Determination of mean input time, mean residence time, and steady-state volume of distribution with multiple drug inputs.

A general treatment for determination of mean residence time (MRT) and steady-state volume of distribution (Vss) after multiple drug inputs via any mode of administration is presented. For multiple inputs, either simultaneous or consecutive, the mean input time (MIT) can be readily calculated using the general equations presented here. Sample calculations for MIT, MRT, and Vss following different combinations of multiple drug inputs are presented. Errors inherent in noncompartmental area determinations are discussed.