Spatial expression and functionality of drug transporters in the intact lung: objectives for further research

This commentary provides a background appraising evidence in the intact lung on the spatial expression of drug transporters and, where available, evidence in the intact lung of the impact, or otherwise, that such transporters can have upon pulmonary drug absorption and disposition. Ultimately drug discovery and development scientists will wish to identify in a 'pulmonary' context the effect of disease upon transporter function, the potential for drug transporters to contribute to drug-drug interactions and to inter-individual variation in drug handling and response. The rate and extent of lung epithelial permeation of drugs involve an interplay between the dose and the deposition site of drug within the lung and physiological variables operational at the epithelial-luminal interface. Amongst the latter variables is the potential impact of active transporter processes which may well display regio-selective characteristics along the epithelial tract. In pulmonary tissues the spatial pattern of drug transporter expression is generally poorly defined and the functional significance of transporters within the intact lung is explored in only a limited manner. Active transporters in the lung epithelium may affect airway residence times of drug, modulate access of drug to intracellular targets and to submucosal lung tissue, and potentially influence airway to systemic drug absorption profiles. Transporters in the lung tissue may also have the capacity to mediate uptake of drug from the systemic circulation resulting in drug accumulation in the lung. Transporters have physiological roles and new drug candidates while not necessarily serving as transport substrates may modulate transporter activity and hence physiology. The commentary highlights a series of recommendations for further work in pulmonary drug transporter research.

Pediatric Antibiotic Stewardship: Optimization of Vancomycin Therapy Based on Individual Pharmacokinetics

BACKGROUND

Vancomycin has been a first-line treatment for Gram-positive infections for decades. However, strategies for therapeutic drug monitoring (TDM) and dose-optimization in pediatrics remain controversial. In this study, we analyzed the impact of specific antibiotic stewardship interventions on efficacy and safety of vancomycin therapy.

METHODS

From September 2014 to May 2017, we conducted a prospective study to compare a control and a TDM intervention group in our tertiary care center. As part of an antibiotic stewardship program, we implemented internal guidelines on correct vancomycin dosing, TDM timing, as well as targeted trough level range and installed a pharmacokinetic (PK) consultation service to adapt vancomycin dosing to individually calculated PK parameters. As primary clinical outcomes, the percentage of patients with sustained therapeutic vancomycin trough levels and treatment days with therapeutic vancomycin trough levels, that is, 10-15 mg/L were analyzed. Secondary outcomes included nephrotoxicity, readmission rate and mortality. Median daily dose required to achieve therapeutic trough levels was examined.

RESULTS

Clinical outcomes for 90 control patients were compared with outcomes for 19 patients guided by a PK consultation service. Percentage of patients with sustained therapeutic vancomycin trough levels increased from 17.8% to 94.7% (P < 0.001) and percentage of treatment days with therapeutic vancomycin trough levels increased from 18.4% (117/637) to 665% (155/233, P < 0.001). Readmission rate decreased from 24.4% to 5.3% (P = 0.07). No differences in nephrotoxicity or mortality rate were observed between groups. A median daily dose of 72 mg/kg/d was required to achieve therapeutic trough levels.

CONCLUSIONS

Our data demonstrate that implementation of internal guidelines and a PK consultation service was associated with a profound improvement of vancomycin therapy and, therefore, patient safety.