Background Studies demonstrate that human immunodeficiency virus (HIV) patients may be at greater risk of age-related comorbidities, polypharmacy and medicines-related problems, such as drug-drug interactions (DDIs).

Purpose To describe the characteristics of polypharmacy and DDIs in HIV patients.

Material and methods We performed an observational-retrospective study of the pharmacotherapeutic profile (all drugs) and clinical record (demographic and clinical data) of adult HIV patients on stable antiretroviral treatment (ART, at least 6 months) in a general teaching hospital. We defined polypharmacy as the use ≥5 drugs. To define the impact of DDIs we used the Lexi-Interact drug-interaction database; interactions categorised as D (consider treatment modification) or X (avoid combination) were analysed and further stratified into one of the following groups: Type 1 = ART + non-ART; Type 2 = two non-ARTs; Type 3 = two ARTs. One-way ANOVA was performed to compare interactions by group.

Results We evaluated 100 patients (female, 28; median age, 48 years; HCV co-infected, 43; HBV co-infected, 2; HCV&HBV co-infected, 7; adherence <95%, 9). There were 54 patients with polypharmacy (mean 7.5 ± 2.6 drugs/patient). ART profile was based on triple therapy with non-nucleosides (NN) in 65 patients, protease inhibitors (PIs) in 18, integrase inhibitor (II) 8 and other combinations in 9. Non-ART drugs most prescribed were statins (38 patients), benzodiazepines (at least one in 26 patients) and proton pump inhibitors (24 patients). We identified 123 DDIs in 43 patients, 83 (67.5%) classified as Category D or X (59 different drug pairs, Type 1: 2.17 DDIs/patient; Type 2: 0.62 DDIs/patient; Type 3: 0.07 DDIs/patient; p < 0.001). The ART drugs involved in DDIs were mainly PIs (34 pairs 57.6%) and non-ART drugs, mainly statins (9 pairs 15.2%).

Conclusion There is a medium-high level of polypharmacy and DDIs in our patients. Type 1 DDIs are significantly higher than the others, therefore greater attention to non-ART prescriptions is needed to ensure the safest drugs use in HIV patients.

References and/or acknowledgements No conflict of interest.