The following laxative lowers blood ammonia level in hepatic encephalopathy
**Core Concept**
Lactulose is a type of disaccharide laxative used to treat hepatic encephalopathy by reducing blood ammonia levels. It works by being fermented by colonic bacteria, producing short-chain fatty acids and lactic acid, which increase the pH of the colon and favor the excretion of ammonia.
**Why the Correct Answer is Right**
Lactulose is a non-absorbable disaccharide that is fermented by colonic bacteria, producing short-chain fatty acids and lactic acid. This process increases the pH of the colon, favoring the conversion of ammonia to its less toxic form, ammonium. Ammonium is then excreted in the stool, reducing blood ammonia levels and alleviating symptoms of hepatic encephalopathy. This mechanism is essential in managing hepatic encephalopathy, a complication of liver disease characterized by cognitive disturbances and altered mental status.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not relevant to the treatment of hepatic encephalopathy or the mechanism of lactulose.
* **Option B:** This is incorrect because lactulose does not directly stimulate gut motility or affect gut transit time.
* **Option D:** This is incorrect because lactulose does not directly affect the kidneys or increase urine production.
**Clinical Pearl / High-Yield Fact**
Lactulose is a non-absorbable disaccharide laxative that works by being fermented by colonic bacteria, producing short-chain fatty acids and lactic acid, which increase the pH of the colon and favor the excretion of ammonia. This makes it an essential treatment for hepatic encephalopathy.
**Correct Answer:** C. Lactulose