Another study casts doubt on the malaria drugs touted by President Donald Trump as potential game-changers against Covid-19.
The drugs, chloroquine and hydroxychloroquine, are also used for lupus and rheumatoid arthritis. But Trump and others have promoted their use as treatments for the coronavirus that has sickened millions around the world.
Now, a research review in the May issue of the FASEB Journal questions their usefulness for Covid-19, saying human studies have not replicated results seen in laboratory research. The drugs may also dampen immune defences needed to quell the coronavirus.
Those findings come on the heels of a US Food and Drug Administration (FDA) warning that the drugs are too dangerous for general use. According to the FDA, studies have shown that chloroquine and hydroxychloroquine may trigger potentially fatal heart rhythm problems in Covid-19 patients.
Drugs only work in lab experiments
For the new study, Dr Mark Poznansky, an associate professor at Harvard Medical School, and colleagues reviewed anecdotal reports and clinical trials.
"When I went on service a few weeks ago in the ICUs of Massachusetts General Hospital as an infectious disease attending physician, it was evident to me and my colleagues that there were both risks and benefits of the widespread initial use of hydroxychloroquine in the context of Covid-19 infection," said Poznansky, who is director of the hospital's Vaccine and Immunotherapy Center.
"This was based on seeing patients who, for whatever reason, appeared to be doing poorly despite the use of this medication," he said in a journal news release.
Poznansky's team said scientists were optimistic about the use of these drugs because they reduced the ability of cells to be infected – but only in lab experiments, not in patients.
The hope for these drugs didn't take their immunosuppressive action into account. It's this ability that makes them an effective treatment for rheumatoid arthritis and lupus. However, Poznansky's group thinks chloroquine and hydroxychloroquine inhibit immune reactions essential to defending against the virus.
Furthermore, both drugs have failed in other respiratory virus outbreaks, such as influenza, the researchers note.
Cardiac side effects
Neither chloroquine nor hydroxychloroquine should be used based on the reports of lab experiments rather than studies with patients, the authors say.
Moreover, clinical trial results have led to a diminishing view of their use for Covid-19, they note.
"We chose to dive into this important matter in an expedited manner to create a science-based awareness of this subject," Poznansky said.
"Beyond the known cardiac side effects of this drug, we aimed to reveal those aspects of the anti-viral and immune-modulatory activities of hydroxychloroquine that could potentially help or, as importantly, impair a patient's response to the virus," he explained.
The goal, he said, "was to help physicians make data-informed decisions about how to use this drug for patients with Covid-19 infection within carefully designed clinical trials."
The FASEB Journal is published by the Federation of the American Societies for Experimental Biology.