Comparison of orocaecal transit times assessed by the lactulose/breath hydrogen and the sulphasalazine/sulphapyridine methods.

The lactulose/breath hydrogen and the sulphasalazine/sulphapyridine methods of assessing orocaecal transit time have been compared. In a two part crossover study in healthy normal subjects the median orocaecal transit time by the SLZ/SP method was 4.84 hours but only 2.92 hours by the lactulose/breath hydrogen method. Coadministration of lactulose and sulphazalazine to nine subjects with assessment of orocaecal transit time by hydrogen breath determination and plasma sulphapyridine assay gave orocaecal transit times of 2.33 and 2.25 hours respectively suggesting that the lactulose reduces transit time and that the lactulose/breath hydrogen method, which is so convenient to use, gives artificially low transit times. A third experiment was undertaken to compare the orocaecal transit times after 1.5 and 3.0 g sulphazalazine. The orocaecal transit times after the two doses were not statistically different.