Table 3.

Stability of the derivatized clopidogrel active metabolite (CAM-D) was evaluated at a concentration 100 ng/mL for ≤ 1 week (wk) stability, 4 months (mo) stability, and 9 mo stability. Stability of clopidogrel was evaluated at concentrations of 38.3 ng/mL for ≤ 1 wk stability and 76.6 ng/mL for 4 and 9 mo stability. Stability of clopidogrel carboxylic acid were evaluated at concentrations of 500 ng/mL for ≤ 1 wk stability and 2,500 ng/mL for 4 and 9 mo stability. Short term stability was assessed for up to 1 wk at room temperature (RT), 4°C, −20°C, or −80°C in citrate or EDTA treated feline plasma and up to 9 months (mo) at −80°C in citrate treated feline plasma. Long term stability at −80°C was not determined (ND) for EDTA treated feline plasma. Data are presented as percent deviation from the nominal concentration.

		Deviation from nominal concentration (%)
		Citrate treated plasma			EDTA treated plasma
Storage	Time	CAM-D	Clopidogrel	Clopidogrel carboxylic acid	CAM-D	Clopidogrel	Clopidogrel carboxylic acid
		−10	10	4	−2	−4	−11
		−10	6	9	1	−2	3
RT	24 h	−5	7	14	5	−2	−2
RT	48 h	−17	7	20	−4	−5	−10
RT	72 h	−20	0	17	−3	−1	1
RT	1 wk	−20	2	25	−13	6	−1
4°C	6 h	3	6	8	−15	−7	−6
4°C	12 h	0	6	13	7	1	11
4°C	24 h	−2	7	11	7	−1	−1
4°C	48 h	6	6	17	1	1	−7
4°C	72 h	3	2	7	2	−3	−11
4°C	1 wk	7	6	19	−2	−10	−15
−20°C	6 h	−5	7	0	4	−6	−6
−20°C	12 h	−9	7	18	6	0	10
−20°C	24 h	−9	6	10	6	−2	−1
−20°C	48 h	−4	6	16	0	−2	−6
−20°C	72 h	−16	5	8	2	−5	−1
−20°C	1 wk	−13	7	11	3	−2	1
−80°C	6 h	6	10	5	1	−2	−7
−80°C	12 h	−1	8	22	2	−1	−4
−80°C	24 h	3	10	19	0	1	−3
−80°C	48 h	10	5	17	5	−3	−10
−80°C	72 h	−8	1	7	7	1	−1
−80°C	1 wk	1	2	15	−1	1	1
−80°C	4 mo	12	8	15	ND	ND	ND
−80°C	9 mo	−12	14	−11	ND	ND	ND