Point-of-care assays using urine and blood samples may help to improve adherence to antiretroviral therapy (ART) in people with HIV, according to the results of a study published in AIDS Research and Human Retroviruses. However, developing point-of-care assays will need to account for sample type, since the ability to detect high concentrations of different drugs used in ART varied by sample type.
Researchers collected urine, dried blood spots, and buccal swabs from 35 HIV-negative men who took a single dose of emtricitabine, tenofovir alafenamide, elvitegravir, and cobicistat (Genvoya®, Gilead) and darunavir. Samples were collected between 2 and 96 hours following the single dose and measured using high-performance liquid chromatography-tandem mass spectrometry. Drug concentrations in the 3 specimens were also compared with plasma drug concentrations to determine the feasibility of developing point-of-care assays for antiretroviral drugs.
Although concentrations of emtricitabine were detectable in all 3 samples after 2 hours, urine samples were found to be the most effective. More than 90% of urine samples demonstrated a high concentration of emtricitabine up to 48 hours after dosing, with emtricitabine remaining detectable in more than 50% of urine samples at 96 hours. Dried blood spot samples were reliable up to 24 hours. Buccal swabs were the least reliable, with emtricitabine remaining detectable in only 50% of specimens within 24 hours.
Although tenofovir alafenamide was detectable in only 67% (10 out of 15) of urine samples at 2 hours, concentrations of tenofovir were detectable in more than 90% of urine samples up to 24 hours after dosing, with tenofovir concentrations remaining detectable up to 96 hours after dosing in more than 50% of samples.
Dried blood spot samples were the best for detecting elvitegravir, with drug concentrations detected up to 24 hours after dosing. Elvitegravir was detectable in less than 50% of urine and buccal swab samples at any time point.
Although cobicistat was detectable in more than 50% of all 3 sample types up to 8 hours after dosing, it was undetectable in more than half the samples after 24 hours.
Similar to emtricitabine, darunavir was detectable in all 3 sample types after 2 hours. Concentrations of darunavir were detectable in more than half of urine and buccal swab specimens 24 hours after dosing and in more than half of dried blood spot samples after 72 hours.
Emtricitabine and darunavir concentrations correlated with plasma drug concentrations in urine (r=0.510 and r=0.555, respectively; P <.001) and dried blood spots (r=0.941 and r=0.917, respectively; P <.001). Elvitegravir concentrations correlated with plasma drug concentrations in dried blood spot samples (r=0.867; P <.001).
The findings from this study demonstrate that urine and blood samples hold more promise in developing point-of-care tests for ART than buccal swabs. However, there were numerous limitations to this study that warrant further research. This study did not measure hydration or body mass index. It included participants who only received a single dose of ART rather than continuous dosing. Also, the study did not include newer drugs that do not require coadministration.
Haaland RE, Martin A, Mengesha M, et al. Evaluation of antiretroviral drug concentrations in minimally invasive specimens for potential development of point of care drug assays. AIDS Res Hum Retroviruses. Published online February 16, 2021. doi:10.1089/AID.2020.0187