Rapid estimation of volume of distribution after a short intravenous infusion and its application to dosing adjustments.

A simple and a rapid method to estimate the apparent volume of distribution of drug after single or during multiple short-term intravenous infusion is proposed. This is based on the back extrapolation to the midpoint of infusion. An equation simpler than one previously reported in the literature is also derived to calculate the maintenance dose for multiple short-term intravenous infusion. In addition, an equation to estimate the "priming dose" for infusion during multiple infusion regimen is also derived. The derivations of the equations are based on a linear one-compartment open model for drug disposition in patients. The prposed method is thought to be adequate for the purpose of rapid individualization of dosage regimens. The simplicity of the method, in particular, the solution by the graphic method for estimation of the apparent volume of distribution, might be specially useful for clinicians not well versed in mathematics in applying clinical pharmacokinetics to drug therapy.