Genomics in general practice

Pharmacogenomics: Summary

Last revised: 30 Nov 2018

Practice point

While there are international guidelines about potential uses of pharmacogenomic testing, there is limited evidence from randomised controlled trials of the clinical utility and cost effectiveness of using pharmacogenomics to tailor prescribing, especially in primary care.1,2
 

The term ‘pharmacogenomics’ describes how common gene variants influence drug metabolism and response.

There are common variants in cytochrome P450 enzymes (CYPs) and drug receptors that influence the rate of metabolism of many commonly prescribed drugs. Individuals are typically classified as ‘poor’, ‘intermediate’, ‘extensive’ or ‘ultrarapid’ metabolisers depending on their CYP variants. Poor and ultrarapid metabolisers may require different dosages, or be more susceptible to adverse drug effects.3

Table 1 provides examples of drugs that may be affected by common gene variants.

Table 1. Examples of drugs affected by common gene variants

Table 1

Examples of drugs affected by common gene variants1

Pharmacogenomic testing may be considered for patients with:

  • significant side effects from drugs for where pharmacogenomic variation in response is known (refer to Table 1)
  • poor therapeutic response to specific medications
  • potential suitability for using doses outside the usual range.

Pharmacogenomic testing is not subsidised under the Medicare Benefits Schedule (MBS), but can be ordered by general practitioners through a number of commercial providers.

Refer to ‘Pharmacogenomics: More information’ for a detailed discussion of this topic.

Centre for Genetics Education, Fact sheet 21: Pharmacogenetics/pharmacogenomics
National Library of Medicine, What is pharmacogenetics?

 

  1. Clinical Pharmacogenetics Implementation Consortium. CPIC guidelines. Stanford, CA: CPIC, 2014. Available at
  2. https://cpicpgx.org [Accessed 8 January 2018].
  3. Relling MV, Evans WE. Pharmacogenomics in the clinic. Nature 2015;526(7573):343.
  4. Abbasi J. Getting pharmacogenomics into the clinic. JAMA 2016;316(15):1533–35.
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