Cloxacillin concentrations in serum, subcutaneous fat, and muscle in patients with chronic critical limb ischemia

Simultaneous determination of oxacillin and cloxacillin in plasma and CSF using turbulent flow liquid chromatography coupled to high-resolution mass spectrometry: Application in therapeutic drug monitoring

Cloxacillin and oxacillin are group M penicillins. The therapeutic monitoring of plasma concentrations of these antibiotics and those of their hydroxymethylated metabolites is of great clinical interest, especially in the choice of an adequate dosage allowing an effective treatment while limiting the occurrence of undesirable effects and the development of bacterial resistance. In this context, we conducted this work aiming at developing and validating a method allowing the determination of cloxacillin and oxacillin as well as the identification of their active metabolites in different biological matrices (CSF and plasma) using turbulent flow liquid chromatography coupled to high-resolution mass spectrometry. To do this, we carried out several optimisation tests. Subsequently, we validated our method according to the latest bioanalytical validation recommendations of the European Medicines Agency. The validation results showed that our method is specific and sensitive. We obtained good linearity in the range 0.5 to 100 µg/mL with correlation coefficients above 0.995. The lower limit of quantification was 0.5 µg/mL for each analyte. The method was found to be accurate with repeatability and reproducibility coefficients of variation below 15 %. Our method is also accurate with bias values below 15 %. Recovery values ranged from 87 % to 95 %. Finally, we were able to apply our method to the therapeutic monitoring of the analysed molecules and to identify their active metabolites. Our results suggest that LC-MS shows superiority in the therapeutic monitoring of these antibiotics due to the superiority of specificity shown by this method. This assay method can be routinely used for the daily plasma assays of patients treated with these antibiotics in the context of therapeutic monitoring.

Pharmacokinetics and Target Attainment of ß-lactam Antibiotics in Older People: A Systematic Review of Current Literature

BACKGROUND AND OBJECTIVE

(Patho)physiological changes in older people may influence the pharmacokinetics (PK), and consequently the target attainment, of ß-lactam antibiotics using standard dosing regimens. This systematic review compiles the current knowledge on the PK and target attainment of ß-lactam antibiotics in older people, with the aim to identify priorities for dose optimization in this patient population.

METHODS

A systematic literature search of the PubMed and EMBASE databases was conducted. Relevant articles published prior to 1 December 2021 were identified as eligible when they included data on the PK of ß-lactam antibiotics in adults ≥ 65 years of age. Extracted information included reported PK parameters (volume of distribution, clearance [CL], elimination rate constant, intercompartmental CL, elimination half-life, area under the concentration-time curve, maximum and trough concentration), covariates on PK parameters, target attainment rate, and dosing recommendations.

RESULTS

Ninety-one relevant articles were included in this review. Four main ß-lactam subclasses were represented: 59.3% on cephalosporins + cephamycins, 25.3% on penicillins, 15.4% on carbapenems, and 3.3% on monobactams; 65.9% of articles involved intravenous administration, 16.5% mixed administration routes, 12.1% oral administration, and 5.5% intramuscular administration. The majority of studies had a small sample size, often did not include detailed information on the study population and methods, and were fairly old. CL was, on average, decreased, while elimination half-life was prolonged in aged subjects compared with young subjects. Volume of distribution was generally similar between age groups. Most studies identified renal function as the most important contributor to altered drug CL. In only 30.8% of the articles, target attainment was studied, and in 35.7% of these articles, target attainment was found to be suboptimal. Dosing recommendations were incorporated in 87.9% of articles.

CONCLUSION

Studies frequently fail to provide an evidence-based dosing recommendation for this diverse patient population. Model-based PK studies that address both physiological and disease-related changes are urgently needed. This review identified gaps of knowledge to set priorities for further research.

Diagnosis and management of skin and soft-tissue infections (SSTI). A literature review and consensus statement: an update

Skin and soft-tissue infections (SSTIs) are among the most common bacterial infections, posing considerable diagnostic and therapeutic challenges. Fourteen members of the Italian Society of Infectious Diseases, after a careful review of the most recent literature using Medline database and their own clinical experience, updated a previous paper published in 2011 by preparing a draught manuscript of the statements. The manuscript was successively reviewed by all members and ultimately re-formulated the present manuscript during a full day consensus meeting. The microbiological and clinical aspects together with diagnostic features were considered for necrotizing and not necrotizing SSTIs in the light of the most recent guidelines and evidences published in the last five years. The antimicrobial therapy was considered as well - both empirical and targeted to methicillin-resistant Staphylococcus aureus and/or other pathogens, also taking into account the epidemiological and bacterial resistance data and the availability of new antibacterial agents.