Table 1. Pharmacokinetic parametersa of capecitabine and its metabolites in plasma, malignant tissue, and healthy connective tissue.

Compartment	Parameter	Capecitabine	DFCR	DFUR	FU
Plasma	cmax (μg ml−1)	2.34	6.53	3.65	0.25
		(0.64–15.4)	(1.79–8.7)	(1.67–7.22)	(0.09–0.80)
	tmax (h)	1.75	1.75	2.0	2.5
		(1.0–3.0)	(1.0–3.0)	(1.0–3.0)	(1.0–3.5)
	T1/2 (h)	0.50	0.86	0.80	N.A.
		(0.21–0.92)	(0.6–2.33)	(0.44–2.44)
	AUC0−5 h (μg ml−1 h)	2.36	11.3	6.42	0.29
		(1.13–17.3)	(4.74–16.5)	(4.26–10.0)	(0.13–1.86)
Tumour	cmax (μg ml−1)	2.66	4.22	2.13	0.26
		(0.91–15.7)	(1.54–4.29)	(0.85–4.29)	(0–0.74)
	tmax (h)	2.5	2.5	2.5	3.0
		(1.5–3.5)	(1.5–3.5)	(1.5–4.0)	(1.0–4.5)
	t1/2 (h)	0.50	0.87	1.08	N.A.
		(0.27–1.24)	(0.43–1.59)	(0.48–2.17)
	AUC0−5 h (μg ml 1 h)	3.52	7.89	3.35	0.25
		(0.92–33.3)	(2.15–25.2)	(1.43–13.4)	(0–2.28)
s.c. Tissue	cmax (μg ml−1)	2.70	4.37	1.51	0.33
		(0.58–28.2)	(1.11–10.1)	(0.70–5.87)	(0.08–1.40)
	tmax (h)	2.25	2.5	2.75	2.0
		(1.0–3.5)	(1.5–3.5)	(1.5–3.5)	(0.5–3.5)
	t1/2 (h)	0.59	0.76	0.82	N.A.
		(0.17–1.5)	(0.57–3.57)	(0.64–2.80)
	AUC0−5 h (μg ml−1 h)	3.16	8.40	2.75	0.36
		(0.78–43.5)	(2.31–22.1)	(1.51–11.6)	(0.13–2.21)

Patients received 1250 mg capecitabine m⁻² orally with tap water before collecting plasma samples and interstitial tissue fluid up to 5 h after administration.

^aValues are reported as median and range in parentheses (n=10). DFCR=5′-deoxy-5-fluorocytidine; DFUR=5′-deoxy-5-fluorouridine; FU=5-fluorouracil; cmax=maximum concentration; tmax=time to maximum concentration; t_1/2=elimination half-life; AUC_0−5 h=area under the concentration-time curve from 0 to 5 h; NA=not applicable.