Comparison of efficacy and safety of two doses of two different polyethylene glycol-based laxatives in the treatment of constipation

Aim: To compare standard and maximum daily doses of polyethylene glycol 3350 plus electrolytes (Transipeg) and polyethylene glycol 4000 (Forlax) in a multicentre, double-blind, randomized, parallel-group study. Methods: Ambulatory patients with idiopathic chronic constipation were randomized to receive Forlax (10 or 20 g) or Transipeg (5.9 or 11.8 g) for 1 month. The primary efficacy end-point was stool frequency. Secondary efficacy parameters included stool consistency, date of occurrence of first motion, straining on defecation, rectal evacuation, abdominal pain and distension. Adverse events were recorded. Results: Stool frequency was significantly increased compared with baseline in all treatment groups (P = 0.0001). Most patients (greater than or equal to 67.3%) had their first stool within 1 day of starting treatment. Stool consistency significantly improved compared with baseline in all treatment groups (P = 0.0001). The percentage of patients with normal stool consistency was significantly higher for standard-dose Transipeg vs. both maximum-dose treatments (P < 0.01). Other secondary parameters were also significantly improved compared with baseline in all treatment groups (P = 0.0001). All medications were well tolerated. Conclusions: Standard-dose Transipeg (5.9 g) normalized stool consistency with less semi-liquid or liquid stools than maximum-dose Transipeg and Forlax, with a non-significant trend towards less semi-liquid or liquid stools than standard-dose Forlax.