Metformin Warning: Study Points to Toxicity with Coronavirus Treatments

Published on April 14, 2020 by Sandy Liebhard

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A new study suggests some potential coronavirus treatments may prove toxic when administered to patients in combination with metformin.

About Hydroxychloroquine and Chloroquine

The drugs in question —  hydroxychloroquine (HCQ) and chloroquine (CQ) – are typically used to treat malaria. But both have been repeatedly touted by President Trump as possible coronavirus treatments, largely due to anecdotal evidence suggesting they might be effective against COVID-19. Several clinical trials are now underway to determine if this is, in fact, the case.

Despite the President’s considerable enthusiasm, many medical experts remain reluctant – at least for now — to recommend hydroxychloroquine and chloroquine as coronavirus treatments, citing scant evidence of their effectiveness, as well as a small but potentially deadly risk of cardiac toxicity and other dangerous side effects.

What the Study Found

These new findings were  published online on scientific pre-print server BioRxiv and indicated that between 30% to 40% of mice treated with hydroxychloroquine or chloroquine in combination with metformin had died. By contrast, there were no deaths recorded study’s single treatment group.

“We have seen the escalating interest in HCQ for COVID-19, not only for therapy, but now increasingly for prophylaxis following exposure to an infected family member or a patient,” the authors wrote. “Because this drug is likely to be used in spades – either as part of a clinical trial or what we call “off label” – we wanted to get this information out at the earliest opportunity, so that physicians treating COVID-19 patients are at least aware of this potential drug interaction.”

Last week, the U.S. Centers for Disease Control reported that coronavirus patients with certain underlying conditions – including diabetes – were more likely to be hospitalized or require care in the ICU. However, the report did not include any information on medications – including metformin – these patients might have been taking to treat those underlying conditions.

About Metformin: Recent Recalls and Warnings

Metformin is the most widely-used oral medication indicated for adults with Type 2 diabetes.

The drug also made news late last year, when regulators in Singapore ordered a recall for three metformin lots that might contain excessive levels of Nitrosodimethylamine (NDMA), a probable human carcinogen.

The Singapore metformin recalls prompted the U.S. Food & Drug Administration (FDA) to begin its own investigation. Although those tests did detect NDMA in some metformin tablets, the agency insisted the levels were far below its recommended daily limit of 96 nanograms, and thus posed no health risk.

Just last month, however, the online pharmacy Valisure announced that its own tests had detected excessive levels of NDMA in 16 of 38 metformin samples tested. The highest amounts were found in Amneal Pharmaceutical’s metformin, which in some cases contained as much as 16-times the FDA’s recommended daily limits. Several companies’ metformin contained more than 10 times the limit.

Valisure has requested that the affected metformin lots be recalled, but the FDA has yet to respond to the company’s petition.