Multiparameter extrapolation of biodistribution data between species

Values of an inaccessible biological parameter in man may be predicted from values measured in animals by correlating with a parameter accessible in both species, such as body weight, energy production, excretion rate, etc. Predicting toxic effects, from environmental chemicals, of therapeutic doses for drug administration and of radiation absorbed dose from medical and environmental radioactivity depends on the rationalization of relationships between concentration and time when scaling to humans from animal data. For example, the retention of " T c, injected intravenously as pertechnetate, reaches 10% in the mouse at about 1 d, but this level occurs in humans at about 7 d. Making a simultaneous transformation between two species for the concentration and time variables by using a method of least-squares fitting, we have derived a series of transformation factors for several species. When correlated with a biological parameter such as body weight, these factors can be used to yield predicted values that are in good agreement with measured values. This system may be used with any related variables, making it useful for predicting other types of biological data.