Authors: Zhu M.¹; Chen Y.¹; Li R. C.²

Source: Xenobiotica, Volume 31, Number 1, 1 January 2001 , pp. 51-60(10)

Publisher: Informa Healthcare

Abstract:

1. The pharmacokinetics and dose proportionality of three tea catechins were assessed. 2. Male Sprague-Dawley rats (210-230 g) received intravenous (i.v.) doses (50, 100, 200 and 300 mg kg^-1) of a decaffeinated tea fraction containing (-)-epicatechin (EC: 5%), (-)-epigallocatechin gallate (EGCG: 50%) and (-)-epicatechin gallate (ECG: 13%). 3. Catechins in plasma, urine and faeces were quantitated by HPLC. 4. A two-compartment model was utilized to describe the bi-exponential disposition exhibited by the three catechins. 5. Over this dose range, the central distribution volume (V_c) for these catechins increased significantly (p<0.05) from 0.17-0.34 to 0.42-0.66l kg^-1. 6. A concentration-dependent increase in the plasma free fraction of catechins that mirrored the increases in V_c was observed. 7. The estimates of steady-state volume of distribution (V_ss) were between 0.68 and 2.08l kg^-1 at the lowest dose, and tended to increase with dose. 8. Appreciable amount of catechins partitioned into red blood cells (range 9-43%) and was apparently independent of concentration. 9. The mean elimination half-life (t_1/2,) for EC, EGCG and ECG across doses were 43, 124, and 222 min respectively, and were invariant with dose. 10. Parallel to V_c, a 2-3-fold dose-dependent increase (p<0.05) in systemic clearance (CL) was observed for the three catechins. 11. Urinary recovery was highest (21-31%) for EC, while those for EGCG and ECG was only ~3-5%. 12. Faecal recoveries of the catechins were between 0.5 and 5%. 13. In conclusion, the pharmacokinetics of the catechins appeared to be non-linear; dose-dependent changes in xenobiotic distribution might contribute to this observation.

Language: English

Document Type: Research article

Affiliations: 1: Department of Pharmacy, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong 2: Department of Pharmacy, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong and Pharmacokinetics/Pharmacofynamics, Bioanalytical & Drug Disposition, Wyeth-Ayerst Research, Pearl River, 10965 NY, USA

Publication date: 2001-01-01

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