Pharmacokinetics of green tea catechins in extract and sustained-release preparations.

Catechins are a major constituent of green tea. For green tea to have cancer therapeutic benefit, catechin concentrations in the range of 100 nM are required continuously until apoptosis (programmed cell death) is induced. To prolong elevated plasma and interstitial concentrations of catechins, a sustained-release formulation of green tea extract was tested and compared to a commercial green tea extract (Tegreen97®). Sustained-release formulations are usually developed in the pharmaceutical industry to slowly deliver the compound over a period of time and increase the dosing interval. Plasma and interstitial fluid (ISF) pharmacokinetics of catechins were determined following an oral dose in the rat. The sustained-release formulation profile included multiple smaller peaks of total catechins in both plasma and ISF. Interstitial fluid profiles of green tea extract indicate that higher catechins concentration and longer duration in tissue than in blood may make a sustained-release form unnecessary.