Bioassay evaluation assuming multiple unknown parameters applying optimal design

Bioassays can be used to estimate the intake in accidental and routinely situations. To evaluate the effective dose, apart from the intake, we need to know other parameters such as Activity Median Aerodynamic Diameter (AMAD) or the fraction absorption (f1) in the blood from the GI tract. In an accident situation these parameters are often unknown. The bioassay measurement values can be used to estimate by fitting the parameters unknown. We have applied non linear regression for solving this kind of problem. Furthermore, a method to find the best moments where the bioassay measurements should be taken is described. This method is applied to optimal designs. The goodness of the design will depend on the number of samples and the measurement accuracy. It requires obtaining the analytical solution of the biokinetic model as a function of the parameters to be fitted. Different cases are studied using the computer program BIOKMOD (developed by one of the authors. A web version of Biokmod is available at http://www3.enusa.es/webMathematica/Public/biokmod.html