Erythromycin Oral

What is erythromycin?

Erythromycin (brand names: Gallimycin®, Ery-Tab®, Ery-Ped®, E.E.S., ERYC®, Emycin®, Erybid®, Erythro®, Erythrocin®, PCE®) is a macrolide antibiotic used to treat certain bacterial infections, most commonly Rhodococcus equi infections in foals. It also acts as a prokinetic used to increase the movement of the gastrointestinal tract. Today, it is not commonly used in species other than horses. 

Its use in horses, cats, dogs, ferrets, and birds to treat infections or gastrointestinal mobility problems is off label (extra label). 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 is erythromycin given?

• Erythromycin is given by mouth in the form of a capsule, tablet, or liquid. It can also be given as an injection in the hospital.
• Give this medication on an empty stomach.
• If vomiting, lack of appetite, or diarrhea occur, give future doses with food.
• Measure liquid forms of this medication carefully.

This medication will take effect quickly, in about 1 to 2 hours, but effects may not be visible for a few days.

What if I miss giving my pet the medication?

If you miss a dose, give it when you remember, but if it is close to the time for the next dose, skip the dose you missed and give it at the next scheduled time, and return to the regular dosing schedule. Never give your pet two doses at once or give extra doses.

Are there any potential side effects?

Side effects of the oral forms of erythromycin include:

• Diarrhea
• Lack of appetite
• Vomiting

Side effects of erythromycin in foals may include:

• Abnormal temperature regulation and overheating
• Decreased appetite
• Diarrhea
• Teeth grinding

Side effects of erythromycin in adult horses may include:

• Severe diarrhea

This short-acting medication should stop working within 24 hours, although effects can be longer in pets with liver or kidney disease.

Are there any risk factors for this medication?

DO NOT USE erythromycin in:

• Pets that are allergic to it
• Pets with liver disease or dysfunction
• Rabbits, gerbils, guinea pigs, or hamsters

USE WITH CAUTION in:

• Pets with abnormal heart rhythms.
• Pets that are pregnant or lactating (likely safe, but studies in animals are lacking)
• Horses more than 4 months old
• Horses exposed to hot weather (provide shade and close observation in these environments)
• Dog breeds with the MDR1/ABCB1 gene

Some breeds of dogs (e.g., collies, sheepdogs, and collie- or sheepdog-cross breeds) are more sensitive than others to medications. This is typically due to a specific genetic mutation (MDR1/ABCB1) that makes them less able to tolerate high doses of certain medications. Use erythromycin cautiously in these cases.

Are there any drug interactions I should be aware of?

Certain medications may interact with erythromycin and so it is important to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your dog is taking before starting any new treatment.

The following medications should be used with caution when given with erythromycin:

• Alprazolam
• Azole antifungals
• Buspirone
• Chemotherapy agents
• Chloramphenicol
• Cisapride
• Clindamycin
• Cyclosporine
• Diltiazem
• Methylprednisolone
• Midazolam
• Omeprazole
• Quinidine
• Sildenafil
• Sucralfate
• Theophylline

Erythromycin may also interact with the liver parameters AST and ALT and could cause falsely elevated values.

Is any monitoring needed with this medication?

• No specific monitoring is needed while your pet is taking this medication.
• Your veterinarian may monitor your pet to be sure that the medication is working.
• Monitor your pet for adverse side effects including liver problems when using this medication long-term. If any side effects occur, stop using the medication and contact your veterinarian.

How do I store erythromycin?

• Capsules and tablets should be stored at room temperature, between 59°F and 86°F (15°C and 30°C) in tight containers and protected from light.
• Oral liquids should be refrigerated.

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.