Mycophenolate mofetil (MMF, CellCept) is an ester prodrug of mycophenolic acid (MPA), a Penicillium-de-rived immunosuppressive agent (see Chapter 57) that blocks de novo purine synthesis by noncompetitively inhibiting the enzyme inosine monophosphate dehydro-genase. MPA preferentially suppresses the proliferation of cells, such as T and B lymphocytes, that lack the purine salvage pathway and must synthesize de novo the guanosine nucleotides required for DNA and RNA synthesis. MPA has been used for decades as a systemic treatment for moderate to severe psoriasis. MMF was developed to increase the bioavailability of MPA.
MMF is rapidly and completely cleaved to form MPA, the active metabolite, after oral administration. MPA is converted in the liver and kidney to an inactive glucuronide. However, certain tissues, such as the epidermis, express a glucuronidase that converts the inactive glucuronide back to the active agent. The half-life of MPA is approximately 18 hours; 90 to 95% of the my-cophenolate dose is excreted in the urine.
MMF is indicated for the prophylaxis of organ rejection in patients receiving renal, hepatic, and cardiac transplants; it is often used in combination with other immunosuppressive agents for this indication. In dermatology, MMF is particularly useful as monotherapy, or as a steroid-sparing agent, for treatment of autoimmune blistering diseases (bullous pemphigoid and pemphigus). It may also be useful for the treatment of inflammatory skin diseases mediated by neutrophilic infiltration, such as pyoderma gangrenosum, and psoriasis.
The principal advantage of MMF over alternative systemic immunosuppressive agents (e.g., methotrexate, cyclosporine) is its relative lack of hepatotoxicity and nephrotoxicity. Adverse effects produced by MMF most commonly include nausea, abdominal cramps, diarrhea, and possibly an increased incidence of viral and bacterial infections. Whether MMF may be associated with an increased long-term risk of lymphoma or other malignancies is controversial; however, any such risk is likely to be lower in patients treated for skin disease with MMF monotherapy than in transplant patients treated with combination immunosuppressive therapy.
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Do You Suffer From the Itching and Scaling of Psoriasis? Or the Chronic Agony of Psoriatic Arthritis? If so you are not ALONE! A whopping three percent of the world’s populations suffer from either condition! An incredible 56 million working hours are lost every year by psoriasis sufferers according to the National Psoriasis Foundation.