Introduction & module overview

Pharmacogenetics/pharmacogenomics can explain how the genetic make-up of individual patients may influence the effectiveness and safety of commonly used medicines. Examples are the variability in therapeutic effects of codeine and in the occurrence of severe adverse effects of, say,  carbamazepine and allopurinol. 

The age, weight, height and sex of a person may influence the choice and dose of medicines. We already accept that checking liver or renal function using blood tests is important in determining which drugs, and what doses, are safe to use in some patients, and in subsequent monitoring and dose titration. These features are known as pharmacodynamic and pharmacokinetic factors. 

Knowledge about how the genetic make-up of individual patients might affect their response to drugs (through their expression of pharmacodynamic or pharmacokinetic factors) is less well advanced. 

Genetic differences in the response to drugs are described as pharmacogenetic and pharmacogenomic factors. Although describing subtly different things, these two terms are often used interchangeably. This CPD module will mainly refer to pharmacogenomics (PGx). 

Many pharmacists may not have been taught about PGx in their initial training, so this module introduces the subject to enable informed responses to questions from patients.