Not absorbed from the gastrointestinal tract as there is no transport mechanism and no enzyme to hydrolyze it into its constituent monosaccharides. It therefore exerts an osmotic effect by drawing fluid from the bowel or retaining fluid already in the bowel. Its mechanism of action may also be due to metabolism of lactulose by gut bacteria into compounds such as lactic acid and other short chain fatty acids which may exert an osmotic effect and stimulate the bowel. Gas may be formed as part of this bacterial fermentation and may account for the side-effects of bloating and flatulence, features similar to that experienced in lactose intolerance (therefore avoid in suspected bowel obstruction).
- 10-20ml 2-3 times/day
- 30-50ml 3 times/day in hepatic encephalopathy