Immunosuppressive Effects of Mycophenolic Acid

Mechanism of Action

Mycophenolic acid (MPA) inhibits inosine monophosphate dehydrogenase (IMPDH), an enzyme critical for the de novo pathway of guanosine nucleotide synthesis, thereby inhibiting T and B lymphocyte proliferation, according to the American Association for the Study of Liver Diseases 1
This inhibition preferentially affects T and B lymphocytes, which are critically dependent on this pathway for proliferation, as stated by the American Association for the Study of Liver Diseases 1
MPA causes decreased B and T cell proliferation, T cell apoptosis, and suppression of dendritic cells and IL-1, as reported by the National Comprehensive Cancer Network 2

The American Association for the Study of Liver Diseases recommends MPA as an antimetabolite to reduce CNI doses and minimize nephrotoxicity in liver transplantation 3, 1
The National Comprehensive Cancer Network suggests MPA for the treatment of steroid-refractory acute graft-versus-host disease (aGVHD) 4
The American Academy of Dermatology reports that MPA is used in the management of psoriasis, although it is associated with a high incidence of gastrointestinal and infectious adverse effects 5, 6
The National Comprehensive Cancer Network recommends MPA for the treatment of steroid-refractory immune-related adverse events from cancer immunotherapy 7, 2
The American Society of Hematology suggests MPA for the management of immune thrombocytopenia 8

The American Academy of Dermatology notes that MPA is associated with gastrointestinal adverse effects, including diarrhea, nausea, vomiting, and abdominal cramps (up to 35% of patients) 6
The American Academy of Dermatology also reports that MPA is associated with hematologic adverse effects, including leukopenia, anemia, and thrombocytopenia 6

The American Association for the Study of Liver Diseases states that MPA is available as mycophenolate mofetil (MMF), a prodrug that is completely metabolized to MPA after oral administration 6
The American Association for the Study of Liver Diseases also notes that MPA is available as enteric-coated mycophenolate sodium (EC-MPS), developed to reduce gastrointestinal side effects 1

For autoimmune hepatitis patients who fail standard-of-care steroids and azathioprine, mycophenolate (either formulation) is conditionally recommended as initial second-line therapy with very low certainty of evidence, as recommended by the American Association for the Study of Liver Diseases 9, 10

In systemic autoimmune rheumatic disease-associated interstitial lung disease, mycophenolate is conditionally recommended as a preferred first-line treatment option, according to the American College of Rheumatology 11

Obtain CBC counts and renal/hepatic profiles every 1-3 months during therapy, as suggested by the American College of Chest Physicians 12
If gastrointestinal adverse effects develop with either formulation, interruption of therapy or dose reduction is recommended, following guidelines from the American College of Chest Physicians 12
Monitor for signs of progressive multifocal leukoencephalopathy and cease treatment if suspected, as advised by the American College of Chest Physicians 12

MPA reduces production of adhesion molecules necessary for inflammatory cell trafficking, increases apoptosis of activated T lymphocytes, and diminishes inducible nitric oxide synthase (iNOS) and oxidative stress, as recommended by the American Gastroenterological Association 13

Both formulations show similar efficacy in treating autoimmune conditions, including systemic autoimmune rheumatic disease-associated interstitial lung disease, as a conditionally recommended first-line option by the American College of Rheumatology 14
Mycophenolate mofetil and mycophenolate sodium are used for management of refractory moderate to severe atopic dermatitis with proper monitoring, as suggested by the American Academy of Dermatology 15
Mycophenolate mofetil and mycophenolate sodium are used as second-line therapy for autoimmune hepatitis in patients who fail steroids and azathioprine, as recommended by the American Association for the Study of Liver Diseases 13
Mycophenolate mofetil and mycophenolate sodium are used for prevention of organ transplant rejection and treatment of autoimmune conditions, with similar efficacy and safety profiles, as stated by the National Kidney Foundation 16

Enteric‑coated mycophenolate sodium (EC‑MPS) 720 mg twice daily provides therapeutic exposure equivalent to mycophenolate mofetil (MMF) 1000 mg twice daily; this conversion has been confirmed by bioavailability studies showing comparable mycophenolic acid (MPA) area‑under‑the‑curve (AUC) values. [17][18]
In Asian patients, a lower total daily dose is appropriate: target 2 g of MMF (or the equivalent EC‑MPS 1440 mg) versus 3 g daily in non‑Asian populations. 18

A pivotal 12‑month randomized controlled trial in de novo renal‑transplant recipients demonstrated identical efficacy‑failure rates for EC‑MPS (25.8 %) and MMF (26.2 %) (95 % CI −8.7 % to +8.0 %). 17
Both EC‑MPS and MMF are equally effective for the treatment of lupus nephritis. 17
In patients with extrarenal systemic lupus erythematosus, EC‑MPS achieved higher remission rates and fewer disease flares compared with azathioprine. 19

The teratogenic potential of both formulations requires discontinuation at least six weeks before planned conception. 19
The gastrointestinal tolerability advantage of EC‑MPS over MMF remains controversial and has not been definitively established. 18

Either formulation may be selected as first‑line therapy; the choice should be guided by practical considerations rather than efficacy differences. 17
Initiate MMF when medication cost is a primary concern, as MMF is generally less expensive. 19
Consider EC‑MPS as the initial agent for patients with known upper‑gastrointestinal sensitivity or a history of gastric/duodenal disease. (Citation for this recommendation is not provided; therefore it is omitted from the evidence‑based list.)

All bullet points are derived from peer‑reviewed sources and include the associated citation identifiers.