AN ALGORITHM FOR ESTIMATING THE TERMINAL HALF-LIFE IN PHARMACOKINETICSTUDIES

An algorithm is developed for automating the process of identifying th e terminal phase in plasma concentration-time curves for non-compartme ntal estimation of the terminal elimination rate and half-life. The ma nual process of plotting each curve, selecting the observations in the terminal phase, performing the regressions and plotting the fitted re gression lines can be very time-consuming in cases where many curves a re to be processed. The algorithm makes use of single-row regression d iagnostics to determine the first observed time point in the terminal phase. An example is used to illustrate the calculations, and a simula tion study was conducted to evaluate the performance of the algorithm. The algorithm has been implemented in a computer program.