1 Departments of Pediatrics, Neurology and Pathology, College of Physicians & Surgeons, Columbia University, New York, NY 10032
We appreciate the comments of Weinberger et al and Spino et al. The equation utilized in our original report to calculate the apparent volume of distribution (V) was in error, as it was based on determinations for drugs that exhibit monoexponential elimination following a single intravenous dose. The correct formula for oral dosing at steady state with a drug obeying one-compartment model kinetics is: V = F.X0/AUC
. K, where F is the total fraction of dose reaching systemic circulation, X0, is the dose, AUC
is the area under the curve during a dosing interval; K is the elimination rate constant.1