Treatment Strategies: Antiviral Treatments
As described briefly earlier, a number of studies have focused on
repurposing existingantiviraltherapies, particularly those showing prior
effectiveness against SARS-CoV and MERS-CoV. The most popular
exploratory antiviral is the combination of lopinavir / ritonavir which
appears in 34 investigational studies (Table 1: antivirals). Both drugs
act as protease inhibitors, and are commonly used in HIV-1 management
[57]. However, due to the rapid catabolism by the cytochrome P450
enzyme system (specifically 3A4 isoenzyme) [57], lopinavir has
inadequate oral bioavailability for substantial therapeutic operation.
Ritonavir is thus administered concomitantly to suppress this, greatly
improving lopinavir’s half-life. In 2004, the efficacy of lopinavir /
ritonavir against SARS-CoV was investigated and found to be effective
compared with a historical control[58].Nevertheless, efficacy was
not seen in a randomized open-label study (lopinavir / ritonavir versus
standard care) in 199 COVID-19 patients (Clinical Trial Number:
ChiCTR2000029308, recruitment target reported as 160 registry
participants; Table 1). There was no majorgain in the overall mortality
or viral load [59]. Remdesivir is a novel antiviral analog
nucleotide, originally developed to treat the Ebola and Marburg viruses
[10, 60]. Nonetheless, it does have efficacy against a number of
pathogenic viruses, including both in vitro and in vivo models of
SARS-CoV and MERS-CoV[10, 61]. Subsequent diagnosis of the first
COVID-19 case and subsequent recovery in the U.S.[11], this molecule
was of great interest. A number of globally reported trials are
currently underway to examine theefficacy of COVID-19 (Table 1:
Antivirals). Many other antiviral medications, especially those with
action against various influenza subtypes and other RNA viruses are
being studied. Which are favipiravir (T-705, Avigan), umifenovir
(Arbidol), triazavirin (TZV), and marboxil (Xofluza) baloxavir. Most
trials concentrate on medications widely used to treat RNA viruses, such
as HCV and HIV. Which include danoprevir / ritonavir, azvudine,
ledipasvir / sofosbuvir, sofosbuvir / daclatasvir, darunavir /
cobicistat and emtricitabine / tenofovir (Table 1: antivirals).
Additionally, 26 studies examine the efficacy of antiviral
interferon-based drugs, and interestingly often look at various routes
of administration (e.g., nasal).