After a patient is randomized and enters the Treatment Period, he/she will take the appropriate study medication once a day for 84 days and return to the clinic at two week intervals for a total of six visits during the Treatment Period. During the Treatment Period, patients will maintain a daily diary and complete questionnaires. One week after completing the 84-day Treatment Period, patients return to the clinic for final safety evaluations which include a physical examination, electrocardiogram, and clinical laboratory testing.