Two drugs that treat flu and HIV to be trialled on Covid-19 patients

Two antiviral drugs used to treat flu and HIV will be trialled on positive Covid-19 patients in the UK to see if they stop the coronavirus replicating

  • A total of 240 patients who tested positive for COVID-19 are being recruited  
  • Will take tablets over the course of seven days immediately after diagnosis 
  • They will be given either a placebo,  favipiravir, lopinavir/ritonavir or a combo 
  • The FLARE trial will determine if the antiviral drugs are useful in fighting the disease in early stages  

Two antiviral drugs are set to begin early human trials in London-based coronavirus patients.

A UCL-led study, dubbed the FLARE trial, will investigate the efficacy of favipiravir, which is used to treat the flu, and the cocktail of lopinavir/ritonavir which is given to HIV patients. 

Scientists are recruiting 240 participants between the ages of 18 and 70 who are based in the UK capital. 

To be eligible for the study participants must have tested positive for COVID-19 and be self-isolating.

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Scientists are recruiting 240 patients between the ages of 18 and 70 who are based in the UK capital. They will be given either a placebo, favipiravir or lopinavir/ritonavir

As part of the clinical trial the patients will receive a placebo, the flu medication, the HIV drugs or a combination of them both. 

All treatments will be taken as tablets over the course of seven days.   

Dr David Lowe, a UCL academic who is leading the trial, said: ‘This trial will test whether the antiviral drugs favipiravir or lopinavir/ritonavir, on their own or in combination, can reduce the level of the virus in people with early COVID-19 disease.

‘To maximise the potential benefit, we are treating patients with very early onset infection and are looking for the additional or synergistic effects of adding a second drug [favipiravir or lopinavir/ritonavir].

‘If we can find antivirals that decrease viral load early on, this might reduce the risk of transmission and later hospitalisation.’

The research project is hoping to determine if the treatment can interfere with how the coronavirus replicates once inside human cells. 

In the case of favipiravir the drug neutralises an enzyme that allows the virus to replicate genetic material, called polymerase. 

By removing this enzyme the virus can not replicate and therefore spread, and it is hoped this will improve a patient’s prognosis. 

A scientific paper published earlier this month found the drug inhibits coronavirus in hamsters. 

Favipiravir has also been the focus of a clinical trial in Japan run by Fujifilm, which owns the rights to the drug in the Asian country, under the brand name Avigan.

Japan approved Avigan as an emergency flu medicine in 2014 and the new research looked at its benefits for 156 late-stage COVID-19 patients.

Among people treated with the drug, symptoms improved after 11.9 days, versus 14.7 days for a placebo group. 

The drug has been approved in India and Russia to treat COVID-19. 

In July, India’s Glenmark Pharmaceuticals Ltd said its own version of favipiravir showed promise in a late-stage study of 150 patients with mild to moderate coronavirus infection.


Favipiravir is an antiviral drug which has been shown to be effective against regular flu. 

It has been approved as an influenza treatment in Japan, where it was discovered, since 2014.  

It stops viral replication by targeting an enzyme called polymerase which allows the genetic material of the virus to be cloned, a vital step in viral replication. 

The drug has been approved in India and Russia to treat COVID-19. 

Favipiravir inhibits 53 types of influenza viruses including seasonal strains A (H1N1), A (H3N2), and influenza B.

It is taken as a course of tablets.

A Japanese study found minor side effects associated with the drug seen in one in five COVID-19 patients it was sued to treat. 

These included diarrhea, nausea and vomiting. 

But it has been linked to birth defects in animals. 


The combination of lopinavir and ritonavir is used on HIV patients to prevent the virus developing into AIDS. 

Lopinavir and ritonavir are in a class of medications called protease inhibitors.

Protease inhibitors work by sticking to an enzyme on a virus which is vital to the virus reproducing.

By doing this it blocks the process the virus would normally use to clone itself and spread the infection further.

When lopinavir and ritonavir are taken together, ritonavir also helps to increase the amount of lopinavir in the body so that the medication will have a greater effect.

The combination comes as a tablet or a solution. It is usually taken twice a day.

HIV patients in the UK were prescribed either Kaltra or ritonavir alone around 1,400 times in 2018. 

Side effects can include nausea, vomiting, stomach upset, gas, headache, and trouble sleeping.

About 70 per cent of patients being treated by FabiFlu, another commercial name of  favipiravir, achieved ‘clinical cure’ by the fourth day of the study, the company claimed. In a control group this figure was just 45 per cent. 

There are currently 39 trials of favipiravir as a potential treatment for COVID-19 that have either been completed or are ongoing.

Lopinavir/ritonavir works in a different way to favipiravir and is called a protease inhibitor.

This too stops an enzyme working properly, but the enzyme it impacts is involved in creating proteins which are essential for the virus to grow. 

The two compound drug was an early participant in the RECOVERY trial but was found to be ineffective at treating late-stage COVID-19.  

Now, researchers are including it in FLARE to see if it is more effective in the early days of infection, hoping it can prevent the infection worsening. 

The study will also combine favipiravir with lopinavir/ritonavir to see if a prescription of both drugs is more effective. 

It remains unknown if treating COVID-19 patients with an antiviral in the early stages of infection is effective.

This study will help inform that and determine if antivirals can prevent serious symptoms, including hospitalisation and death. 

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