Potential drug–drug interactions due to concomitant medicine use among people living with HIV on antiretroviral therapy in Australia
de Oliveira Costa J., Lau S., Medland N., Gibbons S., Schaffer AL., Pearson SA.
Aims: We quantified concomitant medicine use and occurrence of potential drug–drug interactions in people living with HIV in Australia who are treated with antiretroviral therapy (ART). Methods: In this cohort study using dispensing claims of a 10% random sample of Australians, we identified 2230 people dispensed ART between January 2018 and December 2019 (mean age 49.0 years, standard deviation 12.0 years, 88% male). We examined concomitant medicine use by identifying nontopical medicines dispensed within 90-days of any antiretroviral medicine dispensing during a 12-month follow-up period. For every antiretroviral and nonantiretroviral pair, we identified and classified possible drug–drug interactions using the University of Liverpool HIV drug interactions database. Results: A total of 1728 (78%) people were dispensed at least 1 and 633 (28%) 5 or more unique medicines in addition to ART in a 12-month period; systemic anti-infectives and medicines acting on the nervous system were the most common (68% and 56%, respectively). Among comedicated people, 1637 (95%) had at least 1 medicine combination classified as weak interactions, 558 (32%) interactions requiring close monitoring/dose adjustment and 94 (5%) that should not be coadministered. Contraindication or interactions requiring close monitoring/dose adjustment were more common among people receiving protease inhibitors (50–73% across different antiretrovirals), non-nucleoside reverse transcriptase inhibitors (35–64%), people using single-tablet combinations containing elvitegravir (30–46%) and those using tenofovir disoproxil (26–30%). Conclusion: Concomitant medicine use is widespread among people living with HIV in Australia. Despite a relatively low prevalence of contraindicated medicines, almost a third received medicines that require close monitoring or dose adjustment.