The drugs hydroxychloroquine and chloroquine are being used experimentally to treat certain people with COVID-19, the disease caused by the new coronavirus, and they are also currently used to treat malaria and certain autoimmune diseases, like lupus and rheumatoid arthritis. But their newfound use in hospital settings that may be stressed and even chaotic, given to people who are severely ill, means that any safety concerns may be critically important. And one very large safety concern has emerged in a new study.
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Published online on the scientific server BioRxiv ahead of print, the study looked at the two drugs as possible cancer treatments in mice. Other studies have shown promise for the drugs in treating certain kinds of cancer, but the researchers in the new mouse study noticed one very troubling outcome in one particular safety test. When mice took either drug in combination with the diabetes drug metformin, 30% to 40% of them died quickly. Taking either drug by itself, or just metformin, had no such effect.
As a Forbes article on the new study notes, the researchers describe it as a “cautionary note” that doesn’t necessarily apply to humans. In fact, some small studies in the past have looked at people taking a combination of either hydroxychloroquine or chloroquine and metformin. In a 2014 study in India with 267 participants, researchers described the combination of hydroxychloroquine and metformin as “well tolerated.”
But the few small studies that have been done in the past don’t capture the context in which hydroxychloroquine and chloroquine are being used in the present pandemic — that is, in people who are severely ill and may already have damage to multiple organ systems. In this context, any toxicity in combination with metformin could outweigh the potential benefit of these drugs, and possibly even contribute to prolonged illness or death. That means doctors should be aware of at least the potential for toxicity, especially since metformin is widely prescribed and many people admitted to hospitals for COVID-19 have diabetes.
“While our observations in mice may not translate to toxicity in humans,“ the researchers conclude in the new study, “we hope that our report will be helpful to stimulate pharmacovigilance and monitoring of adverse drug reactions.”
Want to learn more about coronavirus and diabetes? Read “Coronavirus and Diabetes: What You Need to Know,” “Healthy Eating During Hard Times” and “Avoiding Coronavirus With Diabetes: Stock Up and Stay Home, CDC Says.”