Medications for hepatic encephalopathy: Nursing pharmacology

Hepatic encephalopathy refers to a life-threatening condition characterized by liver dysfunction, so the liver is unable to metabolize toxic substances, like ammonia, which is mainly produced in the gastrointestinal tract by the bacterial flora. As a result, these toxic substances can build up and travel to the brain, ultimately causing brain dysfunction. These clients can present with symptoms like insomnia or hypersomnia, mood changes, asterixis or flapping tremor, confusion, and even coma.

The two medications most commonly used to treat hepatic encephalopathy include lactulose, which is an osmotic laxative; and rifaximin, which is an antibiotic.

Okay, so lactulose is an indigestible and non-absorbable synthetic sugar that can be given orally or rectally. Once administered, lactulose gets broken down by the intestinal bacterial flora into lactic acid and short-chain fatty acids like acetic acid. These acidic metabolites partially dissociate to release hydrogen ions, which convert the ammonia generated into ammonium ions that get excreted in the stools.

Additionally, since lactulose is indigestible and non-absorbable, it stays in the lumen and pulls out water from the intestinal cells via osmosis. This lubricates the stool and helps it move faster through the gastrointestinal tract, leaving less time for the ammonia to be produced or absorbed.

Now, common side effects of lactulose include abdominal cramps, bloating, and flatulence, due to the production of methane by the intestinal bacteria that break down lactulose. In addition, lactulose can cause diarrhea, which can further lead to dehydration and electrolyte disturbances, such as hypernatremia and hypokalemia; and severe cases may result in arrhythmias. Finally, lactulose should be used with caution in clients with intestinal obstruction. Additional precautions should be taken during pregnancy and breastfeeding, as well as in elderly or debilitated clients, and in those with diabetes mellitus, as it may affect their blood glucose levels.

Next, rifaximin is administered orally, and since it is a poorly absorbable antibiotic, it primarily acts on the ammonia-producing bacteria in the gastrointestinal tract, stopping their growth. As a result, the production of ammonia in the colon is reduced.

Common side effects of rifaximin include abdominal pain, nausea, constipation, and flatulence. In addition, rifaximin may allow certain bacteria like Clostridioides difficile to survive and invade the gastrointestinal tract, rarely but potentially leading to diarrhea and Clostridioides difficile infection or CDI for short.

Often, clients taking rifaximin may also experience dizziness, headaches, insomnia, and pyrexia, while some may also develop a skin rash, photosensitivity, and exfoliative dermatitis. Some additional side effects include proteinuria and polyuria, as well as hypotension, peripheral edema, and ascites. Finally, rifaximin should be used with caution during pregnancy and breastfeeding, as well as in children and elderly clients.