Here's why doctors decided to study the ingredient in a popular heartburn med—and why no one should be making a drugstore run to stock up.

Scientists continue to look into potential treatments for COVID-19, and the latest to be touted is famotidine, which is the active ingredient in the popular over-the-counter heartburn medication Pepcid. 

Kevin Tracey, MD, president of Feinstein Institutes for Medical Research at Northwell Health in New York City, told Science that preliminary results of a clinical trial of famotidine could be ready in the next few weeks. The trials have been underway since April 7 at Northwell, one of the largest hospital systems in New York City. As of April 25, 1,174 patients—including 187 who were critically ill—have taken part. 

Dr. Tracey said that earlier in the outbreak, doctors who worked with coronavirus patients in Wuhan, China discovered that although one in five COVID-19 patients over the age of 80 died, many of those who survived had been taking heartburn meds. Studies on the Chinese patients have not yet been published, but the findings were enough to encourage US scientists to explore famotidine’s potential.  

Trialling an OTC drug intended to relieve heartburn might seem a bit out of left field, considering that COVID-19 is a disease affecting the lungs and airways. But Dr. Tracey pointed out in the Science interview that there are “many examples in the history of medicine where a drug that was designed for one purpose turns out to have an effect in another disease.” 

The case for trialling famotidine was bolstered by a computer model used by Florida-based Alchem Laboratories to compile a list of existing drugs that might fight coronavirus. Famotidine showed up near the top of the list, and the company received a $20.7 million contract to conduct the trial at Northwell from the US Biomedical Advanced Research and Development Authority (BARDA). 

According to Dr. Tracey, famotidine was flagged because—in theory—the drug is structured in a way that could prevent the coronavirus from replicating, in the same way that protease inhibitors, which are used to treat HIV, stop that virus from replicating.

“Famotidine is a histamine receptor blocker,” Solomon L. Lerer, MD, a gastroenterologist in Aventura, Florida, tells Health. Specifically, the compound blocks the H2 receptors that play a role in producing acid in the stomach, which can lead to heartburn, a main symptom of gastroesophageal reflux disease (GERD). Famotidine is considered a relatively safe drug, Dr. Lerer adds, but side effects can include diarrhea, muscle aches, and headaches.  

“Famotidine is most commonly used to treat gastroesophageal reflux disease,” Abraham Khan, MD, director of the Center for Esophageal Diseases at NYU Langone Health, tells Health. “Often, it works best in patients with mild GERD symptoms that do not need a daily stronger acid suppressive medication, such as a proton pump inhibitor (PPI).”

Dr. Khan says that “it is not intuitive to think that famotidine would be a successful treatment for COVID-19 patients.” However, based on the limited retrospective evidence on outcomes made available so far, as well as the possibility that the drug may bind to a viral enzyme to interfere with its replication, he believes it’s worth an official trial study to see if it can be a treatment option for COVID-19.

“The evidence from China is anecdotal, and a double-blind study is needed to really determine the effectiveness of famotidine," adds Dr. Lerer.

The patients participating in the clinical trial at Northwell Health include a group who are also taking the anti-malarial drug hydroxychloroquine, as well as patients who are on hydroxychloroquine only. Hundreds of patients treated early on in the COVID-19 outbreak are also part of the trial.

Hydroxychloroquine is the drug hailed as a “game changer” by President Trump in a coronavirus task force briefing on March 20. However, preliminary results from a study sponsored by the New York State Department of Health, which looked at about 600 patients at 22 hospitals in the greater New York City area, suggest that hydroxychloroquine "didn't really have much of an effect on the recovery rate,” according to New York Governor Andrew Cuomo, as reported by CNN

The same discouraging result could come out of the famotidine study. Keep in mind that this is a trial, and no drug treatment—famotidine or something else—will be approved to treat COVID-19 anytime soon. 

In the meantime, Dr. Lerer warns that people should absolutely not rush out to buy the drug from their local drugstore. “It's important to be aware that in this current Northwell study, patients are taking mega doses of famotidine intravenously and are not taking pills orally. There is always a possibility that mega doses of any drug can have potential negative long-term side effects,” he says. And if the general public starts stockpiling Pepcid, heartburn patients who really need it could suffer.

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDCWHO, and their local public health department as resources.

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