Faecal ammonia and pH during lactulose administration in man: comparison with other cathartics
L Agostini, PF Down, J Murison, OM Wrong�- Gut, 1972 - gut.bmj.com
L Agostini, PF Down, J Murison, OM Wrong
Gut, 1972•gut.bmj.comThe effect of lactulose on faecal p H and ammonia has been studied in three normal
subjects with the aid of dialysis of faeces in vivo. Observations were also made with sodium
sulphate and the two hexahydric alcohols, mannitol and sorbitol, given in doses sufficient to
cause a similar increase in stool weight. All four cathartics rendered the stool more acid, but
there was no increase in the concentration of faecal ammonia. Lactulose, despite increasing
faecal volume, did not cause an increase in the absolute amount of ammonia lost in the�…
subjects with the aid of dialysis of faeces in vivo. Observations were also made with sodium
sulphate and the two hexahydric alcohols, mannitol and sorbitol, given in doses sufficient to
cause a similar increase in stool weight. All four cathartics rendered the stool more acid, but
there was no increase in the concentration of faecal ammonia. Lactulose, despite increasing
faecal volume, did not cause an increase in the absolute amount of ammonia lost in the�…
The effect of lactulose on faecal pH and ammonia has been studied in three normal subjects with the aid of dialysis of faeces in vivo. Observations were also made with sodium sulphate and the two hexahydric alcohols, mannitol and sorbitol, given in doses sufficient to cause a similar increase in stool weight.
All four cathartics rendered the stool more acid, but there was no increase in the concentration of faecal ammonia. Lactulose, despite increasing faecal volume, did not cause an increase in the absolute amount of ammonia lost in the faeces, but the other purgatives did show a modest rise.
The results are inconsistent with the theory that lactulose benefits the clinical picture of portosystemic encephalopathy by trapping ammonia in an acid stool. An alternative suggestion is advanced, namely, that any cathartic (including lactulose) reduces ammonia absorption from the colon by decreasing colonic transit time, and so reducing the amount of ammonia generated by autolysis of colonic bacteria.
gut.bmj.com