Mycophenolate Mofetil
Mycophenolate mofetil (RS-61443)
Also known as: CellCept · Cellmune · Imuxgen · Munotras · Mycept · Myfortic · Refrat · RS-61443 · MMF · Mycophenolic acid (active metabolite) · MPA
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Immune-mediated hemolytic anemia (IMHA) | 12-17 mg/kg PO once daily or divided twice daily | PO | q12-24h | — | 🌎 NA |
| IMHA, myasthenia gravis or glomerulonephritis | 12-17 mg/kg PO once daily or divided twice daily | PO | q12-24h | — | 🌎 NA |
| Immune-mediated hemolytic anemia (IMHA) | 400-600 mg/m2 orally twice daily | PO | q12h | — | 🌎 NA |
| Adjunctive treatment of glomerulonephritis | 10-20 mg/kg PO q12h | PO | q12h | 3-4 weeks trial | 🌎 NA |
| Pemphigus foliaceous | 22-39 mg/kg/day divided into 3 daily doses | PO | q8h | — | 🌎 NA |
| Pemphigus foliaceous | 20-40 mg/kg/day PO divided q8h | PO | q8h | — | 🌎 NA |
| Aplastic anemia | 10 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Rescue agent for generalized myasthenia gravis | 500 mg (15-20 mg/kg) diluted and given IV over 2-4 hours | IV | q24h | 13 days | 🌎 NA |
- Immune-mediated hemolytic anemia (IMHA): Given with prednisolone (at 2 mg/kg q12-24h). Dogs also received ranitidine and sucralfate in the study.
- IMHA, myasthenia gravis or glomerulonephritis: Given with prednisone (at 2.2 mg/kg q12-24h).
- Immune-mediated hemolytic anemia (IMHA): Extrapolated from human medicine. Gastrointestinal side effects are common and dose limiting.
- Adjunctive treatment of glomerulonephritis: Trial of single drug therapy for 3-4 weeks recommended.
- Pemphigus foliaceous: Success rates of approx 50%; most dogs require glucocorticoids to control signs.
- Pemphigus foliaceous: Steroid-sparing only.
- Aplastic anemia: First effects observed 2 weeks later; complete remission in approx 3 weeks.
- Rescue agent for generalized myasthenia gravis: Given daily IV until swallowing oral meds, then switched to 10-11 mg/kg PO q12h.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| IMHA | 10 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
- IMHA: Use with caution due to feline glucuronidation deficiency.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Mycophenolate mofetil (MMF) is a potent immunosuppressant drug increasingly utilized in veterinary medicine as a steroid-sparing agent or rescue therapy for severe, refractory immune-mediated diseases.
Key clinical applications include:
- Immune-mediated hemolytic anemia (IMHA)
- Glomerulonephritis
- Myasthenia gravis
- Pemphigus foliaceous
- Organ transplant anti-rejection protocols
While it has been suggested for inflammatory bowel disease (IBD), its use is complicated because the drug's primary adverse effects in dogs are gastrointestinal (gastritis, diarrhea, and intestinal inflammation). Clinical Pearl: MMF is often preferred over azathioprine in some critical cases due to its relatively rapid onset of action, but its high cost and severe GI side effects can be limiting factors. Experience in cats is very limited, and it must be used with extreme caution due to feline deficiencies in glucuronidation pathways.
Mechanism of action
Mycophenolate mofetil (MMF) is a prodrug that is rapidly hydrolyzed in vivo to its active form, mycophenolic acid (MPA).
- MPA non-competitively and reversibly inhibits inosine monophosphate dehydrogenase (IMPDH).
- IMPDH is the rate-limiting enzyme in the de novo synthesis of guanosine nucleotides.
- Because T-lymphocytes and B-lymphocytes are highly dependent on this de novo purine synthesis pathway (and lack the purine salvage pathways utilized by other cell types), MPA selectively inhibits their proliferative responses.
- This leads to → suppression of B-cell antibody formation and → inhibition of leukocyte recruitment to inflammatory sites and allotransplant tissues.
Safety & warnings
Contraindications
- Documented hypersensitivity to mycophenolate
- Pregnancy (teratogenic effects noted in animal models)
- Caution in patients with severe renal dysfunction (dosage adjustment may be required)
- Caution in cats (deficient in glucuronidation metabolism)
- Pre-existing bone marrow suppression
- Pre-existing infections
Adverse effects
- Diarrhea (can be severe)
- Vomiting
- Anorexia
- Lethargy / reduced activity
- Weight loss
- Lymphopenia
- Increased rates of dermal infections
- Increased susceptibility to systemic infections
- Potential increased risk of malignancy/lymphoma
- Bone marrow suppression
- Nausea
- Diarrhoea
- Increased incidence of infections (e.g., pyoderma, Malassezia)
- Increased risk of lymphoma (reported in humans)
- Headache (reported in humans)
- Hypertension (reported in humans)
- Peripheral oedema (reported in humans)
- Confusion (reported in humans)
- Coughs (reported in humans)
- Tremors (reported in humans)
Precautions
Black Box Warning: In humans, mycophenolate carries a warning regarding a potential increased risk for lymphoma and susceptibility to infections associated with its use.
