Why is an old antacid, Pepcid (famotidine) in the news for COVID-19 treatment?

Currently there is only anecdotal data for famotidine’s potential benefit in COVID19 patients. Northwell hospital in New York is conducting a trial that is enrolling patients. This trial’s treatment arm will include hydroxychloroquine + famotidine vs previously treated COVID19 patients. The researchers recognize this is not an ideal trial design but want to get more data. So far the early mention of famotidine is from the use of  the drug by one of the researcher’s sister and friends who showed a reduction in symptoms.