A randomised, controlled comparison of low-dose polyethylene glycol 3350 plus electrolytes with ispaghula husk in the treatment of adults with chronic functional constipation

Objective: To compare the efficacy and safety of polyethylene glycol (PEG) 3350 plus electrolytes (PEG+E; Movicol((R))) with that of ispaghula husk (psyllium; Konsyl((R))) in the treatment of constipation. Patients: Male or female adults with chronic functional constipation. Methods: This was a randomised, controlled, open-label, parallel-group trial. Study treatment was either PEG+E 13.8g/sachet dissolved in water twice daily or ispaghula husk 3.5g/sachet dissolved in water twice daily for a period of 2 weeks. Assessments were at baseline and after 1 and 2 weeks' therapy and by patient daily diary card. The primary outcome measures were weekly defaecation rate, stool consistency according to the Bristol Stool Form scale, time to first defaecation, and overall efficacy, which combined defaecation rate, stool consistency and difficulty on defaecation. Adverse effects were recorded and laboratory assessments were performed before and at the end of the treatment period. Results: Sixty-three patients were randomised to each treatment group. Treatment was highly effective in 50/63 patients in the PEG+E group compared with 26/63 in the ispaghula husk group, and the overall efficacy rates were 92% and 73%, respectively (p = 0.005). PEG+E increased the mean weekly defaecation rate from 1. 18 (SD 0.77) at baseline to 7.95 (SD 3.49) after 1 week and 8.48 (SD 3.55) after 2 weeks. In the ispaghula husk group the mean weekly defaecation rate increased from 1.33 (SD 0.68) at baseline to 5.33 (SD 2.81) after 1 week and to 5.71 (SD 2.49) after 2 weeks. The treatment differences for defaecation rates were all statistically significant (p < 0.001). Two weeks of treatment with PEG+E or ispaghula husk normalised stools in 55/63 (87.3%) and 42/63 (66.7%) of patients (p < 0.001). The incidence of adverse effects did not differ between groups and none were serious or required any treatment. Laboratory evaluations found no adverse effect from either treatment. Conclusion: The present study demonstrated that low-dose PEG 3350 plus electrolytes is more effective and more rapid in its onset of action than ispaghula husk, and is equally well tolerated.