Safety, Tolerability, Pharmacokinetics (PK) of the Anti-Orthopox Drug, ST-246

Inclusion Criteria: 1. 18 - 75 yrs 2. Healthy volunteer 3. Ability to consent 4. Available for clinical follow-up for study 5. Not taking other medications 6. Adequate venous access 7. Using adequate birth control; negative pregnancy test 8. Able and willing to avoid alcohol for screening and study duration Exclusion Criteria: 1. Inability to swallow study medication 2. Pregnant or breast-feeding 3. Medical condition, e.g., asthma, hypertension, angioedema, traumatic brain injury other than concussion, bleeding disorder, blood dyscrasia, idiopathic seizures, cardiac disease that limits activity, diabetes, active malignancy, Hepatitis B or C, HIV or AIDS, chronic microbial infection, 4. History of drug allergy that contraindicates study participation 5. Medical, psychiatric, social, occupational or other reason that jeopardizes the safety/rights of participant or renders he/she unable to comply with the protocol (including drug or alcohol abuse, or homelessness) 6. Clinically abnormal ECG 7. Has or will participate in a clinical trial or experimental treatment within 30 days of, or during, the study 8. Cannot or will not do physical exercise 24 hrs before and after PK days 9. Will not consume grapefruit/grapefruit juice during study 10. Vaccination within 2 wks of screening, or planned before Day 42 of study 11. Treatment with prednisone or equivalent immunosuppressant/modulatory drug \<3 mths before screening 12. Clinically significant physical exam and lab results \<2weeks from 1st study drug dose