A technique for calculating the mean time for equilibration of drug distribution using minimal structural assumptions.

Disposition decomposition analysis is used as a framework to derive a parameter for the description of drug distribution kinetics. This parameter, denoted td, is a measure of the mean time for equilibration of distribution in the absence of metabolic drug elimination. The derivation requires only the assumption that distribution is linear, and is generally valid as long as any nonlinearity is due to central nonlinear elimination. The mean time for equilibration of distribution, td, is evaluated in terms of the moments of the distribution function, h(t), derived by disposition decomposition analysis. Estimates of td for several drugs are presented.