The results of the findings from David A. Ostrov, Ph.D., of the University of Florida, were published in Pathogens in late November.
The report suggested that combining diphenhydramine — an antihistamine sold as Benadryl that is used for allergy symptoms — and lactoferrin — a protein found in cow and human milk — reduced replication of SARS-CoV-2 by 99% in lab tests on human lung and monkey cells.
"We found out why certain drugs are active against the virus that causes COVID-19," Ostrov told the University of Florida Health Newsroom. "Then, we found an antiviral combination that can be effective, economical and has a long history of safety."
Key to the research team’s findings was the focus on sigma receptors, which are proteins expressed in human cells. COVID-19 "hijacks" the body’s stress-response machinery, including these receptors, so it can replicate inside its host. Interfering with that process is key to inhibiting the virus’s potency, according to the researchers.
"We know the detailed mechanism of how certain drugs inhibit SARS-CoV-2 infection," Ostrov said.
The research, however, is preliminary, and Ostrov has cautioned against self-medicating with either diphenhydramine or lactoferrin for COVID-19 prevention. Lactoferrin is available commercially to treat stomach and intestinal ulcers but differs slightly from the type used in the experiment, Ostrov said.