Lubiprostone

Lubiprostone (Amitiza (TM)) is an oral bicyclic fatty acid that selectively activates type 2 chloride channels in the apical membrane of the gastrointestinal epithelium, resulting in increased fluid secretion. A In two pivotal, randomised, double-blind, multicentre phase III studies in patients with chronic idiopathic constipation, the frequency of spontaneous bowel movements (SBMs) was significantly greater in patients receiving lubiprostone 24 mu g twice daily than in those receiving placebo at each weekly timepoint throughout both 4-week studies (p < 0.05). At week I in one pivotal trial, the mean frequency of SBMs in the lubiprostone group was 5.9 per week compared with 4.0 per week in the placebo group (p < 0.0001) [baseline SBMs 1.3 and 1.5 per week]. Significantly greater improvements occurred with lubiprostone than placebo in the degree of straining, stool consistency and constipation severity (where reported) in both pivotal studies (p < 0.05 for all comparisons at all timepoints). Lubiprostone was generally well tolerated in clinical trials with no reports of treatment-related serious adverse events in pivotal trials. Nausea was the most common adverse event, occurring in up to 31% of patients receiving lubiprostone.