Air Force Master Sgt. Ray Anspach immunizes a soldier against smallpox at Walter Reed Army Medical Center as other medical technicians observe the technique on Jan. 14, 2003. Photo by Michael Dukes/U.S. Army | License Photo

July 16 (UPI) -- The U.S. Food and Drug Administration has approved the first drug to treat smallpox.

The federal agency gave the go ahead Friday to tecovirimat, with the brand name TPOXX, by SIGA Technologies Inc., after trials in animals and humans.


The World Health Organization had declared smallpox, a contagious infectious disease, eradicated in 1980, but the U.S. governments fear smallpox could be used as a bioweapon.

"To address the risk of bioterrorism, Congress has taken steps to enable the development and approval of countermeasures to thwart pathogens that could be employed as weapons," Dr. Scott Gottlieb, FDA commissioner, said in a statement.

He said the approval Friday "provides an important milestone in these efforts. This new treatment affords us an additional option should smallpox ever be used as a bioweapon."

The variola virus, which causes smallpox, was usually spread by direct contact between people.

Ten to 14 days after infection, symptoms included fever, exhaustion, headache and backache. Then a rash of small, pink bumps progressed to pus-filled sores before finally crusting over and scarring. Complications could include encephalitis, eye ulcers and blindness.

Studies were conducted in rabbits and non-human primates infected with viruses closely related to the virus that causes smallpox with the use of the drug and a placebo.

Then, TPOXX's was evaluated in 359 healthy human volunteers without a smallpox infection. The most frequently reported side effects: headache, nausea and abdominal pain.

Results of the trial were published in the July 5 issue of the New England Journal of Medicine.

The application was approved through Fast Track and Priority Review designations. TPOXX also received Orphan Drug designation, an incentive to assist and encourage the development of drugs for rare diseases and a Material Threat Medical Countermeasure Priority Review Voucher. The latter are "intended to treat or prevent harm from specific chemical, biological, radiological and nuclear threats," the FDA said.

TPOXX will be available initially only through the U.S. government's Strategic National Stockpile.

SIGA Technologies, whose lead product is TPOXX, is "a company that specializing in the development and commercialization of solutions for serious unmet medical needs and biothreats," according to its website.

"TPOXX is proof that public-private partnerships work when the partners are committed to a focused mission," Dr. Phil Gomez, chief executive officer of SIGA Technologies, Inc., said in a company press release. "The FDA approval of TPOXX achieves an important objective for both SIGA and our lead partner in the U.S. Government, the Biomedical Advanced Research and Development Authority. The approval validates this novel smallpox therapy as an important medical countermeasure in response to a potential smallpox outbreak."