Safety, Tolerability and Pharmacokinetic Study of Multiple Doses of CS-8958

The purpose of this study is to test the safety and tolerability of an investigational multi-dose inhaled flu medication, CS-8958. Study participants will include 16 males and females, aged 18-55 years of age, inclusive. Participants will be divided into two treatment groups (Groups A and B) with each group consisting of 8 subjects. Participants will be involved in study related procedures for a maximum of 14 weeks from initial screen to the follow up visit. 6 subjects in Group A will be administered 40 mg of CS-8958 drug and two subjects will receive placebo (substance containing no medication), once a week for six weeks. In Group B six subjects will be administered 40 mg of CS-8958 drug and two subjects will receive placebo, twice a week for six weeks. Study procedures will include blood and urine samples, ECGs (measure of heart activity), blood pressure, pulse rate and functional oxygen saturation of arterial hemoglobin. Also continuous cardiac telemetry will be performed as well as physical examinations and spirometry assessments.