TOKYO: Oral antiviral drugs are attracting attention as possible game changers in the battle against the novel coronavirus.
Major US drugmaker Merck & Co. recently sought an emergency use authorization from the US Food and Drug Administration for molnupiravir, an oral antiviral drug now under development. The company is likely to file for approval from Japan’s health ministry soon.
The Japanese government plans to put oral COVID-19 drugs into practical use by the end of the year. Among Japanese drugmakers, Shionogi & Co. is accelerating the development of its orally taken COVID-19 drug.
“If mildly ill COVID-19 patients can prevent their symptoms from becoming worse by taking oral drugs, the strain on the medical system would be eased,” Aichi Medical University professor Hiroshige Mikamo said.
Japanese Prime Minister Fumio Kishida has also pinned high hopes on oral drugs, saying that they “might become a key tool in the fight against the novel coronavirus.”
Molnupiravir, which is being developed jointly by Merck and US firm Ridgeback Biotherapeutics, is designed to prevent coronavirus symptoms from worsening by blocking the functioning of RNA polymerase, an enzyme that is needed for the proliferation of the virus.
In an international clinical trial for mildly and moderately ill COVID-19 patients, molnupiravir reduced the risk of hospitalization and death by about half. There were no deaths among people who received the drug in the trial.
Merck has already signed a contract with the US government for the supply of the drug. It is in negotiations with the Japanese government on a supply deal.
Shionogi’s potential antiviral drug, S-217622, is for blocking 3CL protease, another enzyme for helping the multiplication of the virus.
The company started the final phase of its clinical trial for the drug in September.
Shionogi President Isao Teshirogi has said that the company aims to make it available for at least one million people by the end of March 2022.
Swiss drug giant Roche and Atea Pharmaceuticals of the United States are developing AT-527, with the results of the final phase of the clinical trial for the drug expected to become available by the end of the year. The companies plan to seek approval in Japan next year.
US pharmaceutical giant Pfizer Inc. is also conducting clinical trials for its oral antiviral drug across the world.
Influenza drug Avigan, which was expected to play an important role in the fight against COVID-19 in the earlier stage of the pandemic, is a so-called RNA polymerase inhibitor, like molnupiravir.
Tokyo-based Fujifilm Toyama Chemical Co., the Fujifilm Holdings Corp. subsidiary that developed Avigan, is conducting an additional clinical trial for the drug, after the Japanese health ministry failed to clearly confirm its effectiveness against the coronavirus.
In Japan, ivermectin, an antiparasitic drug, has been used in treating coronavirus patients at the discretion of doctors although it has yet to win regulatory approval for use against COVID-19.
As its effectiveness remains to be confirmed, drugmaker Kowa Co., based in Nagoya, the capital of Aichi Prefecture, central Japan, is conducting a clinical trial for ivermectin.