Development of a high-performance liquid chromatographic electrospray massspectrometric assay for the specific and sensitive quantification of the novel immunosuppressive macrolide 40-O-(2-hydroxyethyl)rapamycin

It was our objective to develop a rapid, sensitive and specific assay to qu antify the immunosuppressive macrolide 40-O-(2-hydroxyethyl)rapamycin (SDZ- RAD) in blood of transplant patients. SDZ-RAD was extracted from blood by s olid-liquid extraction. SDZ-RAD and its internal standard 28,40-diacetyl ra pamycin were quantified using HPLC-electrospray MS. The assay was linear fr om 0.1 to 100 mu g/l (r(2)=0.99). The mean recovery was 83% for SDZ-RAD and 80.5% for the internal standard. The mean day-to-day precision was 8.0%. E xtracted samples were stable at 20 degrees C for at least 48 h and SDZ-RAD blood samples at -80 degrees C for at least six months. (C) 1998 Elsevier S cience B.V. All rights reserved.