Mycophenolate Mofetil (Rheumatology)

How it works

Its active metabolite mycophenolic acid reversibly inhibits inosine monophosphate dehydrogenase, selectively curbing the purine-dependent proliferation of activated lymphocytes that drive autoimmune inflammation.

Prescribing in practice

• It is highly teratogenic, so pregnancy must be excluded and effective contraception maintained throughout treatment and for the period after stopping specified in the MHRA pregnancy-prevention programme.
• It raises the risk of serious infection and bone marrow suppression, and carries a long-term increased risk of malignancy including skin cancer.
• Gastrointestinal intolerance is common and can often be eased by dividing doses, while the mycophenolate sodium formulation is not milligram-interchangeable.

Monitoring

Monitor full blood count and liver function periodically, more closely at initiation and after dose changes, with ongoing attention to infection.

Counselling the patient

• Reliable contraception is essential and the drug must be avoided in pregnancy unless specialist-directed.
• Report fever, sore throat or unusual bruising promptly.
• Protect skin from the sun and report new or changing skin lesions.

Evidence & guidelines

Mycophenolate mofetil is recommended in NICE and specialist rheumatology guidance as a key immunosuppressant for lupus nephritis and other connective-tissue diseases.