Ensitrelvir Can Reverse COVID Smell and Taste Loss

In clinical trials, the experimental antiviral pill was effective in reducing the duration of COVID-related taste and smell symptoms.

Though the severity and incidence of COVID-19-related smell and taste loss appear to be dwindling, 2022 research suggests about 45% of COVID-19 patients experience these symptoms. While the antiviral drug molnupiravir has shown effectiveness in speeding up the recovery of these senses, it has largely been available only to the most vulnerable individuals.

Now, a new clinical trial conducted in Japan has revealed that the antiviral pill ensitrelvir can potentially reduce the duration of these bothersome mild-to-moderate COVID-19 symptoms. Moreover, this medication is not exclusively reserved for those at high risk of severe illness.

The trial results were presented on October 12th at IDWeek, a gathering of infectious disease specialists and epidemiologists in Boston, Massachusetts.

During the trial, investigators gave participants with mild-to-moderate COVID-19 symptoms either 125 or 250 milligrams (mg) of ensitrelvir or a placebo. At the onset of the study, 20% of the participants reported some degree of smell or taste loss.

After three days of ensitrelvir treatment, the number of individuals experiencing these symptoms in the ensitrelvir groups began to decrease more rapidly compared to the placebo group. By the seventh day, the percentage of participants with smell or taste loss was 39% lower in the group taking 250 mg of ensitrelvir than in the placebo group.

Three weeks after treatment initiation, all participants reported similar symptom scores. If further investigations yield comparable results, the new antiviral could help relieve smell and taste loss in people with the coronavirus disease and potentially prevent mild symptoms of long COVID, like smell loss.

While the pill received emergency use authorization in Japan in November 2022, it has yet to be approved in other countries. However, the FDA granted ensitrelvir Fast-Track designation to expedite the approval process in the United States. And as seen in the study, the outcomes in patients seem hopeful.

"As an investigator who has evaluated both clinical data and real-world experience with ensitrelvir, I am optimistic about its potential to become an important tool in managing the unpredictability of COVID-19," said Yohei Doi, M.D., Ph.D., a Professor of Medicine at Fujita Health University, Japan. "The new data presented at IDWeek regarding taste and smell symptoms offer another reason to have confidence in this investigational agent and its potential to be a meaningful treatment option for patients."