Durham-based Chimerix (Nasdaq: CMRX)  is providing its experimental antiviral drug to a Dallas patient being treated for Ebola, an emergency step authorized by the Food and Drug Administration.

Officials at Texas Health Presbyterian Hospital said Monday that their patient, Thomas Eric Duncan, is in critical condition and being treated with Brincidofovir, an oral medicine developed by Chimerix Inc.

Chimerix said earlier that physicians sought FDA permission to use the company’s drug, which is in late-stage testing for several other types of viruses.

The FDA grants emergency access to unapproved drugs on a case-by-case basis, usually when a patient faces a life-threatening condition for which there are no alternatives. The agency has not approved any drugs or vaccines to safely and effectively treat Ebola.

Duncan was diagnosed with Ebola in Dallas last Tuesday after recently arriving from Liberia.

Brincidofovir is an antiviral drug being tested against several common viruses, including one that infects patients undergoing bone marrow transplants. Chimerix is working with the U.S. Department of Defense on developing the drug as a treatment against smallpox. Laboratory tests suggested it may also work against Ebola.

The company said in a statement it is working with the FDA to finalize plans for an Ebola study of Brincidofovir, its lead drug candidate. The company has no other products on the market or in testing.

Shares of Chimerix Inc. jumped $1.43, or nearly 5 percent, to $31.49 Monday.

“Two other experimental drugs developed specifically for Ebola have been used in American patients, though it’s unclear if they had any effect. The small supply of one drug, ZMapp, was exhausted after being used on a few patients — though government officials say more should be available in the next two months. A second drug, TKM-Ebola from Tekmira Pharmaceuticals, has been used in at least one patient and is said to be in limited supply.

The Centers for Disease Control and Prevention has consulted with U.S. hospitals about more than 100 potentially suspicious cases in recent months. More than a dozen were worrisome enough to merit Ebola blood tests. Only the Dallas patient had Ebola.

Federal officials say they are confident they can stay on top of any more cases that arrive.

In its announcement Monday, Chimerix said the drug, which is delivered orally, is being provided for potential use against the Ebola outbreak at the request of treating physicians.

“When the current Ebola outbreak was reported in early spring, Chimerix sent Brincidofovir and some other compounds to be tested against the Ebola virus. Like the smallpox virus, the Ebola virus has to be tested in special laboratories at institutions such as the US Centers for Disease Control (CDC) and laboratories affiliated with the National Institutes of Health (NIH),” the company explains at its website. “The test-tube data showing the potent activity of brincidofovir was reported back to the scientists at Chimerix in late August. The results currently available are from experiments performed in test tubes, not in humans or animals. To date no other data are available, but Chimerix is continuing to work with the CDC and NIH to explore activity in animal models.”

The FDA has granted Emergency Investigational New Drug Applications in order to speed up development and testing.

“Chimerix is committed to working with global health organizations and government agencies in the fight against the Ebola virus outbreak,” said M. Michelle Berrey,  an MD, who is Chief Executive Officer of Chimerix. “Based on in vitro data from work conducted by the CDC and the National Institutes of Health suggesting brincidofovir’s activity against Ebola, we are hopeful that brincidofovir may offer a potential treatment for Ebola Virus Disease during this outbreak.”

Brincidofovir already is in Phase 3 clinical trials for use against other viruses. According to the company, ” It works by keeping viruses from creating additional copies of themselves.”

The company said it is working with the FDA to set up a clinical trial protocol for testing of the treatment in patients who are confirmed to have the Ebola virus. The tests are to determine safety, tolerability and efficacy.

Test-tube results showed “activity” against Ebola, the company said. In-animal tests are already underway.

Research firm ups Chimerix expectations

Last week, Wall Street research firm Piper Jaffray raised its price target on Chimerix shares and maintained a buy (“overweight”) rating on the stock.

Analyst Joshua Schimmer called Brincidofovir an “attractive option” as a “potential treatment for Ebola but also for smallpox.”

Last month, Chimerix received $17 million from the Biomedical Advanced Research and Development Authority (BARDA) for a continuation of research into Brincidofovir as a treatment for smallpox.BARDA awarded Cimerix an initial contract worth nearly $25 million in 2011, and the company could receive more than $80 million overall.

“A drug needs to show activity in two animal species, human safety to qualify for stockpiling; CMRX may be able to satisfy safety requirement with CMV program,” the research firm said.

Another Triangle-based firm, BioCryst (Nasdaq: BCRX), is developing a potential Ebola treatment.

Drug giant GlaxoSmithKline (NYSE: GSK) also is testing a potential vaccine. Its North American headquarters are located in RTP.

Drug used to treat ailing boy

The same drug from Chimerix was used to treat seven-year-old Josh Hardy earlier this year after receiving FDA approval in March. He contracted a virus while undergoing cancer treatment.

The FDA allowed “compassionate use” after a media campaign that included family appeals on Facebook and a CNN interview.

Josh was treated at St. Jude Children’s Research Hospital in Memphis, Tenn.

Brincidofovir has “the potential to become the first broad-spectrum antiviral for the prevention and treatment of clinically significant infections and diseases caused by DNA viruses,” the company said.

Josh was the first patient in a pilot trial of the medicine.

The FDA allows someone with an immediate life-threatening illness to ask for permission to use experimental drugs that have not yet received the agency’s approval.