In Vitro Systems for Studying Respiratory System Toxicology

Possible Extraction of Drugs from Lung Tissue During Broncho-alveolar Lavage Suggest Uncertainty in the Procedure's Utility for Quantitative Assessment of Airway Drug Exposure

“…Bronchoalveolar lavage (BAL) is a commonly implemented technique in preclinical and clinical research. 2 The BAL procedure can be applied to harvest cells and alveolar surfactant from the lungs and for sampling of the epithelial lining fluid (ELF) to estimate the local lung concentration of a drug dosed systemically or by inhalation. It however needs to be taken into consideration that possible variations in local concentrations in ELF is lost during a lavage procedure.…”

“…For harvesting of cells and alveolar surfactant the usual approach is to harvest as much material as possible by thoroughly and repeatedly washing the lung surface whereas for drug extraction from ELF, a delicate procedure is required to avoid epithelial damage that can result in drug extraction from surrounding tissue. 2 When determining drug concentration in ELF, it is of course necessary to account for the difference in volume between the sampled ELF and the exogenous lavage fluid in which the drug concentration is actually assayed. Urea has often been used to estimate the dilution of the sample since it's concentrations are identical everywhere in the body, including the plasma and in situ ELF.…”