Tacrolimus (FK506) Study in Moderate to Severe Refractory Ulcerative Colitis Patients

Inclusion Criteria: * Moderate to severe refractory UC patients * Disease activity: more than 4 times of stool a day, bloody stool, moderate to severe endoscopic finding * Steroid resistance or dependence to meet at least one of the following condition:no efficacy with more than 40mg/day or 1mg/kg/day of steroid over at least 1 week, no efficacy with 30-40mg/day of steroid over at least 2 weeks,exacerbation along with steroid reduction Exclusion Criteria: * Mild or fulminant type * Renal failure patients, hepatic failure patients * Patients taking 6-mercaptopurine, cyclosporin or other immunosuppressants within 12 weeks prior to entry * Patients who received LCAP or GCAP within 2 weeks prior to entry * Patients who changed the dose of steroid or started steroid within 2 weeks prior to entry. * Patients who changed the dose of steroid or started steroid within 1 week prior to entry in case they received more than 40 mg/ day or 1mg/kg/day of steroid just before the study.