GENVOYA(elvitegravir, cobicistat, emtricitabine, and tenofovir alafenamide)tablets(十九)
LINICAL PHARMACOLOGY
12.1 Mechanism of Action
GENVOYA is a fixed-dose combination of antiretroviral drugs elvitegravir (plus the CYP3A inhibitor cobicistat), emtricitabine, and tenofovir alafenamide [see MICROBIOLOGY (12.4)].
12.2 Pharmacodynamics
Cardiac Electrophysiology
Thorough QT studies have been conducted for elvitegravir, cobicistat, and TAF. The effect of emtricitabine or the combination regimen GENVOYA on the QT interval is not known.
Elvitegravir: In a thorough QT/QTc study in 126 healthy subjects, elvitegravir (coadministered with 100 mg ritonavir) 125 mg and 250 mg (0.83 and 1.67 times the dose in GENVOYA) did not affect the QT/QTc interval and did not prolong the PR interval.
Cobicistat: In a thorough QT/QTc study in 48 healthy subjects, a single dose of cobicistat 250 mg and 400 mg (1.67 and 2.67 times the dose in GENVOYA) did not affect the QT/QTc interval. Prolongation of the PR interval was noted in subjects receiving cobicistat. The maximum mean (95% upper confidence bound) difference in PR from placebo after baseline-correction was 9.5 (12.1) msec for the 250 mg cobicistat dose and 20.2 (22.8) for the 400 mg cobicistat dose. Because the 150 mg cobicistat dose used in the GENVOYA fixed-dose combination tablet is lower than the lowest dose studied in the thorough QT study, it is unlikely that treatment with GENVOYA will result in clinically relevant PR prolongation.
Tenofovir Alafenamide (TAF): In a thorough QT/QTc study in 48 healthy subjects, TAF at the therapeutic dose or at a supratherapeutic dose approximately 5 times the recommended therapeutic dose did not affect the QT/QTc interval and did not prolong the PR interval.
Effects on Serum Creatinine
The effect of cobicistat on serum creatinine was investigated in a Phase 1 study in subjects with an eGFR of at least 80 mL per minute (N=18) and with an eGFR of 50 to 79 mL per minute (N=12). A statistically significant change of eGFRCG from baseline was observed after 7 days of treatment with cobicistat 150 mg among subjects with an eGFR of at least 80 mL per minute (−9.9 ± 13.1 mL/min) and subjects with an eGFR of 50 to 79 mL per minute (−11.9 ± 7.0 mL per minute). These decreases in eGFRCG were reversible after cobicistat was discontinued. The actual glomerular filtration rate, as determined by the clearance of probe drug iohexol, was not altered from baseline following treatment of cobicistat among subjects with an eGFR of at least 50 mL per minute, indicating cobicistat inhibits tubular secretion of creatinine, reflected as a reduction in eGFRCG, without affecting the actual glomerular filtration rate.
12.3 Pharmacokinetics
Absorption, Distribution, Metabolism, and Excretion
The pharmacokinetic (PK) properties of the components of GENVOYA are provided in Table 6. The multiple dose PK parameters of elvitegravir, cobicistat, emtricitabine, TAF and its metabolite tenofovir are provided in Table 7.
Table 6 Pharmacokinetic Properties of the Components of GENVOYA
Elvitegravir Cobicistat Emtricitabine TAF
PBMCs = peripheral blood mononuclear cells; CES1 = carboxylesterase 1.
* Values refer to geometric mean ratio in AUC [fed / fasted] and (90% confidence interval). Elvitegravir light meal=~373 kcal, 20% fat; GENVOYA light meal=~400 kcal, 20% fat; elvitegravir and GENVOYA high fat meal=~800 kcal, 50% fat. Based on the effect of food on elvitegravir, GENVOYA should be taken with food. † In vivo, TAF is hydrolyz |
