(a)
(b)
(c)
(d)
Figure 1: Representative chromatograms of blank plasma (a), blank plasma with IS (b), blank plasma with mixed probe drugs (c), and plasma sample collected at 45 min after oral administration of mixed probe drugs to rats (d). 1 = caffeine, 2 = chlorzoxazone, 3 = tolbutamide, 4 = midazolam, 5 = internal standard (IS) diazepam.