NIH finds potential coronavirus oral antiviral drug

The National Institutes of Health (NIH) on Thursday announced a potential oral antiviral treatment to lessen the severity of COVID-19 disease, ahead of clinical studies assessing efficacy in patients.

Researchers said the experimental drug, TEMPOL, showed promise in cell cultures by impacting the virus’ ability to replicate, or impairing an enzyme called RNA replicase. Findings were published in the journal Science.

"We urgently need additional effective, accessible treatments for COVID-19," Dr. Diana W. Bianchi, National Institute of Child Health and Human Development (NICHD) director, said in a statement posted Thursday. "An oral drug that prevents SARS-CoV-2 from replicating would be an important tool for reducing the severity of the disease."

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A team of researchers with Dr. Tracey A. Rouault, head of the NICHD arm on Human Iron Metabolism, uncovered the drug's potential by analyzing how the virus replicates in cells. The enzyme under study, RNA replicase, functions best with two so-called iron-sulfur clusters, whereas previous studies incorrectly pinned the structures as zinc-binding sites, according to the NIH. 

The feature of the enzyme allowed the team to take advantage of a weakness in the virus; the drug degrades the iron-sulfur clusters, thereby inhibiting viral replication, and could potentially apply to other diseases with similar binding sites.

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Experiments and earlier animal studies assessing the drug with other diseases helped researchers at hand establish a dosage to use in lungs and salivary glands, said to be major targets of the virus.

"Given TEMPOL’s safety profile and the dosage considered therapeutic in our study, we are hopeful," Rouault added. "However, clinical studies are needed to determine if the drug is effective in patients, particularly early in the disease course when the virus begins to replicate."

Researchers intend to run further animal studies and aim to conduct a clinical trial to assess the drug against COVID-19.