Photo/Illutration The experimental oral antiviral drug molnupiravir is in the final stage of clinical testing. (Provided by Merck & Co.)

Oral antiviral drugs under development for COVID-19 patients with mild symptoms are being eyed as potential game changers in the fight against the novel coronavirus.

Currently, only intravenous drips are certified by the Japanese government for patients with mild symptoms. But oral medicines could be taken at home and are easy to prescribe and use.

Experts point to potential challenges in using them effectively, but drug companies are racing to produce therapeutic medications and governments appear optimistic they might help in turning the tide in the ongoing health crisis.

Health minister Norihisa Tamura said at a Sept. 3 news conference that the government wants drug makers to quickly apply for approval for their oral medicines so they can be provided to the public as soon as possible.

Foreign companies are ahead of Japan at developing oral medicines to combat COVID-19.

The U.S. drugmaker Merck & Co. is conducting the final stage of clinical testing for Molnupiravir.

It is expected to compile the test results as early as October and apply for emergency use authorization (EUA) in the United States by the end of the year.

Pfizer Inc.’s clinical testing has also reached its final stage of trials, so it too aims to make an EUA application within the year.

Along with those applications, the companies may also apply to the Japanese health ministry for approval here.

Swiss pharmaceutical company F. Hoffmann-La Roche Ltd. is also in the final stage of clinical testing for an oral drug and is expected to file for approval as early as 2022.

In Japan, drug maker Shionogi & Co. announced at a news conference in Tokyo on Sept. 29 that it has started its final clinical testing.

The company plans to conduct clinical trials with about 2,000 patients in Japan who are either asymptomatic or have mild symptoms. It aims to apply for health ministry approval as early as this year.

Shionogi said that it assumes that patients will take its oral drug once a day for five days.

Those oral medicines can prevent a novel coronavirus that has infected cells from reproducing. The drug will block the enzyme activity necessary for the virus to multiply.

Reiko Saito, professor of public health at Niigata University, notes it will be necessary to establish a testing system that can determine, cheaply and swiftly, whether patients have contracted COVID-19 and then provide them with oral drugs.

“Oral medicines are necessary, but they are drugs to prevent the virus from reproducing further by using them at an early stage,” she said. “If there are no systems that allow patients to take oral medications as soon as they test positive, the drugs will not be fully effective.”

In the case of influenza, if patients believed to have the virus go to see doctors at hospitals, they are diagnosed right away with simple antigen test kits and are then given oral medicines. This kind of system already exists for treating influenza and it has reduced the number of influenza patients with serious symptoms.

(This article was written by Kai Ichino and Kanako Tanaka.)

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