As efforts to discover new COVID-19 medicines roll on, President Donald Trump and others this week focused attention on the decades-old malaria drug chloroquine. Bayer got things rolling with an initial donation of the drug, and now Novartis, Mylan and Teva are taking steps to deliver tens of millions of tablets.

Chloroquine and hydroxychloroquine, a more tolerable formulation, are not approved to treat COVID-19. Still, U.S. authorities and others are exploring their potential following encouraging preliminary results.

In response, Novartis has pledged a global donation of up to 130 million hydroxychloroquine tablets, pending regulatory approvals for COVID-19. Mylan is ramping up production at its West Virginia Facility with enough supplies to make 50 million tablets. Teva is donating 16 million tablets to hospitals around the U.S. On Friday afternoon, Amneal pledged to make 20 million tablets by mid-April.

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At a press conference Thursday, President Trump said the U.S. is planning to make the malaria drug available by prescription “almost immediately.” Because chloroquine isn't FDA-approved to treat COVID-19, the president may have been referencing off-label use.

For his part, FDA chief Stephen Hahn stressed the need to learn more about the potential treatment. It's important to get the “right drug” to the “right patient” at the “right dosage” at the “right time,” the commissioner said. The wrong dose could actually hurt a patient’s condition, he added.

On Friday, NIAID director Anthony Fauci said there's no meaningful evidence to date on chloroquine and COVID-19. Any evidence so far is "anecdotal," he added.

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Meanwhile, the U.S. case count has jumped in recent days. As of Friday, authorities reported more than 14,000 cases in the U.S. California and New York have instituted statewide lockdowns.

The pledges follow Bayer's Thursday donation of 3 million tablets. Together, the commitments represent nearly 220 million chloroquine and hydroxychloroquine tablets for the global COVID-19 response.

Following preliminary reports of the drug’s efficacy, shares for Indian drugmakers Cadila, Torrent and Ipca each jumped, the Economic Times reports. Those companies can also produce the medicine.

While drugmakers aim to boost availability of the med, hydroxychloroquine is already in short supply, according to the American Society of Health-System Pharmacists.

RELATED: Bayer donates millions of tablets of chloroquine to help in COVID-19 fight

Early studies of the medicine in COVID-19 patients have caught the attention of healthcare experts and market watchers. In France, a professor conducted a small study of the malaria drug in 24 patients with novel coronavirus infections. Of those who received the medicine, only 25% tested positive for the virus after six days, according to en24. Meanwhile, of those who didn't receive it, 90% tested positive after that timeframe. The French government now plans to run larger studies.

In a study published last month in Nature, authors wrote that “chloroquine is a cheap and a safe drug that has been used for more than 70 years and, therefore, it is potentially clinically applicable against the 2019-nCoV.”

Aside from efforts to learn more about chloroquine, drugmakers and collaborators are working on new R&D programs and looking to repurpose existing medicines.

Follow these links to read more about drug and vaccine efforts underway.

Editor's note: This story was updated to include Amneal's announcement.