A randomized, multicenter comparison of polyethylene glycol laxative and tegaserod in treatment of patients with chronic constipation

Polyethylene glycol (PEG) 3350 (MiraLax) and tegaserod (Zelnorm), a serotonin subtype 4 receptor partial agonist, are currently approved for treatment of constipation. This study was designed to compare the efficacy of each product over a 4-wk treatment period.

Study patients who met defined criteria for chronic constipation were randomized in this open-labeled, parallel, multicenter study to receive the PEG laxative as a single daily dose of 17 g or tegaserod tablets 6 mg b.i.d., for 28 days. As a primary end point, treatment success was defined for each patient as relief of modified ROME criteria for constipation for 50% or more of their treatment weeks. Various secondary measures were also assessed. An interactive voice response system (IVRS) recorded patient reported daily bowel movement experience and study efficacy and safety information.

A total of 237 patients were enrolled and received treatment at one of 25 centers. Successful treatment according to the primary end point was seen in 50.0% of the PEG and 30.8% of tegaserod patients (P= 0.003). By treatment weeks 3 and 4, significantly more PEG patients were successfully treated according to primary and secondary response definitions. PEG patients experienced more bowel movements per week (P= 0.019) and had significantly greater improvement in constipation symptoms (P= 0.016) based on results from a validated patient self-reported questionnaire. Tegaserod patients experienced a significantly higher incidence of headaches. Otherwise, there were no significant differences in adverse events.

While PEG laxative and tegaserod are safe for their intended use in chronic constipation, PEG had superior efficacy, caused fewer headaches, and produced greater improvement of constipation symptoms.