A clinical trial was unable to prove the efficacy of the antiparasitic medicine ivermectin against coronavirus variants, according to Japanese drugmaker Kowa Co., which has indicated that it will no longer seek approval for the drug as a COVID-19 treatment.

The Nagoya-based pharmaceutical and trading company announced the results of a randomized, double-blind, international clinical trial on Sept. 26. In the trial, 1,030 patients with mild COVID-19 were orally administered the drug daily for three days and then compared to others given a placebo.

Ivermectin was found to be safe and few people given the drug developed severe symptoms, Kowa said. But both the group given the drug and the one administered a placebo saw improvements in symptoms, meaning the trial did not show the drug’s efficacy over the placebo as a COVID-19 treatment.

“In order to better understand the drug’s potential, Kowa will continue analyzing the data in detail and from a variety of perspectives," the firm said in a press release.

Ivermectin is an antibiotic medication used in the treatment of parasitic diseases, such as lymphatic filariasis, strongyloidiasis and psoriasis. It was discovered by biochemist Satoshi Omura, professor emeritus of Kitasato University, for which he won the Nobel Prize in physiology or medicine in 2015.

While a large-scale study conducted in Brazil concluded in March that treatment with the drug's did not prevent hospitalization for patients with COVID-19 symptoms, social media remains abuzz with claims of ivermectin’s ability to cure those infected with coronavirus strains. The U.S. Food and Drug Administration has even weighed in to say that people should not use the drug to treat or prevent the disease in either humans or animals.