The drug touted by the US President Donald Trump as a possible line of treatment against the coronavirus comes with severe warnings in China and can kill in dosages as little as two grams.
China, where the deadly pathogen first emerged in December, recommended the decades-old malaria drug chloroquine to treat infected patients in guidelines issued in February after seeing encouraging results in clinical trials. But within days, it cautioned doctors and health officials about the drug's lethal side effects and rolled back its usage.
This came after local media reported that a Wuhan Institute of Virology study found that the drug can kill an adult just dosed at twice the daily amount recommended for treatment, which is one gram.
As the drug hasn't been approved by the US Food And Drug Administration to treat the disease known as Covid-19, the Chinese experience may be useful as the American regulator studies the medication which has been endorsed by Trump as well as Tesla Inc. chief executive officer Elon Musk.
The pandemic, which has sickened more than 235,000 globally and killed over 9,800 people, has triggered growing anxiety across the U.S. as states say they lack testing kits and medical equipment. California instituted a state-wide lockdown on Thursday to slow the outbreak.
Chloroquine was among the first group of therapies Chinese scientists identified as being effective in curbing the new coronavirus. Clinical trials on about 130 patients demonstrated the drug's ability to reduce the severity of the illness and speed up virus clearance, according to China's Ministry of Sciences and Technology.
Chroloquine phosphate was officially recommended on Feb. 19 in the Covid-19 treatment guidelines published by China's National Health Commission, along with a few other drugs such as AbbVie Inc.'s Kaletra and flu drug arbidol as antiviral treatments for patients. The commission recommended no more than a 10-day course of chloroquine for adult patients at 500mg - half a gram - twice a day.
The search for new drugs for coronavirus faces long odds
As hundreds of clinical trials are launched to study potential Covid-19 treatments, stocks of drugmakers and biotechnology companies have racked up big gains on the hope that the industry will see a windfall. But the history of previous viral outbreaks like Ebola and Zika show little success in producing viable treatments. Some potential drugs were developed only after the epidemics already waned through containment measures.