Subcutaneously administered antibiotics.

The subcutaneous route is a widely used route of administration in routine clinical practice, particularly in elderly patients, when the intravenous route cannot be used. This review of the literature highlights the lack of randomized studies and the lack of pharmacokinetic data on the use of this route of administration. Three antibiotics administered subcutaneously can be used for severe infections, with acceptable pharmacokinetic and pharmacodynamic data, when the intravenous administration is not possible: ceftriaxone, ertapenem, and teicoplanin.

Model-Informed Drug Development, Pharmacokinetic/Pharmacodynamic Cutoff Value Determination, and Antibacterial Efficacy of Benapenem against Enterobacteriaceae.

Benapenem is a novel carbapenem. The objective of this study was to determine the pharmacokinetic (PK)/pharmacodynamic (PD) cutoff values and evaluate the optimal administration regimens of benapenem for the treatment of bacterial infections via PK/PD modeling and simulation. Ertapenem was used as a control. Infected mice received an intravenous (i.v.) injection of benapenem or ertapenem of 14.6, 58.4, or 233.6 mg/kg of body weight, and the PK/PD profiles were evaluated. The MICs were determined by using a 2-fold agar dilution method. Mathematical models were developed to characterize the pharmacokinetic profile of benapenem in humans and mice. Monte Carlo simulations were employed to determine the cutoff values and the appropriate benapenem dosing regimens for the treatment of infections caused by clinical isolates of Enterobacteriaceae Two 2-compartment models were developed to describe the PK profiles of benapenem in humans and mice. A two-site binding model was applied to fit the protein binding in mouse plasma. Through correlation analysis, the percentage of the time that the free drug concentration remains above the MIC (%fT>MIC) was determined to be the indicator of efficacy. Results from the simulation showed that the probability of target attainment (PTA) against the tested isolates was over 90% with the dosing regimens studied. The PK/PD cutoff value of benapenem was 1 mg/liter at a %fT>MIC of 60% when given at a dose of 1,000 mg/day by i.v. drip for 0.5 h. The established model provides a better understanding of the pharmacological properties of benapenem for the treatment of Enterobacteriaceae infections. The proposed PK/PD cutoff value suggests that benapenem is a promising antibacterial against the Enterobacteriaceae The cutoff value of 1 mg/liter may be a useful guide for the clinical use of benapenem and for surveillance for benapenem resistance.

Is the subcutaneous route an alternative for administering ertapenem to older patients? PHACINERTA study.

BACKGROUND: Antibiotic administration by subcutaneous (SC) injection is common practice in French geriatric wards as an alternative to the intravenous (IV) route, but few pharmacokinetic/pharmacodynamic data are available. Ertapenem is useful for the treatment of infections with ESBL-producing enterobacteria. OBJECTIVES: To report and compare ertapenem pharmacokinetic data between IV and SC routes in older persons. METHODS: Patients >65 years of age receiving ertapenem (1 g once daily) for at least 48 h (IV or SC, steady-state) were prospectively enrolled. Total ertapenem concentrations [residual (C0), IV peak (C0.5) and SC peak (C2.5)] were determined by UV HPLC. Individual-predicted AUC0-24 values were calculated and population pharmacokinetic analyses were performed. Using the final model, a Monte Carlo simulation involving 10 000 patients evaluated the influence of SC or IV administration on the PTA. Tolerance to ertapenem and recovery were also monitored. ClinicalTrials.gov identifier: NCT02505386. RESULTS: Ten (mean ± SD age=87±7 years) and 16 (age=88±5 years) patients were included in the IV and SC groups, respectively. The mean C0 and C2.5 values were not significantly different between the IV and SC groups (C0=12±5.9 versus 12±7.4 mg/L, P=0.97; C2.5=97±42 versus 67±41 mg/L, P=0.99). The mean C0.5 was higher in the IV group compared with the SC group (C0.5=184±90 versus 51±66 mg/L, P=0.001). The mean individual AUCs (1126.92±334.99 mg·h/L for IV versus 1005.3±266.0 mg·h/L for SC, P=0.38) and PTAs were not significantly different between groups. No severe antibiotic-related adverse effects were noted. CONCLUSIONS: SC administration of ertapenem is an alternative to IV administration in older patients.

Pharmacokinetics of Ertapenem in Sheep (Ovis aries) with Experimentally Induced Urinary Tract Infection.

