WEIGHTED SERUM POOLS IN COMPARISON TO THE TRAPEZOIDAL RULE FOR ESTIMATING AUCS FOR ETHINYL ESTRADIOL - THE RELATIONSHIP OF THE VARIANCE OF THE DETERMINATION TO THE INTERINDIVIDUAL VARIANCE

The concept of a weighted pool for estimating the area under the curve (AUC) is presented and set in relationship to the trapezoidal rule. A n example from a pharmacokinetic study on ethinyl estradiol is used to demonstrate the use of variance component analysis for relating the i ntraindividual variance of the AUC, trapezoidal rule and weighted pool to the variance of the determination process. Depending on the sampli ng times, the theoretical variance of the weighted pool is greater tha n the theoretical variance of the trapezoidal rule. In the example pre sented, it was shown that this difference is of no importance in relat ion to the interindividual variance of the AUC, which dominates the to tal variance. In the example study, routine quality control samples we re also determined in each assay, which allowed independent confirmati on of the discussed results on the intraindividual variance of the AUC s.