Population Pharmacokinetic Analyses for Omadacycline Using Phase 1 and 3 Data.
ABSTRACT: Omadacycline, a novel aminomethylcycline antibiotic with activity against Gram-positive and -negative organisms, including tetracycline-resistant pathogens, received FDA approval in October 2018 for the treatment of patients with acute bacterial skin and skin structure infections (ABSSSI) and community-acquired bacterial pneumonia (CABP). A previously developed population pharmacokinetic (PK) model based on phase 1 intravenous and oral PK data was refined using data from infected patients. Data from 10 phase 1 studies used to develop the previous model were pooled with data from three additional phase 1 studies, a phase 1b uncomplicated urinary tract infection study, one phase 3 CABP study, and two phase 3 ABSSSI studies. The final population PK model was a three-compartment model with first-order absorption using transit compartments to account for absorption delay following oral dosing and first-order elimination. Epithelial lining fluid (ELF) concentrations were modeled as a subcompartment of the first peripheral compartment. A food effect on oral bioavailability was included in the model. Sex was the only significant covariate identified, with 15.6% lower clearance for females than males. Goodness-of-fit diagnostics indicated a precise and unbiased fit to the data. The final model, which was robust in its ability to predict plasma and ELF exposures following omadacycline administration, was also able to predict the central tendency and variability in concentration-time profiles using an external phase 3 ABSSSI data set. A population PK model, which described omadacycline PK in healthy subjects and infected patients, was developed and subsequently used to support pharmacokinetic-pharmacodynamic (PK-PD) and PK-PD target attainment assessments.
Project description:Solithromycin is a fluoroketolide antibiotic under investigation for community-acquired bacterial pneumonia (CABP). We developed a whole-body physiologically based pharmacokinetic (PBPK) model for solithromycin in adults using PK-Sim and MoBi version 6.2, which incorporated time-dependent CYP3A4 auto-inhibition. The model was developed and evaluated using plasma and epithelial lining fluid (ELF) concentration data from 100 healthy subjects and 22 patients with CABP (1,966 plasma, 30 ELF samples). We performed population simulations and calculated the number of observations falling outside the 90% prediction interval. For the oral regimen (800 mg on day 1 and 400 mg daily on days 2-5) that was evaluated in phase III studies, 11% and 23% of observations from healthy adults fell outside the 90% prediction interval for plasma and ELF, respectively. This regimen should be effective because ?97% of simulated adults achieved area under the concentration vs. time curve (AUC) to minimum inhibitory concentration ratios associated with a log10 colony forming unit reduction in ELF.
Project description:OBJECTIVES:Lefamulin is a semi-synthetic intravenous (iv) and oral pleuromutilin antibiotic active against community-acquired bacterial pneumonia (CABP) pathogens. Pharmacokinetic/pharmacodynamic (PK/PD) target attainment analyses were carried out to evaluate lefamulin 150 mg iv q12h and 600 mg orally q12h under fed and fasted conditions for the treatment of patients with CABP. METHODS:The analyses undertaken used a population PK model based on Phase 1 PK data, non-clinical PK/PD targets for efficacy and in vitro surveillance data for Streptococcus pneumoniae (SP) and Staphylococcus aureus (SA), and Monte Carlo simulation. Percentage probabilities of PK/PD target attainment by MIC on day 1 were determined using median total-drug epithelial lining fluid (ELF) and free-drug plasma AUC:MIC ratio targets associated with 1 and 2 log10 cfu reductions from baseline. RESULTS:Percentage probabilities of attaining the total-drug ELF AUC:MIC ratio target for a 1 log10 cfu reduction from baseline for SP were ≥99.2% at the MIC90 of 0.12 mg/L and 96.7%, 82.1% and 96.3% for iv and oral dosing regimens under fed and fasted conditions, respectively, at the MIC99 of 0.25 mg/L. Percentage probabilities of attaining the free-drug plasma AUC:MIC target for the same endpoint at the SP MIC99 were 100% for each regimen. For the SA MIC90 of 0.12 mg/L and AUC:MIC ratio targets for the same endpoint, percentage probabilities were 92.7%-100% for iv and oral dosing regimens. CONCLUSIONS:These data provide support for lefamulin 150 mg iv q12h and 600 mg orally q12h for the treatment of patients with CABP and suggest that doses may not need to be taken under fasted conditions.
