A new method for calculating the mean total body drug clearance is proposed for determining the mean dosing rate for patients. In this method, the mean clearance can be calculated from the individual clearance values by the harmonic mean method, or it can be determined by dividing the same absorbed dose by the arithmetic mean of the areas under the plasma level-time curve from time zero to infinity from all of the subjects or patients studied. In this method, the arithmetic mean method is assumed to have been used for calculation of literature mean plasma levels. Various methods for calculating mean clearances also are evaluated. These methods yield different mean clearance values from the same set of individual data, resulting in different dosage regimen recommendations.