A High Throughput HPLC-MS/MS Method for Antihypertensive Drugs Determination in Plasma and Its Application on Pharmacokinetic Interaction Study with Shuxuetong Injection in Rats

Table 5

Stability of the analytes in rat plasma (n = 3).

Compounds	Spiked; Concentration (ng/mL)	room temperature for 4 h		three freeze-thaw cycles		auto-sampler for 12 h		-70°C for 14 days
		Measured; (ng/mL)	RSD; (%)	Measured; (ng/mL)	RSD; (%)	Measured; (ng/mL)	RSD; (%)	Measured; (ng/mL)	RSD; (%)
metoprolol tartrate	20	20.95 ± 0.73	3.5	20.05 ± 1.71	8.5	21.42 ± 0.17	0.8	22.12 ± 1.33	6.0
	400	437.09 ± 4.45	1.0	412.18 ± 8.83	2.1	408.30 ± 5.14	1.3	448.14 ± 4.22	0.9
	4000	3939.11 ± 62.55	1.6	3941.70 ± 205.62	5.2	3732.32 ± 25.44	0.7	3590.13 ± 57.20	1.6
hydrochlorothiazide	25	25.88 ± 0.34	1.3	26.69 ± 1.29	4.8	25.45 ± 0.29	1.1	26.74 ± 3.13	11.7
	500	560.13 ± 0.70	0.1	517.28 ± 11.62	2.3	468.47 ± 1.66	0.4	531.65 ± 21.94	4.1
	5000	4719.25 ± 205.46	4.4	4739.30 ± 167.66	3.5	4700.72 ± 23.23	0.5	4745.30 ± 36.49	0.8
	5	5.46 ± 0.34	6.3	5.14 ± 0.06	1.2	4.87 ± 0.10	2.0	4.61 ± 0.09	2.0
nifedipine	100	100.30 ± 0.78	0.8	99.39 ± 1.34	1.4	97.56 ± 1.09	1.1	97.93 ± 1.18	1.2
	1000	873.99 ± 21.28	2.4	928.74 ± 16.08	1.7	927.25 ± 3.49	0.4	860.37 ± 22.96	2.7
	50	54.29 ± 0.94	1.7	49.32 ± 2.03	4.1	48.57 ± 1.40	2.9	52.12 ± 3.14	6.0
valsartan	1000	937.54 ± 19.41	2.1	901.96 ± 6.34	0.7	990.30 ± 7.76	0.8	1066.59 ± 68.31	6.4
	10000	9192.99 ± 167.34	1.8	9957.94 ± 963.19	9.7	8701.16 ± 60.77	0.7	8719.00 ± 100.69	1.2