Project description:Many antibiotics require dose adjustments in patients with renal impairment and/or in those undergoing hemodialysis. Omadacycline, the first aminomethylcycline antibiotic in late-stage clinical development, displays activity against a broad spectrum of bacterial pathogens, including drug-resistant strains. Data from completed phase 3 studies of omadacycline for the treatment of acute bacterial skin and skin structure infections (ABSSSI) and community-acquired bacterial pneumonia (CABP) showed intravenous (i.v.) to once-daily oral omadacycline to be clinically effective and well tolerated. To determine if the dosing of omadacycline should be adjusted in patients with impaired renal function, a phase 1 study examining the pharmacokinetics (PK) and safety of i.v. omadacycline (100 mg) was conducted in subjects with end-stage renal disease (ESRD) on stable hemodialysis (n = 8) and in matched healthy subjects (n = 8). i.v. administration of omadacycline produced similar plasma concentration-time profiles in subjects with ESRD and healthy subjects. Further, in subjects with ESRD, similar values of the PK parameters were observed when omadacycline was administered i.v. after or before dialysis. The mean area under the concentration-time curve from time zero extrapolated to infinity in plasma was 10.30 μg · h/ml when omadacycline was administered to ESRD subjects after dialysis, 10.20 μg · h/ml when omadacycline was administered to ESRD subjects before dialysis, and 9.76 μg · h/ml when omadacycline was administered to healthy subjects. The mean maximum observed concentration of omadacycline in plasma in ESRD subjects was 1.88 μg/ml when it was administered after dialysis and 2.33 μg/ml when it was administered before dialysis, and in healthy subjects it was 1.92 μg/ml. The 100-mg i.v. dose of omadacycline was generally safe and well tolerated in both ESRD and healthy subjects. This study demonstrates that no dose adjustment is necessary for omadacycline in patients with impaired renal function or on days when patients are receiving hemodialysis.
Project description:Background:Omadacycline is an oral and intravenous (IV) once-daily aminomethylcycline antibiotic that was recently approved by the US Food and Drug Administration for the treatment of patients with acute bacterial skin and skin structure infections (ABSSSI). In 2 phase 3 clinical trials, IV-to-oral switch and oral-only administration of omadacycline achieved the primary end points of noninferiority compared with linezolid in treating patients with ABSSSI. Objective:To estimate the potential cost-savings with bioequivalent IV-to-oral antibiotics, such as omadacycline, compared with the standard of care with IV vancomycin by avoiding hospitalizations and reducing hospital stays in patients presenting from the emergency department for ABSSSI treatment. Methods:We used hospital avoidance models to examine the potential cost-savings of managing patients with ABSSSI and no or limited comorbidities and without life-threatening conditions by using omadacycline in the outpatient setting compared with the current standard of care. Early hospital discharge models were used to evaluate the hospital stay reduction that would be required to be achieved with omadacycline treatment relative to IV vancomycin to confer cost-savings compared with standard of care among patients with ABSSSI and ?2 comorbidities but no life-threatening conditions. Results:In the hospital stay avoidance models, cost-savings may be realized by using therapeutically bioequivalent IV-to-oral antibiotics, such as omadacycline, compared with inpatient treatment with IV vancomycin. Based on a sensitivity analysis, further savings could be possible with outpatient administration of omadacycline, even if 20% of omadacycline outpatients were subsequently admitted and incurred the full inpatient cost, with no reimbursement penalties. Of more than 300 patients, only 1 was admitted to the hospital after a full course of omadacycline in the oral-only clinical trial. In the early hospital discharge models, the maximum cost-minimizing daily expense of omadacycline varied from $173 to $936, depending on the presence of active comorbidities or systemic symptoms, hospital stay reduction, and model perspective. Conclusion:These results suggest that the targeted use of antibiotics with bioequivalent IV-to-oral formulations, such as omadacycline, for select patients with ABSSSI may lead to cost-savings compared with inpatient IV vancomycin treatment by shifting care to the outpatient setting or by facilitating earlier hospital discharge among hospitalized patients.
Project description: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 (r 2) 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.
