Sample collection, analytical methods, and pharmacokinetic
analysis
Blood samples were collected for PK analysis of carotegrast methyl,
carotegrast, and other metabolites including M-I, M-II, and carotegrast
glucuronide (carotegrast-gluc) at 0, 0.5, 1, 2, 4, 6, 8, 10, 12, 15, and
24 h post-dose on days 1 and 7. A blood sample was collected on day 14
when subjects visited for follow-up observation. Plasma concentrations
of carotegrast methyl, carotegrast, M-I, M-II, and carotegrast-gluc were
measured by validated methods using liquid chromatography-tandem mass
spectrometry at Toray Research Center, Inc. (Tokyo, Japan). The linear
analytical ranges of carotegrast methyl and its metabolites including
carotegrast, M-I, and M-II were 0.5 − 500 ng mL-1, and
that of carotegrast-gluc was 2.0 − 200 ng mL-1. Plasma
concentrations of rifampicin were not measured in this study.
The primary PK parameters analyzed for carotegrast methyl and its
metabolites included area under the time concentration curve (AUC) from
time of dosing to time of last measurable concentration
(AUC0-t), AUC from time of dosing to infinity
(AUC0‐inf), maximum drug concentration
(Cmax), time to Cmax(Tmax), t1/2, and mean residence time
from time of dosing to time of last measurable concentration
(MRT0-t).