Rifaximin

What is rifaximin?

Rifaximin is an antibiotic drug used to treat chronic diarrhea in dogs. It may also be effective in reducing neurological signs associated with liver disease in dogs and cats. It is used to treat and prevent mastitis in cows, and to treat endometritis in cows and horses.

Rifaximin is classified as a non-systemic antibiotic, which means it works in the intestinal tract but is not absorbed in other parts of the body or bloodstream. There are no licensed veterinary versions of rifaximin available. Human formations may be prescribed for off-label use.

Many drugs are commonly prescribed for off-label use in veterinary medicine. “Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label.

How do I give my pet rifaximin?

• Rifaximin is given orally (by mouth) and comes in the form of tablets.
• This medication may also be compounded into other forms.
• This medication may be given with or without food.
• If vomiting occurs when given on an empty stomach, give the next dose with a small meal or treat.
• Follow your veterinarian’s directions and measure liquid compounded forms of this medication carefully.
• Ideally, give this medication at the same time daily.

This medication should take effect within 1 to 2 hours; however, effects may not be noted outwardly and it may take 1 to 2 days before your pet begins to feel better.

What if I miss giving my pet the medication?

If you miss a dose, give it as soon as you remember, and then continue with the regular dosing schedule. However, if it is almost time for the next dose, skip the missed dose and resume the regular dosing schedule. Do not give the pet two doses at once.

Are there any potential side effects from rifaximin?

Rifaximin may cause the following side effects:

• Nausea and drooling associated with nausea
• Low energy levels
• Water retention in the limbs, making them appear puffy and swollen

Serious adverse reactions associated with this drug may occur without warning and could, in rare cases, lead to death. If any of the following signs develop, stop giving rifaximin and contact your veterinarian immediately:

• Persistent low energy levels that do not improve
• Pale gums
• Noisy breathing
• Rash or itching
• Swelling of the lips and gums
• Collapse

Drug sensitivities can develop over time, with repeated exposure. Your pet may have no reaction after the first few doses but may develop a sensitivity later. It is important to watch for signs of an allergic reaction over the entire course of the treatment and notify your veterinarian if you have any concerns.

Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately. This short-acting medication should stop working within 24 hours, although effects can be longer in animals with liver or kidney disease.

Are there any risk factors for this medication?

DO NOT USE rifaximin in:

• Pets that are allergic to it
• Pets with bloody diarrhea
• Pets with a fever

USE WITH CAUTION in:

• Animals with decreased liver function or liver damage
• Animals that are pregnant or nursing

Are there any drug interactions I should be aware of?

The following drugs should be used WITH CAUTION when given with rifaximin:

• Cyclosporine
• CYP 3A4 inhibitors (e.g., clarithromycin, fluoxetine, ketoconazole, verapamil)
• P-glycoprotein inhibitors (e.g., amiodarone, clarithromycin, itraconazole, verapamil)
• Live or oral vaccines
• Warfarin

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking before starting any new treatment.

Is any monitoring needed with this medication?

• At home, monitor for any side effects such as those noted above. If any occur, stop using the medication and contact your veterinarian.
• Your veterinarian will let you know when and how they want to reassess your pet to ensure the medication is working and not causing side effects.

How do I store rifaximin?

• Ensure rifaximin is tightly stored in its original container in a cool, dry place, and protected from light.
• Store this medication at room temperature between 68°F and 77°F (20°C and 25°C).
• KeKeep the container out of reach of children and pets.

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility. Be prepared to provide information about the product and your pet’s weight and symptoms.