Project description:Background:Omadacycline is an oral and intravenous (IV) once-daily aminomethylcycline antibiotic that is approved in the United States for the treatment of adults with acute bacterial skin and skin structure infections (ABSSSI). It has broad-spectrum activity against common causative pathogens of ABSSSI, including methicillin-resistant Staphylococcus aureus. Omadacycline has been shown to be noninferior to linezolid for the treatment of adults with ABSSSI across 2 phase 3 clinical trials. To date, no studies have assessed the budget impact for omadacycline in the treatment of ABSSSI. Objectives:To estimate the potential budget impact of introducing omadacycline as a treatment option in patients who present to the emergency department (ED) with ABSSSI from the hospital perspective (Medicare payer) in the United States. The ED's and observation units were assumed to be hospital-owned. Methods:The base case of this decision model-based analysis was conducted from the perspective of a hospital for a theoretical cohort of 1 million covered Medicare members over a 3-year time horizon. Scenario analyses included the economic impact of (1) shifting inpatient care to the outpatient setting with omadacycline and (2) reducing hospital length of stay (LOS) among hospitalized patients with omadacycline IV to oral therapy relative to the current inpatient standard of care. Costs are presented in 2017 US dollars with no adjustments for inflation, based on the cost model estimates. Results:The annual total incremental cost following the introduction of omadacycline as a treatment of ABSSSI was $11,168, $39,918, and $88,777 in years 1, 2, and 3, respectively. The incremental cost per member treated (cost per case) rose by $0.49, $1.74, and $3.86 over 3 years. Reducing hospital LOS by 1 day among hospitalized patients with omadacycline resulted in incremental costs of $4311, $15,231, and $33,919 in years 1, 2, and 3, respectively. Under the assumption that patients may be discharged sooner when an oral formulation of the same drug with which they are being treated is available, reducing hospital LOS by 2 days reduced costs by $2546, $9455, and $20,939 in years 1, 2, and 3, respectively. Shifting inpatient care to the outpatient setting with omadacycline reduced costs by $38,777, $139,885, and $310,784 in years 1, 2, and 3, respectively. Conclusion:This hypothetical, model-based study determined that omadacycline would result in a modest increase in total cost over 3 years when introduced as a treatment for ABSSSI in adults who present to the ED for their care.
Project description:Background:The most frequently prescribed regimens for the treatment of hospitalized adults with suspected or documented community-acquired bacterial pneumonia (CABP), an acute bacterial infection of the pulmonary parenchyma, are ceftriaxone plus a macrolide, or a respiratory fluoroquinolone. Although these regimens are consistent with expert guidelines, there are growing concerns regarding their safety and efficacy. Omadacycline is a once-daily antibiotic with oral and intravenous (IV) formulations; it was recently approved in the United States for the treatment of adults with CABP. Objective:To estimate the cost impact of shortening hospital stay or avoiding hospitalization when using a treatment with an IV and an oral formulation, such as omadacycline, versus an IV-only drug regimen, such as ceftriaxone plus a macrolide, in adults with CABP who are not candidates for respiratory fluoroquinolone therapy. Methods:We developed 2 conceptual healthcare decision models to identify potential cost-saving opportunities in hospitalized adults with CABP who receive omadacycline versus ceftriaxone plus a macrolide. The early hospital discharge model examined the cost impact of shifting patients with CABP from inpatient treatment with ceftriaxone plus a macrolide to inpatient IV omadacycline treatment and early hospital discharge with oral omadacycline. The hospital-avoidance model examined the cost impact of omadacycline treatment in the outpatient setting in patients with CABP who have low disease severity. The models defined the upper range of the daily acquisition cost for omadacycline that conferred cost-savings relative to inpatient treatment with ceftriaxone plus a macrolide. Results:In the early hospital discharge model, omadacycline showed cost-savings with a 2-day hospital stay reduction if the daily cost of omadacycline was ≤$836, almost twice its wholesale acquisition cost. In the hospital-avoidance model, the daily omadacycline thresholds that still conferred cost-savings relative to inpatient ceftriaxone plus a macrolide ranged from $1302 to $1334, based on a daily wholesale acquisition cost of $450 for omadacycline, depending on the potential use of the emergency department and an observation unit. CONCLUSION:The study findings show that the targeted use of omadacycline for the treatment of select patient populations with CABP could result in cost-savings relative to inpatient treatment with ceftriaxone plus a macrolide.
