Drugs being repurposed in hopes they will help against COVID-19 cost relatively little to make but may prove challenging to produce in quantities needed for a pandemic, a drug pricing expert has said.

“Any pharmaceutical company manufacturing any treatment currently in clinical trials against coronavirus needs a clear plan to upscale production massively,” said Andrew Hill, a research fellow at the University of Liverpool.

“Otherwise, supplies of these drugs could quickly run out.”

In a study released Friday in the Journal of Virus Eradication, Hill and five other researchers, including Howard University chemist Joseph Fortunak, examined the cost of manufacturing medicines used in recent or ongoing COVID-19 trials.

Using prices for active pharmaceutical ingredients to build estimates, they said Gilead Science’s experimental drug remdesivir, originally made to target Ebola, could be produced for as little as $0.93 (about ¥100) for a day’s supply.

Gilead said the figure did not “accurately reflect” manufacturing costs at scale, but did not give those costs.

Fujifilm Holdings Corp.’s flu drug Avigan runs to $1.45 per day, the researchers said. Fujifilm did not immediately comment.

Meanwhile, decades-old malaria medicine hydroxychloroquine — touted by U.S. President Donald Trump and others as a possible game changer despite no scientific proof it works — costs 8 cents.

Other drugs the researchers examined included the related malaria medicine, chloroquine, the antibiotic azithromycin, Roche’s lung drug Esbriet and rheumatoid arthritis treatment Actemra, as well as an AbbVie HIV drug and a Hepatitis C cocktail.

“Should repurposed drugs demonstrate efficacy against COVID-19, they could be manufactured profitably at very low costs,” the authors wrote, giving range of between $1 and $29 per course of treatment.

Nonetheless, demand for medicines that prove their mettle could swiftly outstrip supply, necessitating new industry alliances, parallel manufacturing by multiple companies and shared intellectual property, Hill said.

“The demands could be huge, and could lead to shortages for people normally taking these drugs for other diseases,” he added.

Roche, which received $25 million in U.S. funding for Actemra’s COVID-19 trial, said it was ramping up output capacity for intravenous Actemra and had boosted supplies by 50 percent in recent weeks. The Swiss drugmaker added that given Actemra was not yet approved for COVID-19, pricing discussions were premature.

For Fujifilm’s Avigan, Japan provided some $128 million to boost supplies to treat 2 million people, as triple the dose is required for COVID-19 than for influenza.

Gilead can produce 140,000 remdesivir treatment courses near-term, and 1 million-plus by December, it has projected.

Sanofi can make millions of hydroxychloroquine doses, but whether that’s enough may depend on whether trials show it should be used for potentially millions of mildly affected patients, or only for severe ICU patients, Chief Executive Paul Hudson said last week.

Sanofi has boosted production of hydroxychloroquine by 50 percent across its eight manufacturing sites worldwide, and said Friday it would donate 100 million doses to 50 countries should trials show the medicine works, while Novartis has pledged 130 million doses and said it was hunting for more ingredients.

So far, some doctors, including in China, say results have been inconclusive.

RELATED PHOTOS Demand for medicines that prove their mettle against COVID-19 could swiftly outstrip supply, necessitating new industry alliances, parallel manufacturing by multiple companies and shared intellectual property. | CDC / VIA REUTERS