Telavancin was discovered by modifying the chemical structure of vancomycin and belongs to the group of lipoglycopeptides. It employs its antimicrobial potential through two distinct mechanisms of action: inhibition of bacterial cell wall synthesis and induction of bacterial membrane depolarization and permeabilization. In this article we review the clinically relevant pharmacokinetic and pharmacodynamic data of telavancin. For comparison, the pharmacokinetic and pharmacodynamic data of the other glycopeptides are presented. Although, in contrast to the newer lipoglycopeptides, telavancin demonstrates a relatively short half-life and rapid total clearance, its apparent volume of distribution (Vd) is almost identical to that of dalbavancin. The accumulation of telavancin after repeated dosing is only marginal, whereas the pharmacokinetic values of the other glycopeptides show much greater differences after administration of multiple doses. Despite its high plasma–protein binding of 90% and relatively low Vd of approximately 11 L, telavancin shows near complete equilibration of the free fraction in plasma with soft tissue. The ratio of the area under the plasma concentration–time curve from time zero to 24 h (AUC24) of unbound plasma concentrations to the minimal inhibitory concentration (MIC) required to inhibit growth of 90% of organisms (MIC90) of Staphylococcus aureus and S. epidermidis of telavancin are sufficiently high to achieve pharmacokinetic/pharmacodynamic targets indicative for optimal bacterial killing. Considering both the AUC24/MIC ratios of telavancin and the near complete equilibration of the free fraction in plasma with soft tissue, telavancin is an appropriate antimicrobial agent to treat soft tissue infections caused by Gram-positive pathogens. Although the penetration of telavancin into epithelial lining fluid (ELF) requires further investigations, the AUC24/MIC ratio for S. aureus indicates that bactericidal activity in the ELF could be expected.
Objectives: Continuous infusion (CON) of fosfomycin has been proposed as potentially advantageous in certain clinical scenarios. However, no clinical data on the pharmacokinetics (PK) of fosfomycin after CON are available to date. This study aimed at investigating the PK of fosfomycin after CON and compare it with intermittent infusion (INT) of fosfomycin. Methods: A randomized two-way crossover study including 8 healthy male volunteers was performed. Each subject received fosfomycin as INT of 8g over 30 minutes every 8 hours and, separated by a wash-out period, as CON of 1g/hour preceded by a loading dose of 8g over 30 minutes. PK sampling was performed for 18 and 24 hours in the CON and INT group, respectively. Results: Fosfomycin was generally well tolerated. However, 2 out of 8 subjects (25%) developed thrombophlebitis at the infusion site following CON, which was prevented in the following subjects with simultaneous co-infusion of Ringer's lactate. Steady-state Cmax and AUCSS, 0-24 of fosfomycin after INT were 551.5 ± 67.8 mg/L and 3678.5 ± 601.9 h*mg/L, respectively. CON led to an average steady-state concentration of 183.8 ± 35.9 mg/L, resulting in a calculated AUCSS, 0-24 of 4411.2 ± 862.4 h*mg/L, which was 1.2-fold higher compared with INT. CON resulted in 100% T>MIC for MICs ≤ 128 mg/L, whereas %T>MIC for INT was only 44% for a MIC of 128 mg/L. Conclusions: CON of fosfomycin led to improved PK and PK/PD determinants in plasma of healthy volunteers. The clinical relevance of these findings remains to be investigated in patients.
About one-sixth of the world's population is affected by a neglected tropical disease as defined by the World Health Organization and Center for Disease Control. Parasitic diseases comprise most of the neglected tropical disease list and they are causing enormous amounts of disability, morbidity, mortality, and healthcare costs worldwide. The burden of disease of the top five parasitic diseases has been estimated to amount to a total 23 million disability-adjusted life-years. Despite the massive health and economic impact, most drugs currently used for the treatment of parasitic diseases have been developed decades ago and insufficient novel drugs are being developed. The current review provides a compilation of the systemic and target-site pharmacokinetics of established antiparasitic drugs. Knowledge of the pharmacokinetic profile of drugs allows for the examination and possibly optimization of existing dosing schemes. Many symptoms of parasitic diseases are caused by parasites residing in different host tissues. Penetration of the antiparasitic drug into these tissues, the target site of infection, is a prerequisite for a successful treatment of the disease. Therefore, for the examination and improvement of established dosing regimens, not only the plasma but also the tissue pharmacokinetics of the drug have to be considered. For the current paper, almost 7000 scientific articles were identified and screened from which 429 were reviewed in detail and 100 were included in this paper. Systemic pharmacokinetics are available for most antiparasitic drugs but in many cases, not for all the relevant patient populations and only for single-or multiple-dose administration. Systemic pharmacokinetic data in patients with organ impairment and target-site pharmacokinetic data for relevant tissues and body fluids are mostly lacking. To improve the treatment of patients with parasitic diseases, research in these areas is urgently needed.
