New Single-Dose Orthopoxvirus Drug In First Stage Of Human Trials

Prior to eradication, variola virus, the causative agent of smallpox and member of the orthopoxvirus family, was estimated to have killed, crippled, or disfigured up to 10% of the human population. Highly communicable with an exceptionally high morbidity rate, smallpox currently poses a threat as an instrument of biowarfare placing it at the forefront of focus for effective preventative and treatment therapies.

In this phase I study fasting healthy volunteers were administered single oral doses of 500, 1,000, and 2,000 mg of the drug ST-246 and non-fasting healthy volunteers received 1,000 mg. No adverse reactions were observed and no subjects were withdrawn from the study, overall ST-246 was found to be generally well tolerated.

Upon further testing, researchers found absorption to be greater in nonfasting volunteers at a rate of approximately 2 to 3 hours and exposure levels to be sufficient for inhibiting orthopoxvirus replication.

"In conclusion, ST-246 is safe and well tolerated when administered orally as a single dose to healthy human volunteers in a fasting state or non-fasting state," say the researchers.