◽

Fatemeh Akhlaghi

Keyword(s):

Pbpk Model ◽

Organ Damage ◽

Time Profile ◽

Sensitivity Analyses ◽

Pbpk Modeling ◽

Time Curve ◽

Physiologically Based Pharmacokinetic ◽

Concentration Time ◽

Physiologically Based

Abstract Aims A physiologically based pharmacokinetic (PBPK) modeling approach was used to simulate the concentration-time profile of ethanol (EtOH) in stomach, duodenum, plasma and other tissues upon consumption of beer and whiskey under fasted and fed conditions. Methods A full PBPK model was developed for EtOH using the advanced dissolution, absorption and metabolism (ADAM) model fully integrated into the Simcyp Simulator® 15 (Simcyp Ltd., Sheffield, UK). The prediction performance of the developed model was verified and the EtOH concentration-time profile in different organs was predicted. Results Simcyp simulation showed ≤ 2-fold difference in values of EtOH area under the concentration-time curve (AUC) in stomach and duodenum as compared to the observed values. Moreover, the simulated EtOH maximum concentration (Cmax), time to reach Cmax (Tmax) and AUC in plasma were comparable to the observed values. We showed that liver is exposed to the highest EtOH concentration, faster than other organs (Cmax = 839.50 mg/L and Tmax = 0.53 h), while brain exposure of EtOH (AUC = 1139.43 mg·h/L) is the highest among all other organs. Sensitivity analyses (SAs) showed direct proportion of EtOH rate and extent of absorption with administered EtOH dose and inverse relationship with gastric emptying time (GE) and steady-state volume of distribution (Vss). Conclusions The current PBPK model approach might help with designing in vitro experiments in the area of alcohol organ damage or alcohol-drug interaction studies.

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Pharmacokinetics of Telavancin at Fixed Doses in Normal-Body-Weight and Obese (Classes I, II, and III) Adult Subjects

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02475-17 ◽

2018 ◽

Vol 62 (4) ◽

Cited By ~ 2

Author(s):

Kristen L. Bunnell ◽

Manjunath P. Pai ◽

Monica Sikka ◽

Susan C. Bleasdale ◽

Eric Wenzler ◽

...

Keyword(s):

Body Weight ◽

Time Profile ◽

Primary Objective ◽

Fixed Dose ◽

Target Area ◽

Obese Patients ◽

Time Curve ◽

Content Type ◽

Time Zero ◽

Concentration Time

ABSTRACT A recommended total-body-weight (TBW) dosing strategy for telavancin may not be optimal in obese patients. The primary objective of this study was to characterize and compare the pharmacokinetics (PK) of telavancin across four body size groups: normal to overweight and obese classes I, II, and III. Healthy adult subjects ( n = 32) received a single, weight-stratified, fixed dose of 500 mg ( n = 4), 750 mg ( n = 8), or 1,000 mg ( n = 20) of telavancin. Noncompartmental PK analyses revealed that subjects with a body mass index (BMI) of ≥40 kg/m 2 had a higher volume of distribution (16.24 ± 2.7 liters) than subjects with a BMI of <30 kg/m 2 (11.71 ± 2.6 liters). The observed area under the concentration-time curve from time zero to infinity (AUC 0–∞ ) ranged from 338.1 to 867.3 mg · h/liter, with the lowest exposures being in subjects who received 500 mg. AUC 0–∞ values were similar among obese subjects who received 1,000 mg. A two-compartment population PK model best described the plasma concentration-time profile of telavancin when adjusted body weight (ABW) was included as a predictive covariate. Fixed doses of 750 mg and 1,000 mg had similar target attainment probabilities for efficacy as doses of 10 mg/kg of body weight based on ABW and TBW, respectively. However, the probability of achieving a target area under the concentration-time curve from time zero to 24 h of ≥763 mg · h/liter in association with acute kidney injury was highest (19.7%) with TBW-simulated dosing and lowest (0.4%) at the 750-mg dose. These results suggest that a fixed dose of 750 mg is a safe and effective alternative to telavancin doses based on TBW or ABW for the treatment of obese patients with normal renal function and Staphylococcus aureus infections. (This study has been registered at ClinicalTrials.gov under identifier NCT02753855.)

