Abstract
SAFit-1 and SAFit-2 are selective FKBP51 (FK506-binding protein 51) ligands. In
this paper, we present the development and validation data of an
LC-MS/MS method for the simultaneous quantitation of SAFit-1 and SAFit-2
in mice plasma as per FDA regulatory guideline. SAFit-1 and SAFit-2 along with
internal standard were extracted from mice plasma using liquid-liquid extraction
method. Chromatographic resolution of SAFit-1, SAFit-2 and the internal standard
(warfarin) was achieved on an X-Terra phenyl column using 0.2% formic
acid:acetonitrile (20:80, v/v) as an eluent, which was delivered at a
flow-rate of 0.9 mL/min. The MS/MS ion transitions monitored
were m/z 748.4→420.4, 803.7→384.3 and 309.2
→163.2 for SAFit-1, SAFit-2 and the internal standard, respectively. The
linearity range was 2.45–2446 ng/mL for both SAFit-1 and
SAFit-2. The intra- and inter-day accuracy and intra- and inter-day precision
were in the range of 0.90–1.07 and 2.38–10.8%,
respectively for SAFit-1; 0.97–1.15 and 0.23–12.5%,
respectively for SAFit-2. Both SAFit-1 and SAFit-2 were found to be stable in
stability studies (up to three freeze-thaw cycles and for long-term at
−80°C for 30 days) and processed (bench-top for 3 h and in
in-injector for 16 h) samples. The application of the validated method was shown
in a pharmacokinetic study in mice.
Key words
antidepressant drugs - drug research - pharmacokinetics