Overview of Factors Governing Interindividual Variations

Patients on drug therapy manifest different responses to the same regimen. A drug may have little or no therapeutic effects in some patients but elicit adverse effects at low 

Intersubject variation in drug response is thought to cost lives and dramatically increase health care costs [1,2]. While 

Biotechnology and Biopharmaceuticals, by Rodney J. Y. Ho and Milo Gibaldi ISBN 0-471-20690-3 Copyright 2003 by John Wiley Sons, Inc. 

While an individual s phenotype can directly assess a clinical measureable biologic function of interest (e.g., whether an individual is a fast or slow metabolizer of a certain drug), phenotyping is often expensive and not readily adapted for routine clinical practice. Analysis of genetic information—genotyping—might prove to be more efficient and better able to be adapted to the individualization of drug therapy. 

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