Pharmacokinetic-Pharmacodynamic Target Attainment Analyses as Support for Meropenem-Vaborbactam Dosing Regimens and Susceptibility Breakpoints.

Meropenem-vaborbactam is a fixed-dose beta-lactam/beta-lactamase inhibitor with potent in vitro and in vivo activity against Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacterales. Pharmacokinetic-pharmacodynamic (PK-PD) target attainment analyses were undertaken using population pharmacokinetic models, nonclinical PK-PD targets for efficacy, in vitro surveillance data, and simulation to provide support for 2 g meropenem-2 g vaborbactam every 8 h (q8h) administered as a 3-h intravenous (i.v.) infusion, and dosing regimens adjusted for patients with renal impairment. Simulated patients varying by renal function measure (estimated glomerular filtration rate [eGFR], mL/min/1.73 m2 and absolute eGFR, mL/min) and resembling the clinical trial population (complicated urinary tract infection, including acute pyelonephritis) were generated. The PK-PD targets for meropenem, the percentage of time on day 1 that free-drug plasma concentrations were above the MIC (%T>MIC), and vaborbactam, the ratio of free-drug plasma area under the concentration-time curve (AUC) on day 1 to the MIC (AUC:MIC ratio), were calculated. Percent probabilities of achieving meropenem free-drug plasma %T>MIC and vaborbactam free-drug plasma AUC:MIC ratio targets were assessed. MIC distributions for Enterobacterales, KPC-producing Enterobacterales, and Pseudomonas aeruginosa were considered as part of an algorithm to assess PK-PD target attainment. For assessments of free-drug plasma PK-PD targets associated with a 1-log10 CFU reduction from baseline, percent probabilities of PK-PD target attainment ranged from 81.3 to 100% at meropenem-vaborbactam MIC values of 4 or 8 µg/mL among simulated patients. The results of these PK-PD target attainment analyses provide support for a dosing regimen of 2 g meropenem-2 g vaborbactam q8h administered as a 3-h i.v. infusion, with dosing regimens adjusted for patients with renal impairment and a meropenem-vaborbactam susceptibility breakpoint of ≤8 µg/mL (tested with a fixed vaborbactam concentration of 8 µg/mL) for Enterobacterales and P. aeruginosa based on these dosing regimens.

Population Pharmacokinetics of Meropenem and Vaborbactam Based on Data from Noninfected Subjects and Infected Patients.

Meropenem-vaborbactam is a broad-spectrum carbapenem-beta-lactamase inhibitor combination approved in the United States and Europe to treat patients with complicated urinary tract infections and in Europe for other serious bacterial infections, including hospital-acquired and ventilator-associated pneumonia. Population pharmacokinetic (PK) models were developed to characterize the time course of meropenem and vaborbactam using pooled data from two phase 1 and two phase 3 studies. Multicompartment disposition model structures with linear elimination processes were fit to the data using NONMEM 7.2. Since both drugs are cleared primarily by the kidneys, estimated glomerular filtration rate (eGFR) was evaluated as part of the base structural models. For both agents, a two-compartment model with zero-order input and first-order elimination best described the pharmacokinetic PK data, and a sigmoidal Hill-type equation best described the relationship between renal clearance and eGFR. For meropenem, the following significant covariate relationships were identified: clearance (CL) decreased with increasing age, CL was systematically different in subjects with end-stage renal disease, and all PK parameters increased with increasing weight. For vaborbactam, the following significant covariate relationships were identified: CL increased with increasing height, volume of the central compartment (Vc) increased with increasing body surface area, and CL, Vc, and volume of the peripheral compartment were systematically different between phase 1 noninfected subjects and phase 3 infected patients. Visual predictive checks demonstrated minimal bias, supporting the robustness of the final models. These models were useful for generating individual PK exposures for pharmacokinetic-pharmacodynamic (PK-PD) analyses for efficacy and Monte Carlo simulations to evaluate PK-PD target attainment.

Uptake and virological outcomes of single- versus multi-tablet antiretroviral regimens among treatment-naïve youth in the HIV Research Network.

OBJECTIVES: Several single-tablet regimens (STRs) are now available and are recommended for first-line antiretroviral therapy (ART); however, STR use for youth with HIV (YHIV) has not been systematically studied. We examined the characteristics associated with initiation of STRs versus multi-tablet regimens (MTRs) and the virological outcomes for youth with nonperinatally acquired HIV (nPHIV). METHODS: A retrospective cohort study of nPHIV youth aged 13-24 years initiating ART between 2006 and 2014 at 18 US HIV clinical sites in the HIV Research Network was performed. The outcomes measured were initiation of STRs versus MTRs, virological suppression (VS) at 12 months, and time to VS. Demographic and clinical factors associated with initiation of STR versus MTR ART and VS (< 400 HIV-1 RNA copies/mL) at 12 months after initiation were assessed using multivariable logistic regression. Cox proportional hazards regression was used to assess VS within the first year. RESULTS: Of 987 youth, 67% initiated STRs. Of the 589 who had viral load data at 1 year, 84% of those on STRs versus 67% of those on MTRs achieved VS (P < 0.01). VS was associated with STR use [adjusted odds ratio (AOR) 1.61; 95% confidence interval (CI) 1.01-2.58], white (AOR 2.41; 95% CI 1.13-5.13) or Hispanic (AOR 2.38; 95% CI 1.32-4.27) race/ethnicity, and baseline CD4 count 351-500 cells/µL (AOR 1.94; 95% CI 1.18-3.19) and > 500 cells/µL (AOR 1.76; 95% CI 1.0-3.10). STR use was not associated with a shorter time to VS compared with MTR use [hazard ratio (HR) 1.07; 95% CI 0.90-1.28]. CONCLUSIONS: Use of STR was associated with a greater likelihood of sustained VS 12 months after ART initiation in YHIV.