Development of analytical technology in pharmacogenetic research

Methods used to determine phenotype and genotype for pharmacogenetic polymorphisms are discussed. Phenotyping is mainly applicable to polymorphisms affecting drug disposition rather than drug response and can involve either direct measurement of enzyme activity or administration of a probe drug followed by measurement of drug and/or metabolite levels. Genotyping is now more widely used than phenotyping and can be used to determine genotype for polymorphisms affecting either drug disposition (for example those in the cytochromes P450 or N-acetyltransferases) or drug response (for example those in drug receptors). Most genotyping for known polymorphisms involves use of the polymerase chain reaction and the wide variety of methods based on this technique that are now used for routine genotyping are discussed in detail. In addition, a range of methods that can be used to detect novel polymorphisms, thereby further increasing understanding of interindividual variability in drug disposition and response, is described.