Biotechnology company Gilead Sciences is halting emergency access to its experimental coronavirus drug, citing "overwhelming demand."

The coronavirus outbreak has caused such a surge in requests for the drug, called remdesivir, that they have "flooded an emergency treatment access system that was set up for very limited access to investigational medicines," the company said in a statement on its website.

Under exceptional circumstances, the Food and Drug Administration allows companies to provide not-yet-approved drugs to people outside of clinical trials in what are known as "compassionate use" requests.

The system was never designed to be used as a response to a pandemic, the company said. To stem demand, Gilead will pivot from accepting compassionate-use requests to only providing treatment through expanded access programs.

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Remdesivir is an antiviral drug that was originally tested in humans with the Ebola virus. It also has shown promise as a treatment for severe acute respiratory syndrome, or SARS, and Middle East respiratory syndrome, known as MERS.

The University of Nebraska Medical Center, in conjunction by the National Institute of Allery and Infectious Diseases, is conducting the first clinical trial of remdesivir in the U.S. as a potential treatment for COVID-19, the potentially lethal illness caused by the coronavirus.

Gilead said it will process previously approved compassionate-use requests for remdesivir, but it is no longer accepting new ones. Gilead will make exceptions for pregnant women and for children under age 18 with severe cases of COVID-19.

"We recognize that there are severely ill patients who are unable to enroll in clinical trials and for whom no approved treatment options are effective," the company said. "Gilead has been working with regulatory agencies to provide remdesivir to these patients where feasible. To date, we have provided emergency access to remdesivir for several hundred patients in the United States, Europe and Japan."

There are currently no drugs approved to treat the coronavirus.