Alison Duncan1 and Dianne Carey2
- Pharmacy Department, The Alfred Hospital, Melbourne, VIC 3004
- The Kirby Institute, UNSW Sydney, NSW 2052
Last reviewed: November 2019
Drug-drug interactions between antiretroviral (ARV) drugs and co-prescribed medication are common and may lead to an increase or decrease in exposure to either drug. These alterations in exposure may result in unexpected change/s in therapeutic response/s or increase the risk of adverse effects/toxicity. Drug-drug interactions may be beneficial, managed by dose adjustment, or may produce toxicity and thus be contraindicated. When prescribing a new drug or switching drug/s in an ARV regimen, it is important to consider the potential for interactions that may affect the ARV drugs and those that may affect other medications.
To prevent or minimize potential drug interactions, regular review of all medications, including alternative therapies and over-the-counter preparations, is essential. An easy to use on-line resource for checking drug interaction potential is the University of Liverpool’s HIV drug interaction checker tool (www.hiv-interactions.org). There are also helpful interaction tables available in the US Department of Health and Human Services Guidelines see: www.aidsinfo.nih.gov/guidelines
However, sometimes it can be difficult to predict the magnitude and clinical significance of interactions when several drugs with competing metabolic pathways are co-prescribed. Referral to a specialist HIV pharmacist can assist to thoroughly review the medication list and minimize potential problems.
When co-prescription is unavoidable, monitor the patient carefully for loss of efficacy and/or toxicity of ARV drugs and other medications.