Randomized Clinical Trial: Macrogol/PEG 3350 Plus Electrolytes for Treatment of Patients With Constipation Associated With Irritable Bowel Syndrome

OBJECTIVES: Polyethylene glycol (PEG) 3350 plus electrolytes (PEG 3350 + E) is an established treatment for constipation and has been proposed as a treatment option for constipation associated with irritable bowel syndrome (IBS-C). This study aimed to compare the efficacy and safety of PEG 3350 + E vs. placebo in adult patients with IBS-C. METHODS: Following a 14-day run-in period without study medication, patients with confirmed IBS-C were randomized to receive PEG 3350 + E (N = 68) or placebo (N = 71) for 28 days. The primary endpoint was the mean number of spontaneous bowel movements (SBMs) per day in the last treatment week. RESULTS: In both groups, mean weekly number of SBMs (+/- s.d.) increased from run-in. The difference between the groups in week 4 (PEG 3350 + E, 4.40 +/- 2.581; placebo, 3.11 +/- 1.937) was statistically significant (95% confidence interval: 1.17, 1.95; P < 0.0001). Although mean severity score for abdominal discomfort/pain was significantly reduced compared with run-in with PEG 3350 + E, there was no difference vs. placebo. Spontaneous complete bowel movements, responder rates, stool consistency, and severity of straining also showed superior improvement in the PEG 3350 + E group over placebo in week 4. The most common drug related treatment-emergent adverse events were abdominal pain (PEG 3350 + E, 4.5%; placebo, 0%) and diarrhoea (PEG 3350 + E, 4.5%; placebo, 4.3%). CONCLUSIONS: In IBS-C, PEG 3350 + E was superior to placebo for relief of constipation, and although a statistically significant improvement in abdominal discomfort/pain was observed compared with baseline, there was no associated improvement compared with placebo. PEG 3350 + E is a well-established and effective treatment that should be considered suitable for use in IBS-C.