Pharmacokinetics of moxifloxacin and high-dose levofloxacin in severe lower respiratory tract infections

Tigecycline in the Treatment of Ventilator-Associated Pneumonia Due to Stenotrophomonas maltophilia: A Multicenter Retrospective Cohort Study

Introduction

Tigecycline is a potential alternative to trimethoprim–sulfamethoxazole in treating Stenotrophomonas maltophilia infections due to its potent in vitro antimicrobial activity. Clinical evidence regarding the use of tigecycline in the treatment of S. maltophilia infections is scarce. In this study, we assessed the efficacy of tigecycline treating ventilator-associated pneumonia (VAP) due to S. maltophilia in comparison with fluoroquinolones.

Methods

This is a multicenter retrospective cohort study of patients admitted between January 2017 and December 2020 with the diagnosis of VAP caused by S. maltophilia receiving either tigecycline or fluoroquinolones as the definitive therapy ≥ 48 h. Clinical outcomes including 28-day mortality, clinical cure and microbiological cure were analyzed.

Results

Of 82 patients with S. maltophilia VAP included, 46 received tigecycline, and 36 received fluoroquinolones; 70.7% of patients had polymicrobial pneumonia, and the appropriate empiric therapy was applied to only 14.6% of patients. The overall 28-day mortality was 39%. Compared with patients receiving fluoroquinolones, tigecycline therapy resulted in worse clinical cure (32.6% vs. 63.9%, p = 0.009) and microbiological cure (28.6% vs. 59.1%, p = 0.045), while there was no statistical difference between 28-day mortality (47.8% vs. 27.8%, p = 0.105) in the two groups. Similar results were also shown in the inverse probability of treatment weighted univariable regression model and multivariable regression model.

Conclusions

The standard dose of tigecycline therapy was associated with a lower clinical and microbiological cure rate but not associated with an increased 28-day mortality in patients with S. maltophilia VAP compared with fluoroquinolones. Considering the unfavorable clinical outcomes, we therefore recommend against using the standard dose of tigecycline in treating S. maltophilia VAP unless new clinical evidence emerges.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-021-00516-5.

Moxifloxacin in Chronic Obstructive Pulmonary Disease: Pharmacokinetics and Penetration into Bronchial Secretions in Ward and Intensive Care Unit Patients

This study aimed to evaluate the pharmacokinetic profile of moxifloxacin (MXF) in serum and sputum/bronchial secretions of 22 patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) hospitalized in the ward and intensive care unit (ICU). The data showed that ICU patients had lower concentrations in secretions (P = 0.01). However, no other statistically significant differences were observed in pharmacokinetic parameters and penetration in secretions between ward and ICU patients. MXF showed a favorable pharmacokinetic profile, and the pharmacodynamic targets for common pathogens for AECOPD were achieved.

Population Pharmacokinetic Model and Limited Sampling Strategies for Personalized Dosing of Levofloxacin in Tuberculosis Patients

Levofloxacin is an antituberculosis drug with substantial interindividual pharmacokinetic variability; therapeutic drug monitoring (TDM) could therefore be helpful to improve treatment results. TDM would be more feasible with limited sampling strategies (LSSs), a method to estimate the area under the concentration curve for the 24-h dosing interval (AUC0-24) by using a limited number of samples. This study aimed to develop a population pharmacokinetic (popPK) model of levofloxacin in tuberculosis patients, along with LSSs using a Bayesian and multiple linear regression approach. The popPK model and Bayesian LSS were developed using data from 30 patients and externally validated with 20 patients. The LSS based on multiple linear regression was internally validated using jackknife analysis. Only clinically suitable LSSs (maximum time span, 8 h; minimum interval, 1 h; 1 to 3 samples) were tested. Performance criteria were root-mean-square error (RMSE) of <15%, mean prediction error (MPE) of <5%, and r2 value of >0.95. A one-compartment model with lag time best described the data while only slightly underestimating the AUC0-24 (mean, -7.9%; standard error [SE], 1.7%). The Bayesian LSS using 0- and 5-h postdose samples (RMSE, 8.8%; MPE, 0.42%; r2 = 0.957) adequately estimated the AUC0-24, with a mean underestimation of -4.4% (SE, 2.7%). The multiple linear regression LSS using 0- and 4-h postdose samples (RMSE, 7.0%; MPE, 5.5%; r2 = 0.977) was internally validated, with a mean underestimation of -0.46% (SE, 2.0%). In this study, we successfully developed a popPK model and two LSSs that could be implemented in clinical practice to assist TDM of levofloxacin. (This study has been registered at ClinicalTrials.gov under identifier NCT01918397.).

High-performance liquid chromatography with time-programmed fluorescence detection for the quantification of Levofloxacin in human plasma and cerebrospinal fluid in adults with tuberculous meningitis

An accurate and reliable high-performance liquid chromatography with time-programmed fluorescence detection was developed and validated to measure levofloxacin in human plasma and cerebrospinal fluid (CSF). After solid phase extraction process using Evolute^® ABN 96 fixed well plate; levofloxacin and internal standard-enoxacin were separated using a mobile phase consisting of phosphate buffer 10mM with 0.025% triethylamine pH 3.0 - acetonitrile (88:12, v/v) on a Purosphere RP-8e column (5μm, 125×4.0mm) at a flow rate of 1.2mL/min at 35°C. The excitation/emission wavelengths were set to 269/400nm and 294/500nm, for enoxacin and levofloxacin, respectively. The method was linear over the concentration range of 0.02 to 20.0μg/mL with a limit of detection of 0.01μg/mL. The relative standard deviation of intra-assay and inter-assay precision for levofloxacin at four quality controls concentrations (0.02, 0.06, 3.0 and 15.0μg/mL) were less than 7% and the accuracies ranged from 96.75% to 101.9% in plasma, and from 93.00% to 98.67% in CSF. The validated method was successfully applied to quantify levofloxacin in a considerable quantity of plasma (826) and CSF (477) samples collected from 232 tuberculous meningitis patients, and the preliminary intensive pharmacokinetics analysis from 14 tuberculous meningitis patients in Vietnam is described in this paper.

