Randomised clinical trial: the safety and efficacy of AST-120 in non-constipating irritable bowel syndrome - a double-blind, placebo-controlled study

Aliment Pharmacol Ther 2011; 34: 868–877 Summary Background There is a need for safe and effective treatment options for irritable bowel syndrome (IBS). AST-120 (spherical carbon adsorbent) is a non-absorbed, carbon-based adsorbent with extensive adsorbing capability for histamine, serotonin and other substances implicated in IBS pathogenesis. Aim To evaluate the efficacy and safety of AST-120 in non-constipating forms of IBS. Methods This randomised, double-blind, placebo-controlled trial conducted in the US and Belgium enrolled 115 male and female patients fulfilling Rome III criteria for IBS; individuals with predominantly constipation symptoms were excluded. Subjects were randomised to AST-120 2 g tds or placebo for an 8-week double-blind treatment period, followed by a 2-week single-blind placebo washout and 8-week single-blind active treatment. The primary efficacy endpoint was the proportion of subjects achieving at least a 50% reduction in the number of days with abdominal pain compared with baseline. Results At Week 4, 26.8% of subjects treated with AST-120 responded on the primary endpoint vs. 10.2% in the placebo arm (P = 0.029); at Week 8 response rates were 32.1 and 25.4% respectively (NS). More AST-120 treated subjects experienced improvement in bloating and stool consistency. These benefits abated when AST-120 was replaced by placebo, and resumed once AST-120 was restarted. The frequency of adverse events with AST-120 were less than or equal to placebo. Conclusions AST-120 is safe and well-tolerated and reduces pain and bloating in non-constipating IBS, although beneficial effects may be limited in duration. AST-120 represents a locally acting, non-absorbed, novel treatment for IBS and warrants further studies.