Which medications are used to lower blood ammonia in hepatic encephalopathy?

Which medications are used to lower blood ammonia in hepatic encephalopathy?

• A. Lactulose and rifaximin
• B. Metformin and insulin
• C. Antacids
• D. Vitamin K

Answer: (A)

Lowering ammonia levels from the gut is central to treating hepatic encephalopathy. Lactulose works by acidifying the colon, which converts ammonia (NH3) to ammonium (NH4+). Ammonium is less readily absorbed, so it stays in the gut and is excreted, and the laxative effect also reduces the time for ammonia production. Rifaximin is a nonabsorbable antibiotic that lowers the amount of ammonia produced by gut bacteria, further reducing systemic ammonia levels. Together, they directly target the mechanism driving encephalopathy and improve mental status; lactulose is typically first-line, with rifaximin added for recurrent or more severe cases. Metformin and insulin address glucose control, not ammonia. Antacids don’t meaningfully lower ammonia levels, and vitamin K corrects coagulation defects related to liver disease but not ammonia.

Lowering ammonia levels from the gut is central to treating hepatic encephalopathy. Lactulose works by acidifying the colon, which converts ammonia (NH3) to ammonium (NH4+). Ammonium is less readily absorbed, so it stays in the gut and is excreted, and the laxative effect also reduces the time for ammonia production. Rifaximin is a nonabsorbable antibiotic that lowers the amount of ammonia produced by gut bacteria, further reducing systemic ammonia levels. Together, they directly target the mechanism driving encephalopathy and improve mental status; lactulose is typically first-line, with rifaximin added for recurrent or more severe cases.

Metformin and insulin address glucose control, not ammonia. Antacids don’t meaningfully lower ammonia levels, and vitamin K corrects coagulation defects related to liver disease but not ammonia.