The Nucleoside/Nucleotide Analogs Tenofovir and Emtricitabine Are Inactive against SARS-CoV-2.

The urgent response to the COVID-19 pandemic required accelerated evaluation of many approved drugs as potential antiviral agents against the causative pathogen, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Using cell-based, biochemical, and modeling approaches, we studied the approved HIV-1 nucleoside/tide reverse transcriptase inhibitors (NRTIs) tenofovir (TFV) and emtricitabine (FTC), as well as prodrugs tenofovir alafenamide (TAF) and tenofovir disoproxilfumarate (TDF) for their antiviral effect against SARS-CoV-2. A comprehensive set of in vitro data indicates that TFV, TAF, TDF, and FTC are inactive against SARS-CoV-2. None of the NRTIs showed antiviral activity in SARS-CoV-2 infected A549-hACE2 cells or in primary normal human lung bronchial epithelial (NHBE) cells at concentrations up to 50 µM TAF, TDF, FTC, or 500 µM TFV. These results are corroborated by the low incorporation efficiency of respective NTP analogs by the SARS-CoV-2 RNA-dependent-RNA polymerase (RdRp), and lack of the RdRp inhibition. Structural modeling further demonstrated poor fitting of these NRTI active metabolites at the SARS-CoV-2 RdRp active site. Our data indicate that the HIV-1 NRTIs are unlikely direct-antivirals against SARS-CoV-2, and clinicians and researchers should exercise caution when exploring ideas of using these and other NRTIs to treat or prevent COVID-19.

Can remdesivir and its parent nucleoside GS-441524 be potential oral drugs? An in vitro and in vivo DMPK assessment.

Remdesivir (RDV) is the only US Food and Drug Administration (FDA)-approved drug for treating COVID-19. However, RDV can only be given by intravenous route, and there is a pressing medical need for oral antivirals. Significant evidence suggests that the role of the parent nucleoside GS-441524 in the clinical outcomes of RDV could be largely underestimated. We performed an in vitro and in vivo drug metabolism and pharmacokinetics (DMPK) assessment to examine the potential of RDV, and particularly GS-441524, as oral drugs. In our in vitro assessments, RDV exhibited prohibitively low stability in human liver microsomes (HLMs, t 1/2 = âˆ¼1 min), with the primary CYP-mediated metabolism being the mono-oxidation likely on the phosphoramidate moiety. This observation is poorly aligned with any potential oral use of RDV, though in the presence of cobicistat, the microsomal stability was drastically boosted to the level observed without enzyme cofactor NADPH. Conversely, GS-441524 showed excellent metabolic stability in human plasma and HLMs. In further in vivo studies in CD-1 mice, GS-441524 displayed a favorable oral bioavailability of 57%. Importantly, GS-441524 produced adequate drug exposure in the mice plasma and lung, and was effectively converted to the active triphosphate, suggesting that it could be a promising oral antiviral drug for treating COVID-19.

Preventive Efficacy of Tenofovir/Emtricitabine Against Severe Acute Respiratory Syndrome Coronavirus 2 Among Pre-Exposure Prophylaxis Users.

BACKGROUND: The preventive effect that tenofovir/emtricitabine (FTC) could have against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in human immunodeficiency virus-negative people is unknown. The objective of this study was to analyze the seroprevalence and clinical manifestations of COVID-19 among users of pre-exposure prophylaxis (PrEP), disoproxil fumarate/FTC (TDF/FTC), or tenofovir alafenamide (TAF)/FTC and to compare it to that of a control group. METHODS: An observational descriptive study of the seroprevalence of antibodies for SARS-CoV-2 among men who have sex with men and transgender women without use of PrEP (Group 1; n = 250) and PrEP users with TDF/FTC (n = 409) or TAF/FTC (n = 91) (Group 2; n = 500) was conducted from May11, 2020 to June 27, 2020. All participants were provided with a structured questionnaire that collected information on the variables to be analyzed, and testing for immunoglobulin G antibodies to SARS-CoV-2 (chemiluminescent microparticle immunoassay) was then carried out. RESULTS: The seroprevalence of SARS-CoV-2 was 9.2% (95% confidence interval [CI], 5.9-13.5) in the group without PrEP and 15.0% (95% CI, 12.0-18.4) in the group with PrEP (P = .026). Among users of TDF/FTC it was 14.7% (95% CI, 11.4-18.5), and in users of TAF/FTC it was 16.5% (95% CI, 9.5-25.7) (P = .661). In those who tested positive for SARS-CoV-2 and receiving PrEP, 57.4% manifested symptoms, compared with 78.3% in the control group (P = .070). In users of TDF/FTC the figure was 53.3% and in users of TAF/FTC the figure was 73.3% (P = .100). The duration of symptoms was 11.5 days in the control group, 9.0 days in PrEP users (P = .116), 7.0 days in users of TDF/FTC, and 13.0 days in users of TAF/FTC (P = .100). CONCLUSIONS: Users of PrEP, TDF/FTC, or TAF/FTC presented a higher seroprevalence to SARS-CoV-2 than the control group. No statistically significant differences were found in relation to clinical manifestations. The PrEP users should use the same prevention measures as those indicated for the general population.