Eery week for 3 weeks after randomization, doses were titrated to an optimal or maximum dose of 2 mg/24 hours, 4 mg/24 hours, or 6 mg/24 hours.

• 在随机分组后的三个星期里，每周剂量设计成最佳或最大，采取2mg/24hours,4mg/24hours,或6mg/24hours。