- Intravenous Administration: Must be administered over at least two hours. Do NOT give as an IV bolus or via rapid IV infusion.
- Feline Patients: The active metabolite (MPA) is primarily excreted as a glucuronide metabolite. Cats are deficient in this metabolic process; use with extreme caution.
- Pregnancy: Teratogenic (increased resorptions and malformations). Avoid use during pregnancy.
- Handling: Due to teratogenic risks, tablets or capsules should not be crushed, split, or opened. Personnel and owners should wear gloves when handling.
Drug interactions
Increased serum concentrations of acyclovir and the phenolic glucuronide of mycophenolic acid
Decreased absorption of mycophenolate; separate dosing by at least 2 hours
Potentially increased concentrations of free mycophenolic acid
Increased risk for bone marrow suppression; use together not recommended in humans
Decreased absorption of mycophenolate; separate dosing by at least 2 hours
Potentially increased serum levels of mycophenolic acid and the phenolic glucuronide of mycophenolic acid
May be less effective; avoid use
Competes for secretion, resulting in increased concentrations of either drug
Concomitant administration may decrease the absorption of mycophenolate
Monitoring
- Clinical efficacy (resolution of immune-mediated disease signs)
- Complete Blood Count (CBC) for bone marrow suppression
- Renal and hepatic function panels
- Serum electrolytes
- Gastrointestinal effects (monitor weight, appetite, and client reports of vomiting/diarrhea)
- Complete Blood Count (CBC) to monitor for bone marrow suppression
- Gastrointestinal signs (nausea, vomiting, diarrhea)
- Signs of secondary infections (e.g., skin lesions, lethargy, fever)
Pharmacokinetics
Half-life
Absorption
Absorbed orally but with wide inter-patient and inter-dose variation. Bioavailability in dogs ranges from 54-87%. In humans, oral bioavailability averages 94%, but food reduces peak levels of MPA by up to 40%.
Distribution
Volume of distribution at steady-state in dogs is approximately 5 L/kg, with wide inter-patient variability (±4.5).
Metabolism
Rapidly hydrolyzed in vivo to the active form, mycophenolic acid (MPA). MPA is primarily metabolized via glucuronidation (cats are deficient in this pathway).
Elimination
Primarily excreted in the urine, both unchanged (approx. 5%) and as the glucuronide metabolite (approx. 90%).
Overdose
In oral acute studies performed in mice and monkeys, no deaths occurred in dosages up to 4,000 mg/kg and 1,000 mg/kg, respectively. In small animals, acute gastrointestinal disturbances (severe vomiting, diarrhea) could be expected. Treatment should be symptomatic and supportive.
Available products
Formulations
- Oral capsules
- Oral tablets
- Lyophilized powder for injection
- 250 mg capsule
- 500 mg tablet
- 1 g/5 ml powder for oral suspension
- 180 mg tablet
- 360 mg tablet
- 500 mg powder for reconstitution and slow i.v. infusion
Human-labeled
- Mycophenolate Mofetil Oral Capsules: 250 mg (CellCept®)
- Mycophenolate Mofetil Oral Tablets: 500 mg (CellCept®)
- Mycophenolate Mofetil Powder for Oral Suspension: 200 mg/mL (reconstituted) (CellCept®)
- Mycophenolate Mofetil Lyophilized Powder for Injection: 500 mg in 20 mL vials (CellCept®)
- CellCept (250 mg capsule, 500 mg tablet, 1 g/5 ml oral suspension)
- Myfortic (180 mg, 360 mg tablets)
- 500 mg powder for injection
Regulatory status
Human-approved product used off-label in veterinary medicine under the cascade. POM status.
Human-approved product used off-label in veterinary medicine under the cascade. POM status.
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Tablets and capsules: Store between 15-30°C and protect from light. Oral suspension: Store powder between 15-30°C. Once reconstituted, store at room temperature or refrigerate (do not freeze); discard unused portion after 60 days. Injectable: Store between 15-30°C. Reconstitute with 5% dextrose. Do not mix with other medications. Administer within 6 hours of dilution.
Client information
- Administration: Preferably give on an empty stomach. However, if vomiting or lack of appetite occurs, you may give it with food to see if tolerance improves.
- Handling Precautions: Because this drug can cause birth defects, do not crush, split, or open capsules/tablets. Pregnant women should avoid handling this medication. Wash hands thoroughly after administration.
- Side Effects: Gastrointestinal upset is the most common side effect. Contact your veterinarian immediately if diarrhea persists, becomes severe, or if your pet stops eating.
- Infection Risk: This medication suppresses the immune system. Keep your pet away from sick animals and notify your vet if you notice signs of infection (lethargy, fever, new skin lesions).
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.