Antidiarrheal effects of dihydroergotamine.

Dihydroergotamine (DHE), an alpha-adrenergic blocking agent, rapidly improved 121 out of 123 diarrheal patients. A hypotonic sigmoid and a hyperreactive rectum were found in these patients. Manometric studies of the distal colon showed that DHE counteracts the rectal hyperactivity and increases sigmoidal tone. On the other hand, anticholinergic drugs and/or emotional stimuli accentuate the rectal hyperactivity of diarrheal patients. Both features could be due to an unbalanced neurologic control of the gastrointestinal tract with dominance of the alpha-adrenergic over the cholinergic activity. Diphenoxylate (DPO) suppressed the diarrhea in two patients not improved by DHE. Furthermore, DPO reinforced the therapeutic success of DHE in 11 lactose intolerance diarrheal patients, suggesting that the two drugs exert their effects by means of different mechanisms.