Patients must complete at least 12 days of all baseline diary entries within the 14 day screening period to be eligible to participate in the study. Patients completing fewer than 12 days of diary entries may, at the investigator's discretion, repeat the screening period diary. As long as the patent can complete and enter the study within 6 weeks, baseline laboratory studies need not be repeated. If repeating the 2 weeks' baseline diary will result in a period longer than 6 weeks from consent to start of treatment, the medical monitor must be consulted prior to randomization.