The present invention is directed to the production, breeding and use oftransgenic non-human animals such as mice in which specific genes or portionsof genes have been replaced by homologues from another animal to make thephysiology of the animals so modified more like that of the other animal withrespect to drug pharmacokinetics and metabolism. The invention also extends tothe use of the genetically modified non-human animals of the invention forpharmacological and/or toxicological studies.
