Bimodal intersecting distributions

Fig. 2.24 Frequency plots of bimodal intersecting log-normal distributions in various mix ratios.

Figure 11.1. Demonstrates a unimodal and bimodal distribution of drug metabolism. The theoretical unimodal (single gaussian distribution) on the left is typical of a nonpolymorphic metabolism, and the bimodal distribution (mixture of two Gaussian distributions) on the right represents the results of phenotyping for a polymorphic substrate, debrisoquine. The intersection of the two bimodal distributions is the antimode, or the estimated cutoff point between the two phenotypes used to predict the PM phenotype. Adapted, in part, from Henthorn T. K., Benitez, J., Avram,M. J., Martinez,C., Llerena, A., Cobaleda, J., Krejcie,T., and Gibbons, R. D. Clin. Pharmacol. Ther. 45, 328-333,1989 and Kiipfer, A., and Presage, R. Ear. J. Clin. Pharmacol. 26 753-759,1984.

This ves a mixture with a size distribution that asymptotically approaches the 60% parent size distribution at latge sizes and asymptotically approaches the 40% parent size distribution at small sizes. The location of the S-shaped intermediate size distribution depends on the relative fractions of each of the parent size distributions used. A relative percentage plot of the mixture size distribution and of the two parent size distributions is shown in Figure 2.13(b). Here we see two intersecting size distributions that when mixed show a bimodal distribution. 

Fig. 2.23 Parent distributions for bimodal log-normal intersecting mixtures.

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