Azithromycin

What is azithromycin?

Azithromycin (brand name Zithromax® or Zmax®) is a broad spectrum antibiotic used for a variety of infections. It is often combined with other drugs to treat specific infections (e.g., combined with atovaquone to treat babesiosis in dogs). Azithromycin may also have anti-inflammatory, immune-modulating, and gastrointestinal motility effects.

In cats, it is used off-label to treat upper respiratory infections, bartonellosis, cryptosporidiosis, or toxoplasmosis, and in combination with atovaquone to treat cytauxzoonosis. In dogs, it is used off-label to treat cryptosporidiosis, and in combination with atovaquone to treat babesia. It is also used for certain infections in horses, cattle, rabbits, guinea pigs, and birds.

Many drugs are commonly prescribed for off-label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions very carefully, as their directions may be significantly different from those on the label.

How do I give azithromycin to my pet?

• Azithromycin is given by mouth, in the form of a tablet or liquid suspension. It also comes in an injectable form that can be given intravenously by your veterinarian.
• Tablets are preferably given with food.
• The liquid form should be shaken before dosing and preferably given on an empty stomach.
• Measure the liquid form carefully.

This medication should take effect within one to two hours; however, effects may not be noted outwardly.

What if I miss giving my pet a dose of the medication?

If you miss a dose, give it as soon as you remember, and then wait the recommended time for the next dose, as prescribed by your veterinarian. Do not give the pet two doses at once.

Are there any potential side effects from azithromycin?

Azithromycin may cause the following side effects:

• Vomiting
• Decreased appetite
• Diarrhea

If gastrointestinal side effects occur in rabbits, rodents, or horses, stop this medication and contact your veterinarian. In dogs and cats, contact your veterinarian if gastrointestinal side effects continue for multiple days or become severe.

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 pets with liver or kidney disease.

Are there any risk factors for this medication?

DO NOT USE azithromycin in animals that:

• Are sensitive to macrolide antibiotics

USE WITH CAUTION in animals that:

• Have liver disease
• Have certain abnormal heart rhythms
• Have a history of vomiting
• Are pregnant or nursing (safety studies are limited)

Are there any drug interactions I should be aware of?

• Drug interactions with azithromycin have not been reported in animals.
• There are many classes of drugs that may interact with azithromycin as seen in human studies. Your veterinarian will weigh the potential risks when combining medications and use additional monitoring as needed.

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

Is any monitoring needed with this medication?

• 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.
• At home, monitor for any side effects such as those noted above. If any occur, stop using the medication and contact your veterinarian.

How do I store azithromycin?

• Store tablets in a tightly sealed container, protected from light, at room temperature (less than 30°C or 86°F).
• Store oral suspension (liquid form) at room temperature for up to 10 days, then discard.

What should I do in case of an 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.