Background Preclinical data suggested anti-inflammatory properties of tedizolid. Objectives To investigate the influence of tedizolid on the cytokine response to the human endotoxin challenge and the effect of endotoxaemia on the pharmacokinetics and protein binding of tedizolid. Methods In this cross-over trial, 14 male healthy volunteers underwent two treatment periods: (A) 200 mg of tedizolid phosphate once daily for 6 days (3 days orally and 3 days intravenously), followed by an intravenous bolus of 2 ng/kg body weight of LPS on the last treatment day; and (B) intravenous bolus of LPS (2 ng/kg body weight) without concomitant tedizolid treatment. Participants underwent first period A or B, separated by at least 6 weeks. Plasma was sampled to assess cytokines and the pharmacokinetics of tedizolid. Results Following the endotoxin challenge, the peak plasma concentration (median [IQR]; 280 [155–502] versus 287 [132–541] pg/mL; P = 0.875) and AUC0–24 (979 [676–1319] versus 1000 [647–1632] pg·h/mL; P = 0.638) of interleukin-6 remained unchanged with and without concomitant tedizolid treatment. The peak concentration and AUC0–24 of TNF-α remained also unchanged with and without tedizolid (47 [31–61] versus 54 [27–69] pg/mL; P = 0.73 and 197 [163–268] versus 234 [146–280] pg·h/mL; P = 0.875, respectively). The total maximum concentration (mean ± SD; 2.94 ± 0.69 versus 2.96 ± 0.62 mg/L), total AUC0–24 (22.3 ± 3.8 versus 21.1 ± 3.6 mg·h/L) and protein binding (21.4% ± 1.7% versus 21.6% ± 1.9%) of tedizolid were similar with and without the endotoxin challenge. Conclusions Tedizolid did not attenuate the LPS-induced cytokine response in healthy volunteers. Furthermore, endotoxaemia did not influence the plasma pharmacokinetics of tedizolid.
Background and Objective Exhaustive pharmacokinetic (PK) studies in paediatric patients are unavailable for most antibiotics and feasibility of PK studies is limited by challenges, such as low blood volume and venipuncture-related pain. Microdialysis (MD) represents a promising method to overcome these obstacles. The aim of this proof-of-concept study was to develop and validate modified MD catheters that can be used to obtain concentration-time profiles of antibiotics in paediatric patients. Methods Following extensive in vitro MD experiments, a prospective open-labelled study in ten healthy adult volunteers (HVs) was conducted. Subjects received a single intravenous dose of 1000 mg vancomycin, then plasma and intravascular microdialysate were sampled over 24 h. In vivo MD probe calibration was conducted using the retrodialysis technique. Plasma protein binding was measured using ultrafiltration. Confirmation of the measurements was performed using a Bland-Altman plot, relevant PK parameters were calculated, and a pharmacometric model was established. Results No safety issues were encountered. The concentration-time curves of microdialysate and plasma measurements showed good alignment. The Bland-Altman plot yielded a mean bias of 0.19 mg/L and 95% limits of agreement of − 9.34 to 9.71 mg/L. A two-compartment model best described plasma PK, model-based estimates for recovery of the MD probes being in high agreement with the observed values. Quantified estimates of fraction unbound were comparable between plasma and microdialysate (p = 0.56). Conclusions An innovative MD catheter that can be inserted into small intravenous lines was successfully developed and applied in HV. This proof-of-concept study is encouraging and opens the way to further experiments leading towards future use of MD in paediatric patients.
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