Sheep are commonly used as animal models for human biomedical research, but descriptions of their use for studying the pharmacokinetics of carbapenem antimicrobials, such as ertapenem, are unavailable. Ertapenem is a critical antimicrobial for human infections, and the description of the pharmacokinetics of this drug is of value for research using ovine as models for human diseases, such as urinary tract infections (UTI). There are currently no ovine models for comparative biomedical research of UTI. The objective of this study was to report the pharmacokinetics of ertapenem in sheep after single and multiple dosing. In addition, we explored the effects of an immunomodulatory drug (Zelnate) on the pharmacokinetics of ertapenem in sheep. Eight healthy ewes (weight, 64.4 ± 7.7 kg) were used in an ovine bacterial cystitis model of human cystitis with Pseudomonas aeruginosa. After disease confirmation, each ewe received 1 g of ertapenem intravenously once every 24 h for 5 administrations. Blood was collected intensively (14 samples) during 24 h after the first and last administration. After multiple-dose administration, the volume of distribution was 84.5 mL/kg, clearance was 116.3 mL/h/kg, T1/2(λz) was 1.1 h, and the extraction ratio was 0.02. No significant differences in pharmacokinetic parameters or time points were found between groups treated with the immunostimulant and controls or after the 1st or 5th administration of ertapenem. No accumulation was noted from previous administration. Our ovine pharmacokinetic findings can be used to evaluate therapeutic strategies for ertapenem use (varying drug dosing schedules and combinations with other antimicrobials or immune modulators) in the context of UTI.

Poly (bromocresol green) flakes-decorated pencil graphite electrode for selective electrochemical sensing applications and pharmacokinetic studies.

A square wave voltammetric method for selective determination of meropenem (MRP) and ertapenem (ERP) was developed using pencil graphite electrode modified with poly (bromocresol green) (PGE/PBCG). The modified electrode film was characterized by scanning electron microscopy and electro-chemical impedance spectroscopy. Under the optimized conditions, the prepared electrode has good linearity over concentration range 1.0-60.0 and 0.3.0-75.0 µM for MRP and ERP, respectively. The developed method was validated according to ICH guidelines. In addition, the diffusion co-efficients of MRP and ERP were estimated to be 1.24 × 10-6 and 9.09 × 10-6 cm2 s-1, respectively using chronoamperometric technique. The developed method was highly sensitive and selective for the determination of MRP or ERP in the presence of their corresponding open beta-lactam ring degradation products. Consequently, it was successfully utilized for in-vitro and in-vivo applications in spiked and real plasma samples of healthy rabbits for their pharmacokinetic studies. Furthermore, the method was applied for the assay of the available dosage forms of both drugs.

Pharmacokinetic-Pharmacodynamic Evaluation of Ertapenem for Patients with Hospital-Acquired or Ventilator-Associated Bacterial Pneumonia.

Ertapenem provides activity against many pathogens commonly associated with hospital-acquired and ventilator-associated bacterial pneumoniae (HABP and VABP, respectively), including methicillin-susceptible Staphylococcus aureus and numerous Gram-negative pathogens with one major gap in coverage, Pseudomonas aeruginosa Pharmacokinetic-pharmacodynamic (PK-PD) target attainment analyses were conducted to evaluate ertapenem against the most prevalent Enterobacteriaceae causing HABP/VABP. The objective of these analyses was to provide dose selection support for and demonstrate the appropriateness of ertapenem to empirically treat patients with HABP/VABP when administered with murepavadin, a novel targeted antimicrobial exhibiting a highly specific spectrum of activity against P. aeruginosa A previously developed population pharmacokinetic model, a total-drug epithelial lining fluid (ELF) to free-drug serum penetration ratio, contemporary in vitro surveillance data for ertapenem against Enterobacteriaceae, and percentage of the dosing interval for which drug concentrations exceed the MIC value (%T>MIC) targets associated with efficacy were used to conduct Monte Carlo simulations for five ertapenem regimens administered over short or prolonged durations of infusion. Overall total-drug ELF percent probabilities of PK-PD target attainment based on a %T>MIC target of 35% among simulated patients with HABP/VABP arising from Enterobacteriaceae based on pathogen prevalence data for nosocomial pneumonia ranged from 89.1 to 92.7% for all five ertapenem regimens evaluated. Total-drug ELF percent probabilities of PK-PD target attainment ranged from 99.8 to 100%, 97.9 to 100%, 10.6 to 74.1%, and 0 to 1.50% at MIC values of 0.06, 0.12, 1, and 4 µg/ml, respectively (MIC90 values for Escherichia coli, Serratia marcescens, Enterobacter species, and Klebsiella pneumoniae, respectively). Results of these analyses provide support for the evaluation of ertapenem in combination with murepavadin for the treatment of patients with HABP/VABP.