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Pharmacokinetic-Pharmacodynamic Characterization of Omadacycline against Haemophilus influenzae Using a One-Compartment In Vitro Infection Model

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02265-19 ◽

2020 ◽

Vol 64 (6) ◽

Cited By ~ 2

Author(s):

Brian D. VanScoy ◽

Elizabeth A. Lakota ◽

Haley Conde ◽

Jennifer McCauley ◽

Lawrence Friedrich ◽

...

Keyword(s):

Haemophilus Influenzae ◽

Antimicrobial Agents ◽

Nonlinear Least Squares ◽

Infection Model ◽

Least Squares Regression ◽

Total Drug ◽

Time Curve ◽

Content Type ◽

Concentration Time

ABSTRACT Omadacycline is a novel aminomethylcycline with activity against Gram-positive and -negative organisms, including Haemophilus influenzae, which is one of the leading causes of community-acquired bacterial pneumonia (CABP). The evaluation of antimicrobial agents against H. influenzae using standard murine infection models is challenging due to the low pathogenicity of this species in mice. Therefore, 24-h dose-ranging studies using a one-compartment in vitro infection model were undertaken with the goal of characterizing the magnitude of the ratio of the area under the concentration-time curve (AUC) to the MIC (AUC/MIC ratio) associated with efficacy for a panel of five H. influenzae isolates. These five isolates, for which MIC values were 1 or 2 mg/liter, were exposed to omadacycline total-drug epithelial lining fluid (ELF) concentration-time profiles based on those observed in healthy volunteers following intravenous omadacycline administration. Relationships between change in log10 CFU/ml from baseline at 24 h and the total-drug ELF AUC/MIC ratios for each isolate and for the isolates pooled were evaluated using Hill-type models and nonlinear least-squares regression. As evidenced by the high coefficients of determination (r2) of 0.88 to 0.98, total-drug ELF AUC/MIC ratio described the data well for each isolate and the isolates pooled. The median total-drug ELF AUC/MIC ratios associated with net bacterial stasis and 1- and 2-log10 CFU/ml reductions from baseline at 24 h were 6.91, 8.91, and 11.1, respectively. These data were useful to support the omadacycline dosing regimens selected for the treatment of patients with CABP, as well as susceptibility breakpoints for H. influenzae.

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Toward Harmonization of Voriconazole CLSI and EUCAST Breakpoints for Candida albicans Using a Validated In Vitro Pharmacokinetic/Pharmacodynamic Model

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00170-20 ◽

2020 ◽

Vol 64 (6) ◽

Author(s):

Maria-Ioanna Beredaki ◽

Panagiota-Christina Georgiou ◽

Maria Siopi ◽

Lamprini Kanioura ◽

David Andes ◽

...

Keyword(s):

Candida Albicans ◽

Simulation Analysis ◽

Maximal Activity ◽

Wild Type ◽

Time Curve ◽

Unbound Fraction ◽

Content Type ◽

Interval Probability

ABSTRACT CLSI and EUCAST susceptibility breakpoints for voriconazole and Candida albicans differ by one dilution (≤0.125 and ≤0.06 mg/liter, respectively) whereas the epidemiological cutoff values for EUCAST (ECOFF) and CLSI (ECV) are the same (0.03 mg/liter). We therefore determined the pharmacokinetic/pharmacodynamic (PK/PD) breakpoints of voriconazole against C. albicans for both methodologies with an in vitro PK/PD model, which was validated using existing animal PK/PD data. Four clinical wild-type and non-wild-type C. albicans isolates (voriconazole MICs, 0.008 to 0.125 mg/liter) were tested in an in vitro PK/PD model. For validation purposes, mouse PK were simulated and in vitro PD were compared with in vivo outcomes. Human PK were simulated, and the exposure-effect relationship area under the concentration-time curve for the free, unbound fraction of a drug from 0 to 24 h (fAUC0–24)/MIC was described for EUCAST and CLSI 24/48-h methods. PK/PD breakpoints were determined using the fAUC0–24/MIC associated with half-maximal activity (EI50) and Monte Carlo simulation analysis. The in vitro 24-h PD EI50 values of voriconazole against C. albicans were 2.5 to 5 (1.5 to 17) fAUC/MIC. However, the 72-h PD were higher at 133 (51 to 347) fAUC/MIC for EUCAST and 94 (35 to 252) fAUC/MIC for CLSI. The mean (95% confidence interval) probability of target attainment (PTA) was 100% (95 to 100%), 97% (72 to 100%), 83% (35 to 99%), and 49% (8 to 91%) for EUCAST and 100% (97 to 100%), 99% (85 to 100%), 91% (52 to 100%), and 68% (17 to 96%) for CLSI for MICs of 0.03, 0.06, 0.125, and 0.25 mg/liter, respectively. Significantly, >95% PTA values were found for EUCAST/CLSI MICs of ≤0.03 mg/liter. For MICs of 0.06 to 0.125 mg/liter, trough levels 1 to 4 mg/liter would be required to attain the PK/PD target. A PK/PD breakpoint of C. albicans voriconazole at the ECOFF/ECV of 0.03 mg/liter was determined for both the EUCAST and CLSI methods, indicating the need for breakpoint harmonization for the reference methodologies.

