ABSTRACT
Preclinical drug metabolism and pharmacokinetic studies should be initiated as soon as a drug candidate has demonstrated continued promise during second-level pharmacological testing and preliminary toxicity evaluation. Pharmacokinetics is an important tool in modern drug disposition research. Small changes in protein binding can have a considerable effect on drug distribution, since protein binding acts to keep the drug in the vascular compartment and, in this manner, causes less drug to be available for tissue distribution. A drug metabolism study begins with planning how and where to radiolabel the potential drug candidate and also with developing a nonisotopie blood level and/or urine assay for the parent molecule. Data obtained in the course of such studies are frequently treated, without consideration of the possible or probable effects of a disease state as though these findings would also apply to a patient. Comparatively little work has been directed toward the study of drug biotransformation in the newborn human infant.
