The US Food and Drug Administration (FDA) on July 14 approved the first drug with an indication for treatment of smallpox.

Smallpox, a contagious and sometimes fatal infectious disease, was declared eradicated in 1980, by the World Health Organization. However, there have been longstanding concerns that smallpox could be used as a bioweapon. TPOXX (tecovirimat) is a small-molecule antiviral treatment for smallpox, the first therapy specifically approved for this indication.

"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. Today's approval provides an important milestone in these efforts. This new treatment affords us an additional option should smallpox ever be used as a bioweapon," Scott Gottlieb, FDA Commissioner, said in a statement.

The approval "reflects the FDA's commitment to ensuring that the US is prepared for any public health emergency with timely, safe and effective medical products", he added. TPOXX's effectiveness against smallpox was established by studies conducted in animals infected with viruses that are closely related to the virus that causes smallpox.

More animals treated with TPOXX lived compared to the animals treated with placebo. Further, TPOXX's safety was also evaluated in 359 healthy human volunteers without a smallpox infection. The most frequently reported side effects were headache, nausea and abdominal pain.

TPOXX also received Orphan Drug designation, which provides incentives to assist and encourage the development of drugs for rare diseases and a Material Threat Medical Countermeasure Priority Review Voucher, which provides additional incentives for certain medical products intended to treat or prevent harm from specific chemical, biological, radiological and nuclear threats, the statement said. The FDA granted approval of TPOXX to New York-based pharmaceutical company SIGA Technologies Inc and will be available initially only through the US government's Strategic National Stockpile (SNS).