Absorption of Lactulose in Man

Lactulose absorption was studied in 6 normal subjects after the administration of different doses of lactulose. Lactulose was detected in the blood of only one patient. No changes were observed in the blood levels of glucose, galactose or lactate during the 24 h of the study in any of the volunteers. The amount of lactulose excreted in the urine was less than 1 % of the administered dose in 5 subjects and 2.8% in the 6th. Lactulose was detectable in urine 2 h after ingestion. At 8 h, the excretion was almost completed, ranging by then from 77 to 100% of the total amount excreted. It is concluded that lactulose in man is absorbed and excreted only in very small amounts and is not metabolized.