Modeling Ertapenem: the impact of body mass index on distribution of the antibiotic in the body.

Ertapenem is an antibiotic commonly used to treat a broad spectrum of infections and is part of a broader class of antibiotics called carbapenems. Unlike other carbapenems, ertapenem has a longer half-life and thus only has to be administered once a day. Previously, a physiologically-based pharmacokinetic (PBPK) model was developed to investigate the uptake, distribution, and elimination of ertapenem following a single one gram dose in normal height, normal weight males. Due to the absorption properties of ertapenem, the amount of fat in the body can influence how the drug binds, how quickly the drug passes through the body, and thus how effective the drug might be. Thus, we have revised the model so that it is applicable to males and females of differing body mass index (BMI). Simulations were performed to consider the distribution of the antibiotic in males and females with varying body mass indexes. These results could help to determine if there is a need for altered dosing regimens in the future.

Pharmacokinetics and investigation of optimal dose ertapenem in intermittent hemodialysis patients.

BACKGROUND: Previous pharmacokinetic studies demonstrated an increase in serum ertapenem concentrations with decreasing kidney function, including patients receiving renal replacement therapy. This study evaluated the pharmacokinetic parameters of ertapenem in patients receiving hemodialysis. METHODS: This prospective, single-center, open-label study examined the pharmacokinetics of a single intravenous (IV) dose of ertapenem 1 g in seven hospitalized noninfected patients undergoing hemodialysis. Blood samples were collected prior to ertapenem administration and at 0.5, 1, 2, 6, 12 and 48 hours (h) after administration. Ertapenem concentrations were determined by validated liquid chromatography mass spectrometry assay. RESULTS: Following an IV bolus of 1 g ertapenem, plasma concentrations declined relatively slowly with a mean ±standard deviation (SD) elimination half-life of 19.3 ±6.6 h. Plasma concentrations were similar in all subjects, with maximum mean plasma concentration observed of 343±48 µg/mL postdose. The mean ±SD values for systemic plasma clearance (CL) and volume of distribution at steady state (Vss) were 2±0.5 mL/min and 3295±1187 mL, respectively. The area under the curve for 0 h-∞ (AUCinf) was 7494 ±1424 h•µg/mL. No gender effect was observed and no serious adverse events were reported. CONCLUSIONS: Ertapenem half-life was prolonged in hemodialysis patients. Considering the nonrenal clearance and the expected 70% removal with high-efficacy hemodialysis, the dose of 1 g ertapenem, three times weekly, after hemodialysis may produce pharmacodynamically sufficient exposure for potential antimicrobial efficacy. Further studies are warranted to assess the clinical efficacy and safety of this dose with prolonged duration of therapy.

Ertapenem for osteoarticular infections in obese patients: a pharmacokinetic study of plasma and bone concentrations.

PURPOSE: Ertapenem is used off-label to treat osteoarticular infections but there are few pharmacokinetic (PK) data to guide optimal dosing strategies in patients who may be obese with multiple co-morbidities including diabetes and peripheral vascular disease. METHODS: Participants undergoing lower limb amputation or elective joint arthroplasty received a dose of intravenous ertapenem prior to surgery. Eight plasma samples were collected over 24 h, together with at least one bone sample per patient. Ertapenem concentrations in plasma and bone were measured using liquid-chromatography/mass-spectroscopy and analysed using non-linear mixed effects PK modelling. RESULTS: Plasma and bone concentrations were obtained from 10 participants. The final population PK model showed that a fat free body mass was the most appropriate body size adjustment. Ertapenem diffused rapidly into bone but concentrations throughout the 24 h dosing period were on average 40-fold higher in plasma, corresponding to a bone to plasma ratio of 0.025, and highly variable between individuals. Simulations demonstrated a high probability of target attainment (PTA) for free plasma concentrations when the minimum inhibitory concentrations (MIC) were ≤ 0.25 mg/L. By contrast, at MICs of 0.5 mg/L and ≥ 1 mg/L, the fractions of patients attaining this target was ~ 80% and 40%, respectively. In bone, the PTA was ≤ 45% when the MIC was ≥ 0.25 mg/L. CONCLUSION: Local bone and free plasma concentrations appear adequate for osteoarticular infections where Enterobacteriaceae are the main causative pathogens, but for Staphylococcus aureus and other bacteria, conventional dosing may lead to inadequate PTA.

Population Pharmacokinetic Analyses for Ertapenem in Subjects with a Wide Range of Body Sizes.

