A drug hailed by US president Donald Trump as a potential treatment for coronavirus appears to be safe but its effectiveness is still unknown, according to an Oxford-led research team.
Hydroxychloroquine is one of the medicines undergoing clinical trials to assess its safety and efficacy.
It is used as a treatment against malaria and certain autoimmune diseases such as rheumatoid arthritis.
More than 300 researchers from the Observational Health Data Sciences and Informatics (OHDSI) international community, including a team from the Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, have been investigating whether there are serious side effects from the drug.
The team analysed the medical history of 130,000 patients in Germany, the UK, and the United States who have previously taken the drug, in what researchers said was the largest investigation to date of its safety.
Dani Prieto-Alhambra, professor of pharmaco- and device epidemiology at the centre for statistics in medicine at Oxford who led the research, said it is too early to know how effective it is in treating Covid-19 and that further investigations are under way.
He said: “When administered at the doses used for current indications like rheumatoid arthritis, we have not detected any worrying side effects. We therefore think that it’s quite a safe medication in general.
“However, we lack data on its safety when used at higher doses, and it is too early to be able to understand its clinical effectiveness to treat Covid-19.
“Randomised controlled trials are under way that will define the anti-viral efficacy of this treatment, including research at Oxford using hydroxychloroquine on 3,000 high-risk patients to see if it can alleviate the worst of the symptoms.
“We’ll conduct a new study amongst Covid-19 patients when data starts accumulating.”
The European Medicines Agency has cautioned that hydroxychloroquine and chloroquine, which is also being investigated for its treatment potential, can have “serious side effects, especially at high doses or when combined with other medicines”.
The organisation on Wednesday issued a reminder that patients and healthcare professionals should only use the drugs as prescribed and in clinical trials or emergency use programmes.
Hydroxychloroquine was the subject of public sparring between Mr Trump and his government’s top infectious disease expert last month over whether it would work in coronavirus treatment.
Mr Trump said he disagreed with the notion that there is no magic drug for the coronavirus disease, despite Dr Anthony Fauci saying he could not make any “definitive statement” about it.
While Mr Trump said he agreed that it “it may work and it may not work”, he added: “I feel good about it”.
Meanwhile, preliminary results from a small study at a hospital in Bergamo provide “vital information” on an antibody which could be used on Covid-19 patients who have developed serious respiratory complications, an Italian professor said.
A third of the first 21 patients treated with siltuximab at the Papa Giovanni XXIII Hospital experienced a clinical improvement with a reduced need for oxygen support and 43% of patients saw their condition stabilise, the study involving UK-based Eusa Pharma concluded.
Professor Alessandro Rambaldi, study sponsor-investigator, said: “These initial data in siltuximab-treated patients provide vital information to guide decisions regarding appropriate use of siltuximab in both the real-world and new Covid-19 studies.”