Project description:OBJECTIVES:Lefamulin is a semi-synthetic intravenous and oral pleuromutilin antibiotic with activity against pathogens commonly associated with community-acquired bacterial pneumonia. Using data from two Phase 1 studies, a population pharmacokinetics (PPK) model for lefamulin in plasma and epithelial lining fluid (ELF) was constructed. METHODS:Plasma pharmacokinetic (PK) data from a crossover, bioavailability, food-effect study and plasma and ELF PK data from a tissue penetration study in normal healthy volunteers were used to construct a PPK model for lefamulin. Model development involved refinement of a previous PPK model for intravenous and oral administration, followed by application of the model to plasma and ELF data from the tissue penetration study. The ELF penetration ratio of lefamulin was determined using model-based simulations. RESULTS:The PPK analysis data set contained 1103 plasma and 12 ELF lefamulin concentrations from 32 subjects. A three-compartment model with non-linear protein binding and two parallel absorption processes provided precise and unbiased estimated plasma concentration-time profiles. The absorption rate was slower and bioavailability was decreased after a high-fat/high-calorie meal. ELF data were well described using first-order rate constants into and out of the ELF compartment. The median predicted lefamulin total-drug ELF AUC0-24/free-drug plasma AUC0-24 ratio was ∼5:1 after intravenous or oral administration. CONCLUSIONS:The final PPK model allowed precise characterization of plasma and ELF exposures after intravenous and oral administration. The high ELF penetration ratio suggests that the penetration of lefamulin into the effect site is rapid and extensive, irrespective of route of administration.
Project description:Background:Community-acquired bacterial pneumonia (CABP) is an acute, lower respiratory bacterial infection. Despite advances in medical care, CABP remains associated with considerable morbidity, mortality, and healthcare costs; early empiric treatment is recommended by the Infectious Diseases Society of America and by the American Thoracic Society. Omadacycline is an oral and intravenous (IV) once-daily aminomethylcycline antibiotic that is approved in the United States for the treatment of adult patients with CABP. Objective:To estimate the budget impact of introducing omadacycline as a treatment option among patients with suspected or documented CABP from a US hospital perspective. Methods:A budget impact model was developed in Microsoft Excel® 2010. Population, clinical, and cost inputs were based on the available literature, clinical trial data, and real-world evidence databases. Emergency departments and observation units were assumed to be hospital-owned as part of the analyses. Sensitivity analyses assessed the impact of key parameters on the model results, and scenario analyses were explored to analyze the budget impact of reducing length of hospital stay and avoiding hospitalization. Results:The introduction of omadacycline as a treatment resulted in a total budget increase of $20,643 over 3 years. This increase was mainly attributed to treatment acquisition costs. In a scenario where the length of hospital stay was reduced by 1 day (under the assumption that an antibiotic with IV and oral formulations can facilitate earlier discharge from inpatient care), the 3-year total budget decreased to $2384; reducing the hospital stay by 2 days resulted in 3-year cost-savings of $15,875. Shifting inpatient care to the outpatient setting with omadacycline resulted in 3-year cumulative cost-savings of $112,843. Conclusion:This is the first omadacycline budget impact model developed for adult patients with suspected or documented CABP. The model projected a modest budget increase with the introduction of omadacycline, mainly due to treatment acquisition costs.
Project description:BC-3781, a pleuromutilin antimicrobial agent, is being developed for the treatment of patients with acute bacterial skin and skin structure infections (ABSSSI) and community-acquired bacterial pneumonia. Data from a phase 2 study of patients with ABSSSI were used to refine a previous population pharmacokinetic (PK) model and explore potential predictors of PK variability. The previously derived population PK model based on data from three phase 1 studies was applied to sparse sampling data from a phase 2 ABSSSI study and modified as necessary. Covariate analyses were conducted to identify descriptors (e.g., body size, renal function, age) associated with interindividual variability in PK. All population PK analyses were conducted by using Monte Carlo parametric expectation maximization implemented in S-ADAPT 1.5.6. The population PK data set contained 1,167 concentrations from 129 patients; 95% of the patients had 5 or more PK samples (median, 11). The previous population PK model (three-compartment model with first-order elimination and nonlinear protein binding) provided an acceptable and unbiased fit to the data from the 129 patients. Population PK parameters were estimated with acceptable precision; individual clearance values were particularly well estimated (median individual precision of 9.15%). Graphical covariate evaluations showed no relationships between PK and age or renal function but modest relationships between body size and clearance and volume of distribution, which were not statistically significant when included in the population PK model. This population PK model will be useful for subsequent PK-pharmacodynamic analyses and simulations conducted to support phase 3 dose selection. (This study has been registered at ClinicalTrials.gov under registration no. NCT01119105.).