Comparison of a low dose polyethylene glycol electrolyte solutionwith lactulose for treatment of chronic constipation

Background—Polyethylene glycol(PEG) 3350 is a non-absorbable, non-metabolised osmotic agent used inlavage solutions for gut cleansing.
Aims—To compare the efficacy of PEGand lactulose in chronic constipation.
Methods—A total of 115 patientswith chronic constipation entered a multicentre, randomised,comparative trial. They initially received two sachets containingeither PEG (13 g/sachet) or lactulose (10 g/sachet) and were given anoption to change the dose to one or three sachets/day, depending on response.
Results—Ninety nine patientscompleted the trial. After four weeks, patients in the PEG group (n=50)had a higher number of stools and a lower median daily score forstraining at stool than patients in the lactulose group (n=49). Overall improvement was greater in the PEG group. Clinical tolerance was similar in the two groups, but flatus was less frequently reported inthe PEG group. The mean number of liquid stools was higher in the PEGgroup but the difference was significant only for the first two weeks.There were no serious adverse events and no significant change inlaboratory tests in either group. At the end of the study, the numberof sachets used by the patients was 1.6 (0.7)/day in the PEG group and2.1 (0.7)/day in the lactulose group. Sixty one patients completed afurther two months open study of one to three sachets PEG daily; therewas no loss of efficacy and no serious toxicity.
Conclusion—Low dose PEG 3350 wasmore effective than lactulose and better tolerated.

Keywords:constipation; polyethylene glycol; lactulose; cathartics; randomised trial