A randomised double-blind placebo-controlled trial of lidamidine HCL in irritable bowel syndrome

We have previously shown electro-mechanical recto-anal alterations in irritable bowel syndrome patients (Awad R. Neurogastroenterol Motil 1993; 5; 265-271). To assess whether the alpha 2-agonist lidamidine HCL is able to modify these physiological alterations and alleviate clinical symptoms, 50 patients with irritable bowel syndrome were studied in a random, double blind, placebo-controlled trial.

Lidamidine HCL (4 mg) or placebo was taken orally t.i.d. with food. Fasting and post-prandial electrical and mechanical activities of rectum and internal anal sphincter were recorded before and at the end of treatment. Recto-anal sensitivity was also tested.

After treatment, post-prandial duration of spontaneous recto-anal inhibitory reflex diminished in the lidamidine group (18.9 +/- 1 vs. 15.1 +/- 1.3 sec; p < 0.05). Amplitude of induced rectoanal inhibitory reflex decreased after lidamidine (24.6 +/- 2.9 vs 17.3 +/- 3 mmHg; p = 0.02). Rectal electrical activity showed no changes during basal and post-prandial periods in any group. Rectal painful sensation decreased after treatment with lidamidine (54.8 +/- 5.4 vs 43.6 +/- 3.5 ml; p < 0.05) as well as with placebo (p < 0.05). Abdominal distension and frequency, severity and duration of pain diminished in both groups (p < 0.05).

Lidamidine decreased the augmented mechanical response to food, reduced rectal sensitivity, and relieved symptoms. These facts suggest that in spite of the strong placebo response obtained, lidamidine HCL can become a useful alternative for treatment of patients with irritable bowel syndrome.