A Phase I, Subject and Investigator Blind Randomized, Study to Investigate the Pharmacokinetics, Safety and Tolerability of Retosiban in Healthy Japanese Women

This study in healthy, adult Japanese women will characterize the PK, safety and tolerability of retosiban at the therapeutic doses planned to be evaluated in Phase 3. The PK data will be compared to a sub-set of Caucasian women given the same dose of retosiban. This study has two cohorts, cohort 1 will be a double-blind sponsor-open (subjects and investigator blinded and sponsor unblinded), randomized, continuous 48 hours (h) infusion study in healthy, adult Japanese women of child-bearing potential. Cohort 2 is an open label and continuous retosiban 48 h infusion study in Caucasian, adult, healthy women of child bearing potential. So, the PK can be compared with those of Japanese women. Approximately 32 subjects will be enrolled. In cohort 1, approximately 24 subjects will be enrolled and randomized to retosiban and placebo (2:1 ratio) to have 18 women with 12 active, 6 placebo completed subjects. In Cohort 2, 8 subjects will be enrolled to have 6 competed subjects. The total duration of a subject's involvement in this part is anticipated to be up to 6 weeks (including the 28 day screening period).