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Drug interaction resources: mind the gaps

2020; NPS MedicineWise; Volume: 43; Issue: 1 Linguagem: Inglês

10.18773/austprescr.2020.005

1839-3942

Louise Grannell,

Health Sciences Research and Education

Drug interactions can lead to significant toxicity or loss of clinical effect.The risks increase with the number of drugs the patient takes.General and specialised drug interaction resources are available.Access to up-to-date electronic resources is encouraged.There are gaps in the information on interactions for new drugs, those with complicated metabolism and drugs with limited use.It may be necessary to use multiple resources to find the information.When assessing information about interactions, clinicians should evaluate the relevance for each patient.In high-risk situations, expert advice can be valuable.Clinicians should report new or unusual drug interactions to the Therapeutic Goods Administration.a shared action, such as QT prolongation, 4 increasing serotonin, or lowering of the seizure threshold.Patient factors, such as organ dysfunction, age, concurrent medical conditions, electrolyte disturbances and genetic factors, may influence the risk or severity of the interaction.Toxicity from drug-drug interactions can occur not only when starting or changing doses, but also when ceasing treatment, for example the strong induction effect of carbamazepine on cytochrome enzymes takes at least two weeks to reverse.Some drugs take a long time to be completely cleared such as amiodarone. 5Patients should be monitored accordingly. 6 Drug interaction resourcesGeneral and specialised resources are available to help assess the clinical impact of drug interactions.These include dedicated drug-drug interaction resources for antiretroviral drugs, hepatitis C therapies, antifungals, anticancer drugs and complementary medicines (Table 1).A subscription may be needed.The Australian Medicines Handbook (AMH) provides practical information on drug interactions considered likely to be clinically important.When appropriate it gives specific information on drug metabolism, but does not include primary references.MIMS and the Australian Drug Information (AusDI) interaction checkers, Stockley's Drug Interactions and Lexicomp assign their own 'severity/risk rating' or 'importance' for interactions.They give the probable mechanism of interaction, advise on actions to be taken and include clinical evidence and supporting, or in some cases disputing, references.