Tpoxx Approved to Treat Smallpox
July 13, 2018 – The U.S. FDA has approved Tpoxx® (tecovirimat), manufactured by SIGA Technologies, Inc., to treat smallpox. It is the first drug to receive FDA approval for the indication.
Naturally occurring smallpox, an infectious disease caused by the Variola major and Variola minor viruses, was eradicated worldwide in 1980. It spreads via direct contact with infected individuals, with symptoms manifesting in 10 to 14 days. These symptoms can include nausea, fever, headaches, back pain, and fatigue, as well as a characteristic rash that progresses to sores that eventually crust over and scar. The disease can lead to complications such as encephalitis (inflammation of the brain), corneal ulcers (an open sore on the eye’s cornea), and blindness.
A global immunization campaign helped to bring smallpox under control, leading to its current status as an eradicated disease. However, concerns have remained regarding its potential for use in biological terrorism. Samples of smallpox virus still exist in carefully controlled laboratory settings for the sake of scientific research. The FDA granted Tpoxx a Material Threat Medical Countermeasure priority review, the first of its kind.
Because naturally-occurring smallpox has been eradicated, Tpoxx could not be studied in human patients infected with the virus. Human trials involved healthy volunteers not infected by smallpox, and assessed product safety and side effects only. Product efficacy was determined based on animal studies that used viruses closely related to smallpox, rather than the smallpox virus itself. Survival rates ranged from 80% to 100% in animals treated with Tpoxx, though study results indicated that Tpoxx may be less effective in immune-compromised individuals.
Recommended dosing with Tpoxx is three 200mg capsules (totally 600mg) twice daily for adults. Children who receive Tpoxx should be at least 13kg (29 lbs); dosage for pediatric patients is based on weight. Patients should eat a meal with moderate to high fat content no more than half an hour before taking Tpoxx, and continue treatment for 14 days. In patients with compromised immune systems, the drug may be less effective.
SIGA Technologies developed Tpoxx in association with U.S. Department of Health and Human Services’ Biomedical Advanced Research and Development Authority (BARDA).
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