 After a baseline period of 1 one week, subjects who had met the inclusion criteria were entered into the treatment phase of the study. Patients were randomised to receive either Movicol or matching Placebo for two 2 weeks. Following the treatment phase, patients underwent a two 2-week placebo washout period prior to crossing over to receive the alternative treatment e.g. those patients who took Movicol were given the matching Placebo or vice versa on completion of the washout period for two 2 weeks. 