Male participants taking tenofovir-emtricitabine (TDF/FTC) will provide semen and blood samples which will be analyzed to better understand the pharmacology of antiretroviral therapy in the male genital tract.
8 HIV positive men taking TDF/FTC and 8 HIV negative men taking TDF/FTC as pre-exposure prophylaxis will provide multiple semen and blood samples during a 48-hour inpatient visit. 8 HIV positive men taking TAF (tenofovir alafenamide) will provide multiple semen and blood samples during a 48-hour inpatient visit. Participants will take part in the study for approximately two months. After the screening visit, there is one 2 day overnight visit for intensive PK/PD (pharmacokinetic/pharmacodynamic) sampling. The investigators will study drug concentrations and intracellular endogenous nucleotide concentrations (dATP and dCTP) in seminal plasma and (where appropriate) seminal cells. Samples will be analyzed through the use of novel laboratory methods to determine the seminal plasma and seminal cell concentrations of tenofovir and emtricitabine. New technologies will be used to better understand compartmental and intracellular antiretroviral pharmacology of nucleoside/tide reverse transcriptase inhibitors. Pharmacokinetic modeling will be used to estimate the primary outcomes.
Study Type
OBSERVATIONAL
Enrollment
26
University of North Carolina
Chapel Hill, North Carolina, United States
Semen Clearance (CL) of Tenofovir
Samples will be analyzed for drug concentrations at the following time points post dose: 3, 6, 9, 12, 18 and 24 hours, and used to estimate clearance from semen from a 300mg dose of tenofovir.
Time frame: Samples collected at 3, 6, 9, 12, 18 and 24 hours post-dose
Semen Clearance (CL) of Emtricitabine
Samples will be analyzed for drug concentration at the following time points post dose: 3, 6, 9, 12, 18 and 24 hours, and used to estimate clearance from semen from a 200mg dose of emtricitabine.
Time frame: Samples collected at 3, 6, 9, 12, 18 and 24 hours post-dose
Semen Clearance (CL) of Tenofovir Diphosphate
Samples will be analyzed for drug concentration at the following time points post dose: 3, 6, 9, 12, 18 and 24 hours, and used to estimate the clearance of tenofovir diphosphate, an intracellular metabolite of tenofovir, from seminal mononuclear cells, following a 300mg dose of tenofovir.
Time frame: Samples collected at 3, 6, 9, 12, 18 and 24 hours post-dose
Semen Clearance (CL) of Emtricitabine Triphosphate
Samples will be analyzed for drug concentration at the following time points post dose: 3, 6, 9, 12, 18 and 24 hours, and used to estimate the clearance of emtricitabine triphosphate, an intracellular metabolite of emtricitabine, from seminal mononuclear cells, following a 200mg dose of emtricitabine.
Time frame: Samples collected at 3, 6, 9, 12, 18 and 24 hours post-dose
Peripheral Blood Mononuclear Cell (PBMC) Clearance (CL) of Tenofovir Diphosphate
Samples will be analyzed for drug concentration at the following time points post dose: 3, 6, 9, 12, 18 and 24 hours, and used to estimate the clearance of tenofovir diphosphate, an intracellular metabolite of tenofovir, from peripheral blood mononuclear cells, following a 300mg dose of tenofovir.
Time frame: Samples collected at 3, 6, 9, 12, 18 and 24 hours post-dose
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Peripheral Blood Mononuclear Cell (PBMC) Clearance (CL) of Emtricitabine Triphosphate
Samples will be analyzed for drug concentration at the following time points post dose: 3, 6, 9, 12, 18 and 24 hours, and used to estimate the clearance of emtricitabine triphosphate, an intracellular metabolite of emtricitabine, from peripheral blood mononuclear cells, following a 200mg dose of emtricitabine.
Time frame: Samples collected at 3, 6, 9, 12, 18 and 24 hours post-dose
Tenofovir Diphosphate (TFVdp)/Deoxyadenosine Triphosphate (dATP) Ratio in Seminal Mononuclear Cells
dATP concentrations in seminal mononuclear cells will be measured and compared to tenofovir diphosphate concentrations, using a ratio, and summarized descriptively for each subject, as well as across subjects. As the six seminal cell samples collected per man were pooled for analysis due to low cell recovery, a single ratio value per participant was calculated and summarized by study arm.
Time frame: Average concentration in a 24 hour dosing interval
Emtricitabine Triphosphate (FTCtp)/Deoxyadenosine Triphosphate (dCTP) Ratio in Seminal Mononuclear Cells
dCTP concentrations in seminal mononuclear cells will be measured and compared to emtricitabine triphosphate concentrations, using a ratio, and summarized descriptively for each subject, as well as across subjects. As the six seminal cell samples collected per man were pooled for analysis due to low cell recovery, a single ratio value per participant was calculated and summarized by study arm.
Time frame: Average concentration in a 24 hour dosing interval