Magnesium citrate-bisacodyl regimen proves better than castor oil for colonoscopic preparation

A clean colon preparation prior to endoscopy or X-ray examination is essential to obtain an accurate diagnosis. In order to determine which of two easily made preparations is better, this study compares colon cleansing efficacy, patient acceptance and side effects in patients given either a magnesium citrate-bisacodyl or a castor oil regimen prior to colonoscopy.

Seventy outpatients scheduled for colonoscopy were randomized to receive one of two bowel evacuation regimens on the day prior to the examination. Group 1 (n = 36) received a magnesium citrate solution (250 mL) and bisacodyl (10 mg, orally). Group 2 (n = 34) received castor oil (60 mL, orally).

The cleansing effect of the magnesium citrate-bisacodyl regimen was significantly better than that of castor oil in the ascending colon and caecum (cleansing scores 5.2+/-1.2 vs 3.5+/-1.3, P< 0.0001), but similar to that of castor oil in the recto-sigmoid, descending and transverse colon. Abdominal pain (38 vs 11%, P< 0.01) and nausea (29 vs 8%, P<0.05) were significantly more common in patients receiving the castor oil preparation than in patients administered with the magnesium citrate-bisacodyl regimen. More patients complained of poor acceptance with the castor oil regimen than with the magnesium citrate-bisacodyl regimen (24 vs 8%, P=0.06).

A combined oral magnesium citrate and bisacodyl regimen is effective and better than castor oil for colonoscopic preparation.