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Comparative Pharmacodynamics of Posaconazole in Neutropenic Murine Models of Invasive Pulmonary Aspergillosis and Mucormycosis

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.03569-14 ◽

2014 ◽

Vol 58 (11) ◽

pp. 6767-6772 ◽

Cited By ~ 26

Author(s):

Russell E. Lewis ◽

Nathaniel D. Albert ◽

Dimitrios P. Kontoyiannis

Keyword(s):

Rhizopus Oryzae ◽

Invasive Pulmonary Aspergillosis ◽

High Dose ◽

Murine Models ◽

Total Drug ◽

Pulmonary Aspergillosis ◽

Time Curve ◽

Content Type ◽

Pulmonary Mucormycosis ◽

Concentration Time

ABSTRACTWe used two established neutropenic murine models of pulmonary aspergillosis and mucormycosis to explore the association between the posaconazole area under the concentration-time curve (AUC)-to-MIC ratio (AUC/MIC) and treatment outcome. Posaconazole serum pharmacokinetics were verified in infected mice to ensure that the studied doses reflected human exposures with the oral suspension, delayed-release tablet, and intravenous formulations of posaconazole. Sinopulmonary infections were then induced in groups of neutropenic mice withAspergillus fumigatusstrain 293 (posaconazole MIC, 0.5 mg/liter) orRhizopus oryzaestrain 969 (posaconazole MIC, 2 mg/liter) and treated with escalating daily dosages of oral posaconazole, which was designed to achieve AUCs ranging from 1.10 to 392 mg · h/liter. After 5 days of treatment, lung fungal burden was analyzed by quantitative real-time PCR. The relationships of the total drug AUC/MIC and the treatment response were similar in both models, with 90% effective concentrations (EC90s) corresponding to an AUC/MIC threshold of 76 (95% confidence interval [CI], 46 to 102) for strain 293 versus 87 (95% CI, 66 to 101) for strain 969. Using a provisional AUC/MIC target of >100, these exposures correlated with minimum serum posaconazole concentrations (Cmins) of 1.25 mg/liter for strain 293 and 4.0 mg/liter for strain 969. The addition of deferasirox, but not liposomal amphotericin or caspofungin, improved the activity of a suboptimal posaconazole regimen (AUC/MIC, 33) in animals with pulmonary mucormycosis. However, no combination was as effective as the high-dose posaconazole monotherapy regimen (AUC/MIC, 184). Our analysis suggests that posaconazole pharmacodynamics are similar forA. fumigatusandR. oryzaewhen indexed to pathogen MICs.

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Comparative Efficacies of Tedizolid Phosphate, Vancomycin, and Daptomycin in a Rabbit Model of Methicillin-Resistant Staphylococcus aureus Endocarditis

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.04376-14 ◽

2015 ◽

Vol 59 (6) ◽

pp. 3252-3256 ◽

Cited By ~ 13

Author(s):

Liana C. Chan ◽

Li Basuino ◽

Etyene C. Dip ◽

Henry F. Chambers

Keyword(s):

