ABSTRACT
BACKGROUND: Most studies focus on potential drug interactions, without considering the effect of these on the response to antiretroviral (ARV) therapy. We assess the effect of potential drug-drug interactions (pDDIs) that could have lowered the ARV concentration (pDDI-lowerARV) on HIV viral load. METHODS: Retrospective observational cohort study was conducted on all HIV-infected outpatients attending the Pharmacy Service of a regional reference hospital in Murcia (south-eastern Spain). The complete treatment was subsequently screened for pDDIs using the database 'InteraccionesHIV.com'. The study focused on interactions involving at least one ARV drug and, especially, any pDDI-lowerARV. RESULTS: Two hundred and twenty-nine patients were included in the study. A total of 168 pDDIs were identified, of which 62 (36.9%) had the potential to lower ARV concentrations. In 77% of cases, the drug involved in the reduction of plasma concentrations was a protease inhibitor (PI), and in the rest of the drug interactions the ARV drug affected was a non-nucleoside reverse-transcriptase inhibitor. Baseline viral suppression was noted in 57.1% of patients with pDDI-lowerARV compared with 61.5% of patients without pDDI-lowerARV (p=0.605), and in 85.7% versus 79.7%, respectively, after a 24-week follow-up period (p=0.516). CONCLUSIONS: This study shows that prevalence of pDDI-lowerARV was high; however, no association was found between the presence of these interactions and virological failure. These results confirm the need for further studies to understand the consequences of interactions in real-life clinical practice, since most pharmacokinetic studies tend to evaluate the ability of interaction between two drugs under controlled conditions.
