Drug development, radiolabelled drugs and PET

Positron emission tomography (PET) provides noninvasive in vivo quantitativ e pharmacokinetic and pharmacodynamic information on novel and established drugs. Because only very low amounts of the (potential) drug have to be adm inistered, far below toxicity levels, human studies can be carried out even before the drug is entered in phase I studies. Such studies can provide co st-effective predictive toxicology data and information on the metabolism a nd mode of action of drugs. PET is also very useful in the study of the met abolic consequences of gene expression or gene defects, In the last decade, several models using genetically engineered small animals have been develo ped. The study of these animals with high-resolution small animal PET camer as provides new opportunities in drug development. Especially valuable is t he contribution of PET in bridging the gap between molecular biology, basic pathology and the design of a new generation of drugs.