TY - JOUR T1 - Systemic bioavailability of inhaled steroids: the importance of appropriate and comparable methodology JF - European Respiratory Journal JO - Eur Respir J SP - 157 LP - 158 DO - 10.1183/09031936.01.17101570 VL - 17 IS - 1 AU - H. Derendorf AU - P.T. Daley-Yates AU - L.N. Pierre AU - J. Efthimiou Y1 - 2001/01/01 UR - http://erj.ersjournals.com/content/17/1/157.abstract N2 - To the Editors: Recently, the systemic bioavailability of mometasone furoate (MF) via the TwisthalerTM (Schering Corp., Kenilworth, NJ, USA) has been reported to be <1% in healthy subjects 1. This unusual result, however, was based on a study with sparse data, a low dose (i.e. 400 µg) and a relatively insensitive assay (lower limit of detection of 50 pg·mL−1). Plasma concentrations were said to be undetectable in 10 of the 24 subjects in whom this assay was used.The absolute systemic bioavailability for an inhaled drug is calculated by comparing the area under the plasma concentration-time curve for inhaled dosing, with that obtained following intravenous dosing. To obtain a reliable estimate, the administered doses need to be large enough to produce measurable plasma concentrations. Therefore, an estimate of the true systemic bioavailability of MF cannot reliably be made based on incomplete data and an insensitive assay, and certainly not compared with … ER -