Mycophenolate mofetil (MMF), an ester prodrug of the immunosuppressant mycophenolic acid (MPA), is widely used for maintenance immunosuppressive therapy and prevention of renal allograft rejection in renal transplant recipients. MPA inhibits inosine monophosphate dehydrogenase (IMPDH), an enzyme involved in the “de novo” synthesis of purine nucleotides, thus suppressing both T-cell and B-cell p...

We developed a rapid, simple, and sensitive high-performance liquid chromatography method with UV detection for the quantitative determination of mycophenolic acid (MPA) in human plasma. MPA and the internal standard (naproxen) were separated using a mobile phase of 0.04 M H(3)PO(4)-acetonitrile-methanol (3:3:4 v/v/v) over a CAPCELL PAK C18 MG column. A flow-rate of 0.5 ml/min was used at ambie...

Mycophenolic acid (MPA; 1,3-dihydro-4-hydroxy-6-methoxy-7-methyl-3-oxo-5-isobenzylfuranyl)-4-methyl-4-hexenoate), the active metabolite of the immunosuppressant prodrug, mycophenolate mofetil, undergoes glucuronidation to its 7-O-glucuronide as a primary route of metabolism. Because differences in glucuronidation may influence the efficacy and/or toxicity of MPA, we investigated the MPA UDP-glu...

Amdoxovir [( )-D-2,6-diaminopurine dioxolane (DAPD)] is a nucleoside analogue reverse transcriptase inhibitor of human immunodeficiency virus type 1 (HIV-1) replication. DAPD is deaminated by adenosine deaminase to the guanosine analogue dioxolane guanosine (DXG), which is subsequently phosphorylated to the corresponding 5 triphosphate (DXG-TP). DXG-TP competes with the natural substrate dGTP f...

BACKGROUND/AIMS Diarrhea developing in patients under immunosuppression has a variety of underlying causes. A broad spectrum of histological findings can be found in intestinal biopsies taken for the diagnostic workup of diarrhea including a pathologically increased proportion of epithelial cell apoptosis in the colon, for which the descriptive term 'apoptotic colonopathy' was coined. In recent...

It is currently being debated whether pharmacokinetic monitoring of mycophenolic acid (MPA), the active constituent of mycophenolate mofetil (MMF), can optimize MMF therapy after organ transplantation. This open-label longitudinal study in pediatric renal transplant recipients was designed to investigate the pharmacokinetic (PK)/pharmacodynamic relationship of total and free MPA and to establis...

Mycophenolic acid has gained widespread acceptance as the antimetabolite of choice in most of the immunosuppressive regimens, thanks to its selective action versus T and B cells. This drug is characterized by a narrow therapeutic index and a well-documented relationship between efficacy (in terms of acute rejection episodes) and exposure to mycophenolic acid (as AUC and C0). For these reasons, ...

Pharmacodynamic monitoring of the biological effect of immunosuppressive drugs provides an alternative to traditional therapeutic drug monitoring. We chose this method to investigate mycophenolic acid (MPA), an immunosuppressive drug that mediates its effect by inhibition of IMP dehydrogenase (IMPDH), a key enzyme in the de novo biosynthesis of purines. Using an assay developed for measuring IM...

The RNA guanylyltransferase (GTase) is involved in the synthesis of the (m7)Gppp-RNA cap structure found at the 5' end of eukaryotic mRNAs. GTases are members of the covalent nucleotidyl transferase superfamily, which also includes DNA and RNA ligases. GTases catalyze a two-step reaction in which they initially utilize GTP as a substrate to form a covalent enzyme-GMP intermediate. The GMP moiet...

The goal of this study was to determine the roles of the organic anion-transporting polypeptides (OATPs) OATP1A2, OATP1B1, and OATP1B3 and their genetic variants in the pharmacokinetics of the immunosuppressive drug mycophenolate mofetil (MMF). Using OATP-transfected human embryonic kidney (HEK) cells, we measured the uptake of mycophenolic acid (MPA) and its glucuronide (MPAG). MPAG, but not M...