All of the following statements about mycophenolate mofetil are true except:

It is a new immunosuppressant; prodrug of mycophenolic acid which selectively inhibits inosine monophosphate dehydrogenase an enzyme essential for the de novo synthesis of guanosine nucleotides in the T and B cells (these cells, unlike others, do not have the purine salvage pathway). Lymphocyte proliferation, antibody production, and cell-mediated immunity are inhibited. As 'add on' drug to cyclosporine + glucocoicoid in renal transplantation, it has been found as good or even superior to azathioprine, but should not be combined with azathioprine. It can help to reduce the dose of cyclosporine and thus its toxicity. Vomiting, diarrhea, leucopenia, and predisposition to CMV infection, g.i. bleeds are the prominent adverse effects. ESSENTIAL of MEDICAL PHARMACOLOGY SIXTH EDITION -K D TRIPATHI Page:854