The UK’s Medicines and Healthcare products Regulatory Agency (MHRA) has suspended enrolment of participants for all Covid-19 clinical trials of hydroxychloroquine across the country over safety concerns.

No new volunteers will be recruited until further evidence suggests that these trials can be continued. The announcement is based on the Commission on Human Medicines’ review of data from each trial.

The Commission reviewed data from two different trials, including the UK’s RECOVERY trial, which showed no meaningful mortality benefit with hydroxychloroquine in hospitalised Covid-19 patients.

MHRA CEO Dr June Raine said: “We have told those conducting clinical trials using hydroxychloroquine to treat or prevent Covid-19 to suspend recruitment into their trials.

“Neither hydroxychloroquine nor chloroquine are licensed to treat COVID-19 related symptoms or to prevent infection.”

In the UK, hydroxychloroquine and chloroquine are indicated for the treatment of various diseases, including malaria, rheumatoid arthritis, lupus, amoebic hepatitis, and abscesses.

Raine added: “It is important to note that patients taking hydroxychloroquine and chloroquine to treat other health conditions can continue to do so, as advised by their healthcare professional, as the balance of benefits and risks remains favourable in the licensed uses.”

In May this year, the World Health Organization (WHO) temporarily suspended a clinical trial of hydroxychloroquine in Covid-19 patients over safety concerns.

The move comes after data from an observational study published in The Lancet journal revealed a higher mortality rate in patients treated with hydroxycholoroquine when given alone or with a macrolide.

WHO restarted the trial this month after the study’s Data Safety and Monitoring Committee reviewed trial data and recommended that it could continue without any modifications.