27 October 2026
A new study by the Royal Australasian College of Physician’s Internal Medicine Journal has found major Australian prescribing resources provide little guidance to doctors about when pharmacogenomic testing could help them prescribe medicines more safely and effectively.
Pharmacogenomics uses information about a patient’s genes to help select medicines and doses that are more likely to be safe and effective. This includes chemotherapy, HIV medication, blood thinners, and antidepressants.
Medication-related hospitalisations account for an estimated 250,000 admissions and $1.4 billion in costs in Australia each year, with around half considered potentially preventable.
Research suggests pharmacogenomic-guided prescribing could prevent up to 30% of these adverse drug responses.
However, Ruby Soueid, lead author of the study, says that pharmacogenomic-guided prescribing is not widely adopted in Australia.
“There are many barriers, including limited knowledge and uncertainty of clinical value from professionals, testing costs, and a lack of consistent national guidelines.”
The study examined 67 medicine-gene combinations with strong evidence that a person’s genetics may affect their drug response.
It found the Australian Medicines Handbook included advice about when to consider genetic testing for just 28% of these combinations, while Therapeutic Guidelines and TGA-approved product information each included advice for only 19%.
Soueid says that the findings reveal a critical gap between advances in personalised medicine and the information available to doctors when prescribing.
“Genetic differences can affect whether a medicine works for a patient, what dose they need, and in some cases whether a medicine could cause serious harm.
“But when doctors turn to the prescribing guides they use every day, the information about when genetic testing should be considered is often not there.
“Where guidance is available, doctors can encounter different recommendations depending on which resources they consult.”The study also found that where Australian prescribing resources did provide advice, their recommendations weren’t always consistent.
When both the Australian Medicines Handbook and Therapeutic Guidelines provided advice about how to treat patients with particular genetic differences, their recommendations agreed in only four of seven cases.
For example, in patients with specific enzyme deficiency (complete thiopurine S-methyltransferase deficiency), who are prescribed certain treatments for leukaemia or inflammatory bowel disease, the Australian Medicines handbook advises against use of a particular medicine. Meanwhile, Therapeutic Guidelines recommends lower doses or adjusting the dosing interval.
“Medicare now funds pharmacogenomic tests for several medicines, but in some cases the prescribing resources clinicians use have not caught up.
“For example, Medicare has funded dihydropyrimidine dehydrogenase (DPYD) testing before fluoropyrimidine chemotherapy since November 2025, yet neither Australian Medicines Handbook nor Therapeutic Guidelines told prescribers when DPYD testing should be used.
“Fluoropyrimidines are widely used chemotherapy medicines. Some people with variants affecting the DPYD gene have substantially increased risks of toxicity from these medicines.”
The study also found that Australian pharmacogenomic guidance was inconsistent from international standards.
“Greater harmonisation is needed to support clinical decision-making and wider use of pharmacogenomics.
“Australia now has national testing guidance from the Royal College of Pathologists of Australasia, and Medicare is funding a growing number of these tests.
“The next step is making sure the guidance appears in the resources doctors are using every day when making decisions.
“Consistent guidance will make sure every patient receives the same evidence-based advice regardless of which doctor they see.”