Population: This study will determine the safety, tolerability and pharmacokinetics of a single iv dose of ETI-204 in subjects 18 to 50 years of age. Three cohorts will be studied sequentially: subjects receiving 120 mg, 240 mg and 360 mg of ETI-204. The study will be randomized, double-blind, and stratified by gender. Each cohort will contain 15 subjects (including at least four females), twelve who will receive ETI-204 and three who will receive placebo.