Psychophysiologic responses to a realistic laboratory abdominal pain stimulus.
Small doses of the carbohydrate lactulose are widely used in the clinical setting to assess small bowel transit time because lactulose is not absorbed by the small intestine and its arrival in the intestine can be detected non-invasively by breath hydrogen testing. In this study, doses of this safe, widely used substance higher than those typically administered for transit tests were given to 12 healthy young adult men to produce symptoms of gas and intestinal distention similar to those commonly experienced by patients with irritable bowel syndrome and recurrent abdominal pain. Comparison of subjective and physiological responses to the administration of 0 and 30 g of lactulose in a double-blind placebo-controlled trial demonstrated that the 30 g lactulose dose produced significant increases in a number of measures reflecting the intra-intestinal pain stimulus. The results of the present study indicate that lactulose is a realistic and ethically acceptable stimulus for the production of transient mild abdominal pain in the laboratory.