What is mycophenolate mofetil?
Mycophenolate mofetil (brand name CellCept®) is an immune suppressing drug used to treat various autoimmune diseases in dogs and occasionally cats. There has been minimal research on the use of mycophenolate in cats and so extra caution is warranted.
Its use in dogs and cats to treat autoimmune diseases is “off label” or “extra label”. 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 is mycophenolate given?
Mycophenolate is given by mouth as a tablet, capsule, oral suspension, or compounded liquid suspension, or it is given as an injectable solution into the vein, over at least 2 hours, in the hospital. When given by mouth, it should be given on an empty stomach. If vomiting occurs when dosed on an empty stomach, give future doses with food or a treat.
Gloves should be worn when administering this medication. Thoroughly wash hands after giving the medication. Pregnant people or those who are actively trying to conceive should use extreme caution when handling this medication, including wearing gloves and avoiding inhaling dust from capsules or tablets.
Mycophenolate should take effect after several doses. Improvement in clinical signs may not be noticeable and therefore laboratory tests may need to be done to evaluate this medication’s effectiveness.
What if I miss giving my pet the medication?
If you miss a dose, give it when you remember. However, if it is close to the time for the next dose, skip the dose you missed, 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?
The most common side effects in dogs include diarrhea, vomiting, lack of appetite, lethargy, bone marrow suppression including reduced lymphocytes (lymphopenia), papilloma formation, and skin infections (pyodermas). When this drug is given by injection, mild allergic reactions may occur. The most common side effect in cats is diarrhea. Decreased appetite, liver disease and pancreatitis have been rarely reported. When using this medication long term, there may be an increased risk of infection or cancer.
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?
Pets that are allergic to mycophenolate, mycophenolic acid, or polysorbate 80 should not use this medication. It should be used cautiously in patients with current infections or with liver or kidney disease.
Mycophenolate should not be used in pregnant or lactating animals unless it is the last resort for treatment. If used in lactating animals, milk replacer should be used.
Due to the limited information on safety and effectiveness, mycophenolate needs to be used with caution in cats.
Are there any drug interactions I should be aware of?
The following medications should not be administered with mycophenolate: azathioprine, cholestyramine or other medications that interfere with liver function; norfloxacin and metronidazole combination; rifampin; and immunosuppressive agents except corticosteroids, cyclosporine, OKT3, and antithymocyte globulin.
Medications that need to be used with caution in patients taking mycophenolate include: antiviral medications (acyclovir, valacyclovir, ganciclovir), aminoglycoside antibiotics (amikacin, gentamycin), antacids, iron supplements, lanthanum carbonate, probenecid, proton pump inhibitors (omeprazole, pantoprazole), salicyclates (aspirin, bismuth salicylate), lanthanum carbonate, and telmisartan.
Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.
Pets taking mycophenolate should not be vaccinated with modified live vaccines. Vaccinations in general may not provide sufficient protection in patients taking mycophenolate.
Is there any monitoring that needs to be done with this medication?
Complete blood counts, biochemistry, and electrolytes should be monitored throughout treatment, from every one to two weeks to every two to three months, depending on length of treatment. Your veterinarian will also monitor your pet to be sure that the medication is working.
Your pet will need to be monitored closely for signs of infection (lethargy, fever, rash, abnormal urination) and for gastrointestinal changes (inappetence, vomiting, diarrhea). Any abnormalities should be reported to your veterinarian right away.
How do I store mycophenolate?
Tablets and capsules should be stored at room temperature between 20°C and 25°C (68°F to 77°F) and protected from light and moisture. Injectable mycophenolate powder should be stored between 15°C and 30°C (59°F to 86°F). Once the powder has been reconstituted, the medication should be used within 6 hours.
What should I do in case of emergency?
If you suspect an overdose or an adverse reaction to the medication, call your veterinary office. Your veterinarian may recommend contacting an animal poison control center as well. If your veterinarian is not available, follow their directions in contacting an emergency facility.
