Mycophenolic acid is an an immunosuppresant drug and potent anti-proliferative, and can be used in place of the older anti-proliferative azathioprine. It is usually used as part of triple therapy including a calcineurin inhibitor (ciclosporin or tacrolimus) and prednisolone. It is also useful in research for the selection of animal cells that express the E. coli gene coding for XGPRT (xanthine guanine phosphoribosyltransferase).
For the prophylaxis of organ rejection in patients receiving allogeneic renal transplants, administered in combination with cyclosporine and corticosteroids.
Mycophenolic acid is an antibiotic substance derived from <i>Penicillium stoloniferum</i>. It blocks de novo biosynthesis of purine nucleotides by inhibition of the enzyme inosine monophosphate dehydrogenase. Mycophenolic acid is important because of its selective effects on the immune system. It prevents the proliferation of T-cells, lymphocytes, and the formation of antibodies from B-cells. It also may inhibit recruitment of leukocytes to inflammatory sites.
Mechanism of action
Mycophenolic acid is a potent, selective, uncompetitive, and reversible inhibitor of inosine monophosphate dehydrogenase (IMPDH), and therefore inhibits the de novo pathway of guanosine nucleotide synthesis without incorporation into DNA. Because T- and B-lymphocytes are critically dependent for their proliferation on de novo synthesis of purines, whereas other cell types can utilize salvage pathways, mycophenolic acid has potent cytostatic effects on lymphocytes. Mycophenolic acid inhibits proliferative responses of T- and B-lymphocytes to both mitogenic and allospecific stimulation. Addition of guanosine or deoxyguanosine reverses the cytostatic effects of mycophenolic acid on lymphocytes. Mycophenolic acid also suppresses antibody formation by B-lymphocytes. Mycophenolic acid prevents the glycosylation of lymphocyte and monocyte glycoproteins that are involved in intercellular adhesion to endothelial cells and may inhibit recruitment of leukocytes into sites of inflammation and graft rejection.