Singapore does not plan to use hydroxychloroquine to treat patients with Covid-19, even though the World Health Organisation (WHO) plans to restart the trial of this drug.
"There is no proper study that shows hydroxychloroquine works," said Associate Professor David Lye, director of the Infectious Disease Research and Training Office at the National Centre for Infectious Diseases (NCID).
The drug, originally developed to treat malaria, has been in the limelight, given the strong endorsement by US President Donald Trump, who claims he is taking it to stave off Covid-19.
A recent article in The Lancet journal - stating that the drug causes side effects and has no benefits based on information it claimed came from an international study - caused WHO to stop its trials of the drug.
But WHO said the trial will now restart following a retraction by the medical journal after the veracity of the paper was called into question.
But these decisions will not affect the treatment for Covid-19 patients in Singapore.
Prof Lye told The Straits Times: "There is increasing evidence that antimalarial drugs do not work. We have stopped using it at NCID for quite a while now."
He added that other trials of hydroxychloroquine have shown no benefit to Covid-19 patients but have caused side effects.
He said that a small number of patients here who were given the drug experienced gastrointestinal intolerance, such as nausea, vomiting, diarrhoea, and discomfort in the upper abdomen below the ribs.
The patients who were given the drug had milder forms of the Covid-19 infection.
Despite these reactions, the patients "still managed to complete the planned duration of treatment", Prof Lye said, but added: "There is no evidence that the use of the drug worked."
He said: "We will not be resuming the use of hydroxychloroquine because there are a few independent studies which show it does not work and has more side effects."
To date, there has been only one drug, remdesivir, that has been proven to work in patients with Covid-19, he said.
Remdesivir is a new, broad-spectrum antiviral medication that has been given emergency-use authorisation for Covid-19 patients by the Food and Drug Administration in the United States on May 1.
Last month, the NCID started trials of remdesivir, which was given intravenously to patients for five to 10 days.
The drug works by blocking an enzyme that is necessary for the Covid-19-causing virus to multiply.
The drug was developed by Gilead Sciences to treat hepatitis C. It has also been tested for treatment of Ebola and Marburg diseases. But it has been ineffective in treating these three diseases.