A combination of two existing drugs is highly effective against SARS-CoV-2 in cell cultures, researchers in Norway and Estonia have found.
In a separate experiment, the researchers used the same cell cultures to show that convalescent blood plasma may be ineffective if the patient donated it 2 months after receiving a diagnosis of COVID-19. This is the respiratory disease that SARS-CoV-2 causes.
On June 16, 2020, scientists at the University of Oxford in the United Kingdom announced the first drug proven to reduce mortality in people with severe COVID-19.
The breakthrough, which the team will report in the journal Nature, means that doctors can immediately start treating hospitalized patients with dexamethasone. This is a cheap, readily available steroid that has been in widespread use for decades.
Drugs with a proven safety record, such as dexamethasone, have a clear advantage over novel treatments and vaccines; after a relatively swift clinical trial, national drug regulators can immediately approve their use.
Research by scientists in Norway and Estonia has now identified two more drugs that regulators could potentially fast-track in this way.
The drugs are antivirals that already have approval to treat other infections. Like dexamethasone, researchers would need to test their efficacy against SARS-CoV-2 in people with the virus.
In the new study, a group of scientists from the Norwegian University of Science and Technology in Trondheim collaborated with scientists at the University of Tartu in Estonia.
They first screened 12 human and animal cell lines to determine which was the most susceptible to the virus.
They identified one cell line called Vero-E6, which they extracted from African green monkeys, then they exposed cultures of these cells to SARS-CoV-2 plus varying concentrations of 136 antiviral drugs.
The drugs were from a database of broad-spectrum antiviral agents (BSAAs), which the same research team set up earlier in 2020. BSAAs are drugs that have passed a clinical safety trial and that work against two or more families of viruses.
After 72 hours, the researchers counted how many cells were still alive in each culture dish. This allowed them to narrow down the field to six drugs that were the most effective at rescuing cells from SARS-CoV-2.
The six antivirals that were active against the virus were:
- salinomycin
- nelfinavir
- amodiaquine
- obatoclax
- emetine
- homoharringtonine
Next, the scientists repeated the process us