Quantitation of Diclofenac, Tolbutamide, and Warfarin as Typical CYP2C9 Substrates in Rat Plasma by UPLC-MS/MS and Its Application to Evaluate Linderane-Mediated Herb-Drug Interactions

Table 5

Stability of diclofenac, tolbutamide, and warfarin in rat plasma.

Compounds	Added concentration (μg/mL)	Postpreparative stability		Short-term stability		Freeze-thaw stability		Long-term stability
		Found concentration (μg/mL)	RSD (%)	Found concentration (μg/mL)	RSD (%)	Found concentration (μg/mL)	RSD (%)	Found concentration (μg/mL)	RSD (%)
Diclofenac	0.060	0.06 ± 0.00	3.7	0.06 ± 0.00	3.8	0.06 ± 0.00	6.6	0.06 ± 0.00	6.1
	3.8	3.63 ± 0.06	1.6	3.66 ± 0.08	2.1	3.88 ± 0.13	3.5	3.92 ± 0.11	2.9
Tolbutamide	0.600	0.58 ± 0.02	3.3	0.58 ± 0.03	4.8	0.56 ± 0.02	2.8	0.57 ± 0.01	2.2
	75.0	74.62 ± 0.84	1.1	75.78 ± 0.84	1.1	75.82 ± 1.51	2.0	75.15 ± 4.69	6.2
Warfarin	0.15	0.16 ± 0.01	4.0	0.16 ± 0.01	3.8	0.15 ± 0.00	2.8	0.16 ± 0.01	7.4
	15	13.90 ± 0.29	2.1	14.20 ± 0.14	1.0	14.68 ± 0.08	0.5	14.00 ± 0.37	2.6