Stage 1 will consist of a blinded parallel group safety study of 4 cohorts in which 24 subjects will be randomized (1:1:1:1) into four equally sized groups to receive one of three doses of EC-18 (500 mg, 1000 mg, 2000 mg; unit dose of 500 mg) or placebo. Stage 2 of the study will evaluate both safety and efficacy.