There were 8 RCTs (number of patients enrolled, n=777) of PEG, 11 RCTs (n=717) of lactulose, 10 RCTs (n=849) of irritant and stimulant laxatives, 17 RCTs (n=1,217) of bulk laxatives, 3 RCTs (n=293) of cisapride, 1 RCT (n=12) of colchicine, 1 RCT (n=9) of misoprostol, 4 RCTs (n=296) of stool softeners and 1 RCT (n=1,116) of tegaserod. Some studies compared more than two treatments.
Grade A recommendations.
There was good evidence for the use of PEG (an osmotic laxative) from 5 placebo-controlled RCTs (quality scores ranged from 3 to 5).
There was good evidence that PEG was superior to lactulose from 2 RCTs (quality scores 4 and 5).
There was good evidence for the use of tegaserod from 1 large RCT (quality score 5).
Grade B recommendations.
There was moderate evidence for the use of lactulose (an osmotic laxative) from 3 placebo-controlled RCTs (quality scores 3 or 4).
There was moderate evidence for the use of psyllium (a bulk laxative) from 3 placebo-controlled RCTs (quality scores 3 or 4).
Grade C recommendations.
There was limited evidence for other bulk laxatives (calcium polycarbophil, bran and methylcellulose), the wetting agent dioctyl sulfosuccinate, and some stimulant laxatives (senna, bisacodyl and one unnamed irritant laxative).