Pharmacokinetic/pharmacodynamic considerations for the optimization of antimicrobial delivery in the critically ill

PURPOSE OF REVIEW

Antimicrobials are very commonly used drugs in the intensive care setting. Extensive research has been conducted in recent years to describe their pharmacokinetics/pharmacodynamics in order to maximize the pharmacological benefit and patient outcome. Translating these new findings into clinical practice is encouraged.

RECENT FINDINGS

This article will discuss mechanistic data on factors causing changes in antimicrobial pharmacokinetics in critically ill patients, such as the phenomena of augmented renal clearance as well as the effects of hypoalbuminemia, renal replacement therapy, and extracorporeal membrane oxygenation. Failure to achieve clinical cure has been correlated with pharmacokinetics/pharmacodynamics target nonattainment, and a recent meta-analysis suggests an association between dosing strategies aimed at optimizing antimicrobial pharmacokinetics/pharmacodynamics with improvement in clinical cure and survival. Novel dosing strategies including therapeutic drug monitoring are also now being tested to address challenges in the optimization of antimicrobial pharmacokinetics/pharmacodynamics.

SUMMARY

Optimization of antimicrobial dosing in accordance with pharmacokinetics/pharmacodynamics targets can improve survival and clinical cure. Dosing regimens for critically ill patients should aim for pharmacokinetics/pharmacodynamics target attainment by utilizing altered dosing strategies including adaptive feedback using therapeutic drug monitoring.

In vitro activity of levofloxacin against lower respiratory tract pathogens

Background:

Considerable morbidity and mortality are associated with lower respiratory tract infections (LRTIs) that put a considerable strain on the health budget. Selection of appropriate antibiotics as empirical therapy maximizes positive patient outcomes, and that depends on regular surveillance of infective agents and their antibiograms, which vary according to the geographical areas.

Aim:

The aim was to study the drug susceptibility pattern of the isolated pathogens of the respiratory tract infections.

Settings and Design:

Retrospective study for a period of 1-year 3 months from January 2013 to March 2014 at a Tertiary Care Hospital.

Materials and Methods:

Eleven hundred and eighty-four sputum samples from both outdoor and indoor patients with symptoms of LRTI were processed, and antibiotic sensitivity test was done to commonly used antibiotics. Descriptive statistics was used to analyze the data.

Results:

Among 502 quality sputum samples, 312 (62.15%) samples showed growth of pathogenic bacteria. The most common pathogens were Klebsiella spp. (38.14%), Moraxella spp. (16.02%), Streptococcus pneumoniae (14.10%), Pseudomonas spp. (9.93%), S. aureus (9.29%). It was found that the overall susceptibility pattern was <50% for amoxicillin, amoxicillin-clavulanic acid, cefuroxime, cotrimoxazole and erythromycin whereas for cefotaxime, cefixime, and cefoperazone-sulbactum it was 60.08%, 51.59%, 69.04%, respectively. The susceptibility to ciprofloxacin, ofloxacin, and levofloxacin were 66.67%, 70.19% and 83.33%, respectively.

Conclusion:

Klebsiella spp. was the most common LRTI pathogen. There was limited activity of amoxicillin, amoxicillin-clavulanic acid, cefuroxime, cotrimoxazole and erythromycin for the treatment of LRTI whereas levofloxacin, (being an oral drug with good compliance) had good activity against respiratory pathogens and could be used for empiric treatment in LRTI.

Moxifloxacin pharmacokinetic profile and efficacy evaluation in empiric treatment of community-acquired pneumonia

When antimicrobials are used empirically, pathogen MICs equal to clinical breakpoints or epidemiological cutoff values must be considered. This is to ensure that the most resistant pathogen subpopulation is appropriately targeted to prevent emergence of resistance. Accordingly, we determined the pharmacokinetic (PK) profile of moxifloxacin at 400 mg/day in 18 patients treated empirically for community-acquired pneumonia. We developed a population pharmacokinetic model to assess the potential efficacy of moxifloxacin and to simulate the maximal MICs for which recommended pharmacokinetic-pharmacodynamic (PK-PD) estimates are obtained. Moxifloxacin plasma concentrations were determined the day after therapy initiation using ultra-high-performance liquid chromatography. Peak drug concentrations (Cmax) and area under the free drug concentration-time curve from 0 to 24 h (fAUC0-24) values predicted for each patient were evaluated against epidemiological cutoff MIC values for Streptococcus pneumoniae, Haemophilus influenzae, and Legionella pneumophila. PK-PD targets adopted were a Cmax/MIC of ≥12.2 for all pathogens, an fAUC0-24/MIC of >34 for S. pneumoniae, and an fAUC0-24/MIC of >75 for H. influenzae and L. pneumophila. Individual predicted estimates for Cmax/MIC and fAUC0-24/MIC as well as simulated maximal MICs resulting in target attainment for oral and intravenous administration of the drug were suitable for S. pneumoniae and H. influenzae but not for L. pneumophila. These results indicate that caution must be taken when moxifloxacin is used as monotherapy to treat community-acquired pneumonia caused by L. pneumophila. In conclusion, this report reveals key information relevant to the empirical treatment of community-acquired pneumonia while highlighting the robust and flexible nature of this population pharmacokinetic model to predict therapeutic success. (Clinical Trials Registration no. NCT01983839.).