Oral spherical adsorptive carbon for the treatment of intractable anal fistulas in Crohn's disease: a multicenter, randomized, double-blind, placebo-controlled trial.

Objectives: Anal fistulas are common in individuals with Crohn's disease (CD). We sought to evaluate the efficacy of oral spherical adsorptive carbon (AST-120) (Kremezin; Kureha Corporation, Tokyo, Japan) for the treatment of intractable anal fistulas in patients with CD.
Methods: In this multicenter, randomized, double-blind, placebo-controlled trial, patients with CD and at least one active anal fistula under treatment were assigned to receive either AST-120 or placebo for 8 wk. Improvement was defined as a reduction of 50% or more from baseline in the number of draining fistulas observed at both 4 and 8 wk. Remission was defined by closure of all draining fistulas at both 4 and 8 wk. The Perianal Disease Activity Index (PDAI) and Crohn's Disease Activity Index (CDAI) were also assessed.
Results: In total, 62 patients were randomized, of whom 57 received AST-120 (N = 27) or placebo (N = 30). The improvement rate in the AST-120 group (37.0%) was significantly greater than that in the placebo group (10.0%) (P= 0.025). The corresponding remission rates were 29.6% and 6.7%, respectively (P= 0.035). PDAI significantly improved at both 4 and 8 wk with AST-120, compared to placebo (P= 0.004 and P= 0.005, respectively). CDAI was also significantly improved at both 4 and 8 wk in the AST-120 group, compared to the placebo group (P= 0.007 and P= 0.001, respectively). AST-120 treatment was well tolerated and no life-threatening adverse events were observed.
Conclusion: AST-120 is useful for the control of intractable anal fistulas in CD patients.