The first person diagnosed with Ebola on American soil has begun receiving an experimental medication, just as officials announced his condition was worsening. CBS News reported.

Thomas Eric Duncan is now being treated with brincidofovir, receiving an investigational medication in late-stage testing for other types of viruses, officials said Monday.

Brincidofovir is an oral antiviral drug being tested to fight more common viruses, including one that infects patients undergoing bone marrow transplants. Laboratory tests suggested it might also fight Ebola.

Brincidofovir is made by North Carolina-based Chimerix Inc., which said physicians sought federal permission to use the drug. The company did not identify the physicians making the request.

Two other experimental drugs developed specifically for Ebola have been used in American patients. None have been approved by the FDA.