Penetration of Anti-Infective Agents into Pulmonary Epithelial Lining Fluid

University of Illinois at Chicago, USA.
Clinical Pharmacokinetics (Impact Factor: 5.05). 10/2011; 50(10):637-64. DOI: 10.2165/11594090-000000000-00000
Source: PubMed


The exposure-response relationship of anti-infective agents at the site of infection is currently being re-examined. Epithelial lining fluid (ELF) has been suggested as the site (compartment) of antimicrobial activity against lung infections caused by extracellular pathogens. There have been an extensive number of studies conducted during the past 20 years to determine drug penetration into ELF and to compare plasma and ELF concentrations of anti-infective agents. The majority of these studies estimated ELF drug concentrations by the method of urea dilution and involved either healthy adult subjects or patients undergoing diagnostic bronchoscopy. Antibacterial agents such as macrolides, ketolides, newer fluoroquinolones and oxazolidinones have ELF to plasma concentration ratios of >1. In comparison, β-lactams, aminoglycosides and glycopeptides have ELF to plasma concentration ratios of ≤1. Potential explanations (e.g. drug transporters, overestimation of the ELF volume, lysis of cells) for why these differences in ELF penetration occur among antibacterial classes need further investigation. The relationship between ELF concentrations and clinical outcomes has been under-studied. In vitro pharmacodynamic models, using simulated ELF and plasma concentrations, have been used to examine the eradication rates of resistant and susceptible pathogens and to explain why selected anti-infective agents (e.g. those with ELF to plasma concentration ratios of >1) are less likely to be associated with clinical treatment failures. Population pharmacokinetic modelling and Monte Carlo simulations have recently been used and permit ELF and plasma concentrations to be evaluated with regard to achievement of target attainment rates. These mathematical modelling techniques have also allowed further examination of drug doses and differences in the time courses of ELF and plasma concentrations as potential explanations for clinical and microbiological effects seen in clinical trials. Further studies are warranted in patients with lower respiratory tract infections to confirm and explore the relationships between ELF concentrations, clinical and microbiological outcomes, and pharmacodynamic parameters.

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    • "Contemporary thought on the newer 'longer acting' injectable macrolides in veterinary medicine is that the most important index is AUC/MIC. However, intense debate remains whether this should be measured and reported for plasma (Toutain, 2009; Papich, 2014), at the site of infection (Amsden, 2001; Evans, 2005) or both (Rodvold et al., 2011). Although not statistically significant, the marginally significant association between plasma PKPD indices and treatment outcome (P = 0.10) would seem to substantiate the claims of using plasma drug concentrations. "
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    Journal of Veterinary Pharmacology and Therapeutics 10/2015; DOI:10.1111/jvp.12267 · 1.19 Impact Factor
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    • "a widely used technique for collecting the ELF to determine sufficient drug concentrations achieved at the infected site. This technique has been commonly applied to antibacterial agents (Rodvold et al., 2011a) and is also recently applicable to other anti-infective agents, such as antifungal, antitubercular, antiparasitic, and antiviral agents (Rodvold et al., 2011b). In the case of LO as well, it is likely that the ELF is a relevant site to determine drug concentrations from the standpoint of pharmacokinetic/pharmacodynamic relationship, considering viral surface location of the neuraminidase enzyme. "
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