Review of

Mycophenolate mofetil (MMF) is the ester prodrug of mycophenolic acid (MPA), produced by Penicillium brevicompactum and related fungi. MPA acts through inhibition of inosine-5-monophosphate dehydroge-nase (IMPDH), a rate-limiting enzyme on the de novo pathway for guanosine nucleotide synthesis, leading to depletion of purine nucleotides.1 Lymphocytes depend upon the de novo pathway for activation and prolifera-tion, and MPA is a more potent inhibitor of IMPDH type II, expressed in activated T- and B-lymphocytes, than of IMPDH type I, expressed in most cell types. Therefore the primary immunosuppressive effect is exerted on the activation and proliferation of T- and B-lymphocytes, through depletion of purine pre-cursors of DNA synthesis. However, in vitro and i