Staphylococcus Aureus ◽

Rabbit Model ◽

Time Curve ◽

Methicillin Resistant ◽

Content Type ◽

Treatment Groups ◽

Concentration Time ◽

Dose Ranging

ABSTRACTTedizolid, the active component of the prodrug tedizolid phosphate, is a novel oxazolidinone that is approximately 4 times more active by weight than linezolid againstStaphylococcus aureusin vitro. Thein vivoefficacy of tedizolid phosphate (15 mg/kg body weight intravenous [i.v.] twice a day [b.i.d.]) was compared to those of vancomycin (30 mg/kg i.v. b.i.d.) and daptomycin (18 mg/kg i.v. once a day [q.d.]) in a rabbit model of aortic valve endocarditis (AVE) caused by methicillin-resistantS. aureusstrain COL (infection inoculum of 107CFU). Median vegetation titers of daptomycin-treated rabbits were significantly lower than those of rabbits treated with tedizolid phosphate (15 mg/kg b.i.d.) (P= 0.016), whereas titers for vancomycin-treated compared to tedizolid-treated rabbits were not different (P= 0.984). The numbers of organisms in spleen and kidney tissues were similar for all treatment groups. A dose-ranging experiment was performed with tedizolid phosphate (2, 4, and 8 mg/kg b.i.d.) compared to vancomycin (30 mg/kg b.i.d.), using a higher infecting inoculum (108CFU) to determine the lowest efficacious dose of tedizolid phosphate. Tedizolid phosphate (2 mg/kg) (equivalent to 60% of the area under the concentration-time curve from 0 to 24 h (AUC0–24) for the human 200-mg dose approved by the U.S. Food and Drug Administration) was not efficacious. Tedizolid phosphate at 4 mg/kg (equivalent to 75% of the AUC0–24for the human 400-mg dose) and 8 mg/kg produced lower vegetation titers than the control, but neither was as efficacious as vancomycin.

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The Small GTPase RacA Mediates Intracellular Reactive Oxygen Species Production, Polarized Growth, and Virulence in the Human Fungal Pathogen Aspergillus fumigatus

Eukaryotic Cell ◽

10.1128/ec.00288-10 ◽

2010 ◽

Vol 10 (2) ◽

pp. 174-186 ◽

Cited By ~ 31

Author(s):

Haiyan Li ◽

Bridget M. Barker ◽

Nora Grahl ◽

Srisombat Puttikamonkul ◽

Jeremey D. Bell ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Aspergillus Fumigatus ◽

Invasive Pulmonary Aspergillosis ◽

Reactive Oxygen ◽

Small Gtpase ◽

Oxygen Species ◽

Wild Type ◽

Content Type ◽

Diphenylene Iodonium

ABSTRACTAspergillus fumigatusis the predominant mold pathogen in immunocompromised patients. In this study, we present the first characterization of the small GTPase RacA inA. fumigatus. To gain insight into the function ofracAin the growth and pathogenesis ofA. fumigatus, we constructed a strain that lacks a functionalracAgene. The ΔracAstrain showed significant morphological defects, including a reduced growth rate and abnormal conidiogenesis on glucose minimal medium. In the ΔracAstrain, apical dominance in the leading hyphae is lost and, instead, multiple axes of polarity emerge. Intriguingly, superoxide production at the hyphal tips was reduced by 25% in the ΔracAstrain. Treatment of wild-type hyphae with diphenylene iodonium, an inhibitor of NADPH oxidase, resulted in phenotypes similar to that of the ΔracAstrain. These data suggest that ΔracAstrain phenotypes may be due to a reduction or alteration in the production of reactive oxygen species. Most surprisingly, despite these developmental and growth abnormalities, the ΔracAstrain retained at least wild-type virulence in both an insect model and two immunologically distinct murine models of invasive pulmonary aspergillosis. These results demonstrate thatin vitrogrowth phenotypes do not always correlate within vivovirulence and raise intriguing questions about the role of RacA inAspergillusvirulence.

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Posaconazole Pharmacodynamic Target Determination against Wild-Type andCyp51Mutant Isolates of Aspergillus fumigatus in anIn VivoModel of Invasive Pulmonary Aspergillosis

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01279-12 ◽

2012 ◽

Vol 57 (1) ◽

pp. 579-585 ◽

Cited By ~ 42

Author(s):

Alexander J. Lepak ◽

Karen Marchillo ◽

Jaimie VanHecker ◽

David R. Andes

Keyword(s):

