Patients were randomized 1:1:1 to a single loading infusion of AZD9773 250 U/kg followed by 50 U/kg every 12 hours ( low dose , n = 100 ) , a single loading infusion of AZD9773 500 U/kg followed by 100 U/kg every 12 hours ( high dose , n = 100 ) , or placebo ( n = 100 ) for 5 days .