AZITHROmycin/Rifampin Oral Suspension (Anhydrous)
AZITHROmycin/Rifampin is a compounded formulation containing AZITHROmycin, Rifampin, prepared by Mixlab for veterinary use. Available by prescription.
How to Give Anhydrous Oral Suspension
Oral Suspension (Anhydrous) is a liquid medication that does not contain water in its base. This might be an oil-based or other special base to help stabilize the medicine. It will look like a regular liquid medication, but often needs a good shake because the drug can settle. Here's how to give it:
- Shake well each time to mix the medication (5-10 seconds).
- Measure the dose using the syringe/dropper provided or one recommended by your vet. Insert the top of the oral syringe into the bottle adapter. Turn the bottle upside down and pull the plunger until the medicine reaches the volume required
- Hold your pet steady: a towel or helper can assist with squirmy pets.
- Administer the dose slowly into the side of the mouth. Allow small pauses if needed for swallowing.
- Raise the head slightly to help the medication go down and clean any spills with a little water or tissue.
- Praise your pet and offer a treat or water (unless advised against feeding right after).
- Clean the syringe with water immediately after use. Store the bottle as directed, out of sunlight.
- Consistency is key: Shake each time, measure accurately, and contact your vet if any issues arise.
This compounded formulation combines azithromycin, a macrolide antibiotic, with rifampin, an antibiotic — two different drug classes. In compounding practice, clinicians may consider a combination like this for a multi-targeted approach. Your veterinarian determines whether it is appropriate based on your animal's diagnostic findings.
At a pharmacological level, this medication functions through dual-action inhibition. Azithromycin binds to the 50S ribosomal subunit of susceptible microorganisms, which may help address the process of translocation and inhibits RNA-dependent protein synthesis. Rifampin acts by inhibiting the DNA-dependent RNA polymerase enzyme in the bacterial cell, which may help address the transcription of RNA and may help reduce the synthesis of essential proteins. This combination is particularly valued in veterinary medicine because both medications are lipophilic and achieve high concentrations within macrophages, the very cells where certain bacteria typically survive and replicate. Your veterinarian will determine the clinical appropriateness of this combination based on your pet's age, weight and the results of diagnostic testing.
This description reflects the general pharmacology of the active ingredient's drug class; your veterinarian determines whether this approach is appropriate for your animal.
Prescription only. Use only under the direction of a licensed veterinarian. This information is not a substitute for veterinary diagnosis, prescribing or monitoring. Compounded drugs are not approved by the FDA for safety or effectiveness.
Commonly observed effects of azithromycin/rifampin administration include gastrointestinal changes, with mild to moderate loose stools being a frequent clinical consideration. A unique and characteristic of rifampin is its ability to cause a reddish-orange discoloration of the patient's urine, tears and saliva; while this may appear startling, it is a non-harmful physiological event associated with the medication's distribution. Owners should monitor for more significant digestive upset or a decrease in appetite and contact their veterinarian promptly with any concerns.
This medication is typically used with extra caution or avoided in patients with known severe liver disease, as both active ingredients are processed through hepatic pathways. A significant safety consideration is the risk of hyperthermia (overheating) in foals; veterinarians often discuss environmental management, such as providing shade and cooling, for patients receiving this protocol. Rifampin is also a potent inducer of hepatic enzymes, which can influence the metabolism of other concurrent prescriptions. Before starting use, ensure your veterinarian has a complete history of all other medications your pet is receiving. Your veterinarian is the right person to provide guidance on the necessary duration of use and the proper monitoring schedule to ensure the management approach remains suitable for your pet's individual needs.
Yes. Azithromycin/rifampin is a combination prescription medication and can only be dispensed by a licensed pharmacy upon receipt of a valid authorization from a licensed veterinarian. Mixlab verifies all authorizations before any medication is prepared or shipped to your home.
Yes. Because this specific two-drug combination is not available as a single commercial product, Mixlab specializes in compounding it into customized strengths and flavored dosage forms—such as oral pastes or liquids—to suit the specific needs of foals and horses. The decision to use a compounded formulation rests with the prescribing veterinarian.
The orange or reddish discoloration of urine and other body fluids is a known and effect of rifampin. This occurs because the medication itself is highly pigmented and is naturally excreted by the body in this manner; it is not typically a cause for clinical concern but should be noted as part of the management protocol.
Veterinarians frequently advise that foals receiving this combination be kept in shaded, well-ventilated environments, especially during periods of high heat. This is because the medication is associated with a risk of hyperthermia, so monitoring your pet's comfort and providing adequate cooling is an essential part of the care plan directed by your veterinarian.
