Final answer:
The synthetic disaccharide is likely lactulose, an osmotic laxative used to treat hepatic encephalopathy by increasing water retention in the bowel and reducing blood ammonia levels.
Step-by-step explanation:
The synthetic disaccharide referred to in the question is likely lactulose, a medication that operates as an osmotic laxative and is used to treat hepatic encephalopathy, a condition that affects brain function due to severe liver disease. Lactulose is not absorbed in the gut, leading to increased water retention in the bowel, thus inducing a laxative effect.
It also reduces blood ammonia levels, which can help manage hepatic encephalopathy. While other sugars like mannitol and glucose also have osmotic diuretic effects, lactulose's specific application for hepatic encephalopathy distinguishes it in this context.