Famotidine is a common heartburn medication, often sold under the name Pepcid. At Northwell Health, a study is examining if famotidine combined with hydroxychloroquine can be used to treat patients infected with coronavirus.

"The molecule fit perfectly into a particular receptor, and it functioned as what they call a protease inhibitor, which is a molecule that prohibits from the virus reproducing itself," said Dr. David Battinelli, senior vice president and chief medical officer at Northwell Health.

The trial began two weeks ago. Nearly 200 patients are enrolled, and there are hopes of adding at least 1,000 more.

Participants will either receive hydroxychloroquine alone or the antimalarial drug plus famotidine. The famotidine dosage is nine times the dose used to treat heartburn.

Hydroxychloroquine has been talked up by President Donald Trump, but so far, no American studies have shown it to be an effective treatment for coronavirus. It is part of the Northwell trial because so many patients have been receiving it.

"If they are good results, that will be great, but sometimes, things don't work out. But we want to make sure that we know the facts so that we can either abandon certain things or move on with other things," Battinelli said. "Right now, the big problem with treating this virus is, we have a lot of anecdotal reports of people thinking things work without a lot of clear data."

The idea for the trial came from observations out of China. An American doctor working with patients in Wuhan noticed that patients who had been taking the heartburn drug seemed to do better than others fighting the virus.

"It had been noticed when treating patients in China that for whatever reason, patients who came into the hospital already taking famotidine because they had acid reflux disease did better than patients who were not taking the medication," Battinelli said.

The trial is only offered to patients who are admitted to the hospital with the coronavirus. Results could be available in four weeks.

Researchers say people should not take the mega doses of famotidine themselves because the treatment is unproven and is being administered in the trial intravenously.