While HCQ is used to prevent or treat malaria, Remdesivir is sold as an antiviral drug.
The researchers from Oslo university hospital and colleagues randomly assigned 181 hospitalised patients in 23 hospitals in Norway to receive Remdesivir, HCQ, or standard of care.
The study, published in the journal Annals of Internal Medicine, evaluated the effects of the two drugs on all-cause, in-hospital mortality, the degree of respiratory failure and inflammation, and viral clearance in the oropharynx.
The ‘NOR-Solidarity‘ study, an independent, add-on, randomised controlled trial to the World Health Organization (WHO) Solidarity trial, found that neither Remdesivir nor HCQ affected viral clearance in hospitalised patients with Covid-19.
The WHO solidarity trial had shown no effect of Remdesivir or HCQ on mortality but did not assess antiviral effects of these drugs.
The latest study found no significant differences between treatment groups on mortality during hospitalisation.
The researchers also found that Remdesivir and HCQ did not affect the degree of respiratory failure or inflammation.
There was a significant decrease in SARS-CoV-2 load in the oropharynx during the first week in all treatment groups, with similar decreases in 10-day viral loads.
The lack of antiviral effect with Remdesivir and HCQ remained consistent despite patient age, symptom duration, degree of viral load, and presence of antibodies against SARS-CoV-2.
The researchers noted that overall mortality in NOR-Solidarity was lower than in the WHO-Solidarity trial.
This could be due to early lockdown policies in Norway during the initial phase of the pandemic, reducing pressure on hospitals and health care systems, the researchers said.
Norway also had lower rates of comorbid conditions such as diabetes and chronic heart disease, they said.
Based on their findings, the researchers question the antiviral potential of Remdesivir and HCQ.