Comparison of two different formulations of mebeverine hydrochloride in irritable bowel syndrome

A total of 213 patients were recruited to a multicentre, randomised, double-blind, double dummy, general practice study lasting eight weeks. The objectives of the study were (i) to demonstrate therapeutic equivalence of mebeverine hydrochloride 200 mg b.i.d. capsules (Colofac MR) and 135 mg t.i.d. tablets (Colofac) in the treatment of abdominal pain in irritable bowel syndrome (IBS) and (ii) to evaluate safety and physicians' and patients' assessments of therapeutic response. Patients were randomised at day 0 and assessments performed after four and eight weeks. Primary and secondary efficacy endpoints were number of responders (response being defined as 50% or more improvement in global mean visual analogue scale for abdominal pain); patients' and physicians' global assessment of therapeutic response; and physicians' global impression of patient symptoms. Safety was assessed from adverse event reports and routine laboratory tests. Therapeutic equivalence was proven statistically (difference < 18%; p = 0.003), with 65/92 (71%) of the 135 mg t.i.d. group and 64/92 (70%) of the 200 mg b.i.d. group classified as responders. The patients' evaluation of response (week 8) was that 75% of 135 mg t.i.d. and 81% of 200 mg b.i.d. improved; the physicians' assessment of therapeutic response (week 8) was that 64% of 135 mg t.i.d. and 70% of 200 mg b.i.d. had no or mild symptoms. In conclusion, Mebeverine hydrochloride 200 mg b.i.d. (Colofac MR) was shown to be therapeutically equivalent to mebeverine hydrochloride 135 mg t.i.d. (Colofac) in the treatment of abdominal pain in IBS. Results for the secondary efficacy variables were comparable. No safety concerns were identified.