Evaluation of the effects of atazanavir-ritonavir on the pharmacokinetics of lumefantrine in patients living with HIV in Lagos University Teaching Hospital, South-Western Nigeria.

Purpose: Atazanavir-ritonavir (ATVr)-based antiretroviral therapy and artemether-lumefantrine (AL) are commonly used drugs for the treatment of human immune deficiency virus (HIV) infection and malaria respectively. However, interaction of both drugs, with Cytochrome P 3A4 (CYP 3A4) isoenzyme, may spawn clinically significant pharmacokinetic interactions. This study evaluated the effects of atazanavir-ritonavir on the pharmacokinetics of lumefantrine.

Method: In a case-control study, twenty participants having Plasmodium falciparum malaria were recruited and divided into two groups (ATVr-arm, n=10; and control-arm, n= 10). All the participants were administered six oral doses of AL 80-480 mg (Coartem). Thereafter, their blood samples were collected at different time intervals over seven days. The concentration of lumefantrine in each sample was quantified with high-performance liquid chromatography (HPLC) and used to determine its pharmacokinetic parameters which were compared between the test and control groups.

Results: ATVr increased the mean day 7 concentration of lumefantrine (ATVr 3847.09 ± 893.35 ng/mL, control 1374.53 ± 265.55 ng/mL, p = 0.016) and the area under its plasma concentration-time curve (ATVr 670529.57 ± 157172.93 ng.h/mL, control 447976.28 ± 80886.99 ng.h/mL, p = 0.224) by 179.88 % and 49.68 %, respectively, but decreased its mean maximum plasma drug concentration (Cmax) (ATVr 13725.70 ± 2658.44 ng/mL, control 15380.48 ± 2332.62 ng/mL, p = 0.645) by 10.76 %.

Conclusion: ATVr increased drug exposure and day 7 plasma concentration of lumefantrine. AL is therefore considered effective for the treatment of malaria in patients taking ATVr-based regimen. However, the safety associated with the interaction requires further elucidation.

Trial Registration: Clin ClinicalTrials.gov Identifier: NCT04531072, August 27, 2020. "Retrospectively registered".