Clarithromycin/Rifampin Oral Suspension (Anhydrous)
Clarithromycin/Rifampin is a compounded formulation containing clarithromycin and rifampin, prepared by Mixlab for veterinary use in horses. 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 two antimicrobial agents from different classes: clarithromycin, a macrolide and rifampin. In compounding practice, clinicians may consider a combination like this when intracellular penetration is a consideration. Your veterinarian determines whether it is appropriate based on your animal's age, weight and diagnostic testing.
At a pharmacological level, the two components act through distinct mechanisms. Clarithromycin binds to the 50S ribosomal subunit of susceptible bacteria, which inhibits bacterial protein synthesis. Rifampin inhibits bacterial DNA-dependent RNA polymerase, halting the transcription of genetic material into proteins. Clarithromycin is noted for its tissue concentration and bioavailability and rifampin is highly lipid-soluble, allowing broad tissue penetration.
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 clarithromycin/rifampin administration include gastrointestinal changes such as loose stools or mild colic. A unique physiological observation associated with rifampin is the orange or red-orange discoloration of urine, saliva and sweat, which is a harmless metabolic result of the medication’s pigment. Because clarithromycin can influence the body’s ability to regulate temperature, foals receiving this medication are at risk for hyperthermia (overheating), particularly in hot or humid environments. Owners should monitor for signs of respiratory distress, excessive panting or lethargy and ensure the patient remains in a cool, shaded environment. If you observe significant diarrhea, persistent fever or signs of physical distress, contact your veterinarian promptly.This medication is typically used with extreme caution or avoided in adult horses, as the clarithromycin component is associated with severe, potentially fatal intestinal inflammation in mature equine patients. Adult horses in contact with treated foals should be monitored closely to prevent accidental ingestion. Before starting a protocol, ensure your veterinarian has a complete history of all other prescriptions and supplements your animal is receiving, as rifampin is known to significantly alter the metabolism of other medications processed by the liver. Your veterinarian is the right person to design a comprehensive monitoring plan and provide guidance on the necessary duration of use to ensure the management approach remains suitable for your animal's health status.
Yes. Clarithromycin/rifampin is a combination of potent prescription antibiotics 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.
Yes. Since this specific combination is often required in specialized concentrations or flavored oral suspensions not available as a single commercial product, Mixlab’s compounding team can prepare it to meet your veterinarian’s exact requirements. The decision between a commercial and compounded product rests with the prescribing veterinarian.
Veterinarians discuss clarithromycin specifically for foals because their digestive systems can tolerate this class of antibiotic, whereas adult horses often develop severe and life-threatening diarrhea if they ingest even small amounts. Clinical awareness of this species-age distinction is vital for equine safety.
The orange or reddish discoloration of urine and other body fluids is a commonly observed effect of rifampin. This occurs because the medication is naturally a bright red-orange pigment, and as the body processes it, the color is safely excreted through various pathways.
This medication must never be administered to or ingested by adult horses. Clarithromycin belongs to the macrolide antibiotic class, which is associated with severe, potentially fatal intestinal inflammation in mature equine patients. Adult horses sharing an environment with a foal receiving this medication should be kept away from the treatment area and any treated feed or surfaces to prevent accidental ingestion. If adult horses are present on the property during treatment, discuss specific environmental management protocols with your veterinarian before beginning therapy.
