Mycophenolate mofetil

How it works

It is a prodrug of mycophenolic acid, which reversibly inhibits inosine monophosphate dehydrogenase and thereby suppresses purine synthesis in proliferating T and B lymphocytes.

Prescribing in practice

• It is teratogenic with a high risk of miscarriage and congenital malformation, so pregnancy must be excluded and effective contraception used by people of childbearing potential in line with the MHRA pregnancy-prevention requirements.
• It increases susceptibility to serious infection and is associated with bone marrow suppression and a small increased long-term risk of malignancy including skin cancer.
• Gastrointestinal upset is common and the enteric-coated mycophenolate sodium form is not directly milligram-equivalent, so do not switch formulations without dose adjustment.

Monitoring

Monitor full blood count regularly, especially in the early months, alongside vigilance for infection and skin changes.

Counselling the patient

• Use reliable contraception and never take it in pregnancy unless specialist-advised.
• Report sore throat, fever, bruising or signs of infection promptly.
• Use sun protection and report new skin lesions.

Evidence & guidelines

Mycophenolate mofetil is well established in transplantation and widely used as an immunosuppressant in autoimmune disease, supported by specialist guidance and MHRA safety advice.