Mycophenolate Mofetil MMF
All patients receiving a kidney and/or pancreas graft should be treated with MMF in the first instance. If they are unable to tolerate it, a switch to Mycophenolic Acid (Myfortic) or Azathioprine may be made.
500 mg to 1g twice daily, depending on concomitant immunosuppression and renal function.
MMF is best absorbed on an empty stomach, either one hour before or two hours after a meal, but gastrointestinal side effects may be alleviated by taking it with food and further splitting the daily dose.
Mode of action:
MMF is rapidly hydrolysed following absorption to mycophenolic acid (MPA), the active metabolite. MPA is a potent inhibitor of inosine monophosphate dehydrogenase (IMPDH) and therefore inhibits the de-novo pathway of guanosine nucleotide synthesis. B and T lymphocytes are critically dependent on the de novo pathway and so MPA inhibits B and T lymphocyte proliferation and also B-cell antibody formation.
MMF is available as 250 mg capsules (blue-brown) and 500 mg tablets (lavender). The brand name is CELLCEPT. The equivalent doses of MYFORTIC are 180mg and 360mg respectively.
Monitoring of MMF blood levels is not needed.
Pregnancy – see important information on the Long Term Immunsuppression page.
Gastrointestinal side-effects are common. Consider an an alternative cause of diarrhoea and exclude infection. If felt to be due to MMF, consider:
- Splitting dose to 500mg qds is the first line approach
- Switching to Myfortic (720mg bd = 1g MMF bd)
- Reducing dose
- Switch to azathioprine
Leucopenia may occur. Exclude CMV infection. Consider a dose reduction and monitor white cell count.
- Tacrolimus increases the AUC of MPA, the active metabolite of MMF. By 3 months past transplant the increase is such that the dose of MMF may need to be reduced with time post-transplant to maintain stable systemic exposure to MPA.
- Cholestyramine and antacids – may bind MMF and significantly reduce absorption.
- Drugs which undergo tubular secretion, e.g. acyclovir, theoretically may impair secretion of MMF and have raised blood levels themselves during concurrent administration.
- Drugs which interfere with entero-hepatic recirculation may reduce the efficacy of MMF.