What is the dose and frequency of Rifaximin (Rifaximin) for treating hyperammonemia?

From the Guidelines

Rifaximin should be prescribed at a dose of 550 mg taken orally twice daily for the management of elevated ammonia levels, particularly in patients with hepatic encephalopathy. This recommendation is based on the most recent and highest quality study available, which demonstrated that rifaximin reduces the risk of recurrent hepatic encephalopathy by 58% compared to placebo 1. The medication works by reducing ammonia-producing bacteria in the intestinal tract, thereby decreasing the overall ammonia burden in patients with liver dysfunction. For acute episodes of hepatic encephalopathy, rifaximin is often used alongside lactulose for maximum effectiveness. In patients with recurrent hepatic encephalopathy, rifaximin is recommended as a long-term maintenance therapy to prevent future episodes.

Some key points to consider when prescribing rifaximin include:

• The medication is generally well-tolerated with minimal systemic absorption, reducing the risk of bacterial resistance and systemic side effects 1.
• Patients should take rifaximin consistently at the same times each day with or without food.
• It's essential to monitor ammonia levels and clinical symptoms during treatment, and dosage adjustments may be necessary for patients with severe hepatic impairment.
• Common side effects include nausea, bloating, and abdominal discomfort, but these are typically mild and transient.
• Rifaximin can be used in combination with non-absorbable disaccharides, such as lactulose, to treat patients with hepatic encephalopathy 1.
• The use of rifaximin as an adjunct to lactulose is recommended as secondary prophylaxis following more than one additional episode of overt hepatic encephalopathy within 6 months of the first one 1.

From the Research

Rifaximin Dosage and Frequency for Elevated Ammonia Levels

• The dosage of rifaximin for hepatic encephalopathy has varied, but most medical centers use a dosage of rifaximin 400 mg 3 times/day 2.
• Recent clinical trials have used 550 mg twice/day in order to improve patient compliance 2.
• In a randomized, double-blind, controlled trial, rifaximin plus lactulose was compared with lactulose alone in the treatment of overt hepatic encephalopathy, with a dosage of rifaximin 1,200 mg/day 3.

Efficacy of Rifaximin in Reducing Ammonia Levels

• Rifaximin has been effective in improving behavioral, laboratory, mental, and intellectual abnormalities in patients with hepatic encephalopathy by decreasing intestinal production and absorption of ammonia 2.
• The addition of rifaximin to lactulose treatment in treatment-resistant patients decreases the hospitalization rate among patients with hepatic encephalopathy and reduces ammonia levels 4.
• Rifaximin has been shown to be effective in reducing ammonia levels in patients with liver failure, with a significant decrease in mortality and hospital stay compared to lactulose alone 3.

Comparison with Other Treatments

• Rifaximin has been compared with lactulose in well-designed clinical studies in patients with hepatic encephalopathy, and was generally found to be equal or superior to lactulose 2.
• Lactulose and rifaximin have a proven role as measures to use for secondary prophylaxis and are the mainstay of current therapy for hyperammonemia 5.
• The use of rifaximin in combination with lactulose has been shown to be more effective than lactulose alone in the treatment of overt hepatic encephalopathy 3.