Lactulose is used to decrease intestinal ammonia absorption in patients with liver disease and hepatic encephalopathy.

• A. Increase intestinal ammonia production
• B. Treat dehydration
• C. Decrease intestinal ammonia absorption
• D. Promote potassium loss

Answer: (C)

Lactulose works by lowering the amount of ammonia that is absorbed from the gut. It’s a nonabsorbable sugar that, when it reaches the colon, is fermented into acids by bacteria. This acidifies the colonic lumen, which converts ammonia (NH3) to ammonium (NH4+). Ammonium is poorly absorbed, so more of the ammonia stays in the stool and is excreted, reducing blood ammonia levels and helping in hepatic encephalopathy.

So the best choice reflects the goal of decreasing intestinal ammonia absorption. Increasing ammonia production would worsen encephalopathy, treating dehydration is not the primary purpose here, and promoting potassium loss is not an intended effect of lactulose. Common side effects include diarrhea and dehydration, so monitoring fluid and electrolytes is important.