Dose Range ◽

Invasive Pulmonary Aspergillosis ◽

Free Drug ◽

Lung Homogenate ◽

Study Endpoint ◽

Pharmacokinetic Data ◽

Wild Type ◽

Pulmonary Aspergillosis ◽

Time Curve ◽

Content Type

ABSTRACTInvasive pulmonary aspergillosis (IPA) is a devastating disease of immunocompromised patients. Pharmacodynamic (PD) examination of antifungal drug therapy in IPA is one strategy that may improve outcomes. The current study explored the PD target of posaconazole in an immunocompromised murine model of IPA against 10A. fumigatusisolates, including 4Cyp51wild-type isolates and 6 isolates carryingCyp51mutations conferring azole resistance. The posaconazole MIC range was 0.25 to 8 mg/liter. Following infection, mice were given 0.156 to 160 mg/kg of body weight of oral posaconazole daily for 7 days. Efficacy was assessed by quantitative PCR (qPCR) of lung homogenate and survival. At the start of therapy, mice had 5.59 ± 0.19 log10Aspergillusconidial equivalents (CE)/ml of lung homogenate, which increased to 7.11 ± 0.29 log10CE/ml of lung homogenate in untreated animals. The infection was uniformly lethal prior to the study endpoint in control mice. A Hill-type dose response function was used to model the relationship between posaconazole free drug area under the concentration-time curve (AUC)/MIC and qPCR lung burden. The static dose range was 1.09 to 51.9 mg/kg/24 h. The free drug AUC/MIC PD target was 1.09 ± 0.63 for the group of strains. The 1-log kill free drug AUC/MIC was 2.07 ± 1.02. The PD target was not significantly different for the wild-type and mutant organism groups. Mortality mirrored qPCR results, with the greatest improvement in survival noted at the same dosing regimens that produced static or cidal activity. Consideration of human pharmacokinetic data and the current static dose PD target would predict a clinical MIC threshold of 0.25 to 0.5 mg/liter.

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Pharmacokinetic-Pharmacodynamic Target Attainment Analyses To Support Dose Selection for ME1100, an Arbekacin Inhalation Solution

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02367-19 ◽

2020 ◽

Vol 64 (10) ◽

Author(s):

Sujata M. Bhavnani ◽

Jeffrey P. Hammel ◽

Elizabeth A. Lakota ◽

M. Courtney Safir ◽

Brian D. VanScoy ◽

...

Keyword(s):

Compartment Model ◽

Simulated Patients ◽

Population Pharmacokinetic ◽

Total Drug ◽

Target Attainment ◽

Time Curve ◽

Content Type ◽

Concentration Time

ABSTRACT ME1100 (arbekacin inhalation solution) is an inhaled aminoglycoside that is being developed to treat patients with hospital-acquired and ventilator-associated bacterial pneumonia (HABP and VABP, respectively). Pharmacokinetic-pharmacodynamic (PK-PD) target attainment analyses were undertaken to evaluate ME1100 regimens for the treatment of patients with HABP/VABP. The data used included a population pharmacokinetic (PPK) 4-compartment model with 1st-order elimination, nonclinical PK-PD targets from one-compartment in vitro and/or in vivo infection models, and in vitro surveillance data. Using the PPK model, total-drug epithelial lining fluid (ELF) concentration-time profiles were generated for simulated patients with varying creatinine clearance (CLcr) (ml/min/1.73 m2) values. Percent probabilities of PK-PD target attainment by MIC were determined based on the ratio of total-drug ELF area under the concentration-time curve (AUC) to MIC (AUC/MIC ratio) targets associated with 1- and 2-log10 CFU reductions from baseline for Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus. Percent probabilities of PKPD target attainment based on PK-PD targets for a 1-log10 CFU reduction from baseline at MIC values above the MIC90 value for K. pneumoniae (8 μg/ml), P. aeruginosa (4 μg/ml), and S. aureus (0.5 μg/ml) were ≥99.8% for ME1100 600 mg twice daily (BID) in simulated patients with CLcr values >80 to ≤120 ml/min/1.73 m2. ME1100 600 mg BID, 450 mg BID, and 600 mg once daily in simulated patients with CLcr values >50 to ≤80, >30 to ≤50, and 0 to ≤30 ml/min/1.73 m2, respectively, provided arbekacin exposures that best matched those for 600 mg BID in simulated patients with normal renal function. These data provide support for ME1100 as a treatment for patients with HABP/VABP.

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