Duration of Treatment: The duration of Part I was 26 weeks: 8 weeks of placebo run-in, 2 weeks of dose titration, 12 weeks of maintenance, and 4 weeks of tapering-off period. The duration of Part II was 1 year. The duration of Part III was planned to be 1 year (some patients were treated for >1 year). The duration of Part IV was >3 years (patients could continue treatment with ESL until market availability).