Effect of oral tacrolimus (FK 506) on steroid-refractory moderate/severe ulcerative colitis

Background: Steroid refractory ulcerative colitis is most commonly treated with intravenous ciclosporin to avoid colectomy. In search for an alternative drug that can be administered orally we investigated oral tacrolimus (FK 506) for this indication. Methods: Nine patients with active, moderate/severe steroid refractory UC were treated with oral tacrolimus with a daily dose of 0.15 mg/kg body weight. After patients had responded azathioprine was added for long-term immunosuppression. Results: All patients responded within 1-2 weeks. After 12 weeks of tacrolimus therapy six patients (67%) were in complete remission, two patients (22%) had mild to moderate disease activity, and one patient (11%) underwent colectomy. After a mean follow up of 21 months six of the nine patients (67%) had their colon in situ. Two patients developed severe side-effects, one thrombopenia with intestinal bleeding, and one bicytopenia. Mild side-effects were common. Conclusion: Oral tacrolimus may be an effective alternative to intravenous ciclosporin for the therapy of steroid-refractory ulcerative colitis. Patients receiving tacrolimus need to be watched carefully for side-effects.