Despite a number of studies reporting that ertapenem pharmacokinetic parameters differ considerably in obese patients from those in healthy volunteers, functions describing the relationships between this agent's pharmacokinetics and indicators of body size have not been developed. The aim of this analysis was to develop an ertapenem population pharmacokinetic model using data from a previously described study in normal-weight, obese, and morbidly obese healthy volunteers. A single ertapenem 1-g dose administered intravenously was evaluated in 30 subjects within different body mass index (BMI) categories. The population pharmacokinetic model was developed using the first-order conditional estimation method with interaction (FOCE-I) algorithm within NONMEM. The ability of age, sex, renal function, and various body size measures (total body weight, height, body mass index, ideal body weight, fat-free mass, and body surface area [BSA]) to explain a portion of the interindividual variability on select pharmacokinetic parameters was explored using stepwise forward selection (α = 0.01) and backward elimination (α = 0.001). The data were best described using a linear three-compartment model with total body weight as a covariate on clearance (CL = 1.79 · [weight/95.90]0.278) and BSA as a covariate on central volume (Vc = 4.76 · [BSA/2.06]1.86). After accounting for fixed effects, the estimated interindividual variability was very low (<10% for all clearance and volume terms). Goodness-of-fit diagnostics indicated a precise and unbiased fit to the data. Using the developed population pharmacokinetic model and simulation, reliable estimates of ertapenem serum exposures, which can be utilized to evaluate various dosing regimens in subjects with a wide range of body sizes, are expected.

Pharmacokinetics of 2,000 Milligram Ertapenem in Tuberculosis Patients.

Ertapenem is a carbapenem antibiotic with activity against Mycobacterium tuberculosis Dose simulations in a hollow-fiber infection model showed that 2,000 mg once daily is an appropriate dose to be tested in clinical studies. Before using this dose in a phase II study, the aim of this prospective pharmacokinetic study was to confirm the pharmacokinetics of 2,000 mg once daily in tuberculosis (TB) patients. Twelve TB patients received a single intravenous dose of 2,000 mg ertapenem as a 30-min infusion. Blood samples were collected at 0, 0.5, 1, 2, 3, 4, 8, 12, and 24 h postadministration. Drug concentrations were measured using a validated liquid chromatography-tandem mass spectrometry assay. A large interindividual variation in the pharmacokinetics of ertapenem was observed. The median (interquartile range) area under the plasma concentration-time curve to infinity (AUC0-∞) was 2,032 (1,751 to 2,346) mg · h/liter, the intercompartmental clearance (CL12) was 1.941 (0.979 to 2.817) liters/h, and the volume of distribution in the central compartment (V1) was 1.514 (1.064 to 2.210) liters. A more than dose-proportional increase in AUC was observed compared to results reported for 1,000 mg ertapenem in multidrug-resistant TB patients. Based on a MIC of 1.0 mg/liter, 11 out of 12 patients would have reached the target value of unbound drug exceeding the MIC over 40% of the time (f40% T>MIC). In conclusion, this study shows that 2,000 mg ertapenem once daily in TB patients reached the expected f40% T>MIC for most of the patients, and exploration in a phase 2 study can be advocated.

Population pharmacokinetics and probability of target attainment of ertapenem administered by subcutaneous or intravenous route in patients with bone and joint infection.

Background: Ertapenem is a therapeutic option in patients with Gram-negative bone and joint infection (BJI). The subcutaneous (sc) route of administration is convenient in the outpatient setting and has shown favourable pharmacokinetics (PK), but available data on ertapenem are limited. Objectives: To perform population PK analysis and pharmacokinetic/pharmacodynamic (PK/PD) simulation of ertapenem administered by the intravenous (iv) or sc route to patients with BJI. Patients and methods: This was a retrospective analysis of PK data collected in patients with BJI who received iv or sc ertapenem. Measured ertapenem concentrations were analysed with a non-parametric population approach. Then, simulations were performed based on the final model to investigate the influence of ertapenem route of administration, dosage and renal function on the probability of achieving a pharmacodynamic (PD) target, defined as the percentage of time for which free plasma concentrations of ertapenem remained above the MIC (fT>MIC) of 40%. Results: Forty-six PK profiles (13 with iv and 33 with sc ertapenem) with a total of 133 concentrations from 31 subjects were available for the analysis. A two-compartment model with linear sc absorption and linear elimination best fitted the data. Creatinine clearance was found to significantly influence ertapenem plasma clearance. Simulations showed that twice daily dosing, sc administration and renal impairment were associated with an increase in fT>MIC and target attainment. Conclusions: Our results indicate that 1 g of ertapenem administered twice daily, by the iv or sc route, may optimize ertapenem exposure and achievement of PK/PD targets in patients with BJI.