Pharmacokinetics of the taxanes.

The pharmacokinetics of the taxanes paclitaxel and docetaxel have been studied extensively in humans. Paclitaxel has distinctly nonlinear pharmacokinetics, with saturable distribution and elimination features. Docetaxel pharmacokinetics are well described by linear processes, although some investigators detected subtle nonlinear characteristics. Clinically, nonlinear pharmacokinetics produce a disproportional relationship between dose and drug exposure. This affects dose adjustments and calculation and use of dose intensity to compare chemotherapy regimens. Although the underlying mechanism of nonlinearity in paclitaxel disposition is not well understood, both metabolic and distributive processes may be involved.