title: Mycophenolic acid clinical pharmacokinetics influenced by a cyclosporine C2 based immunosuppressive regimen in renal allograft recipients.
abstract: Therapeutic drug monitoring of mycophenolic acid (MPA) in combination with cyclosporine 2-h concentration (CsA C2, n = 68) or tacrolimus trough concentration (n = 10) was investigated by repeated measurements of MPA and MPA-glucuronide (MPAG) trough concentrations in renal allograft recipients during the first 3 months post-transplant. The acute rejection rate was lower (19% vs. 43%; P < 0.05) in patients achieving CsA C2 target range during the first week (1600-2000 microg/l), n = 26, compared with those who did not, n = 42. Median MPA concentration was 0.9 and 1.2 microg/ml in patients within or below C2 range, respectively (P = 0.19). CsA C2 correlated with MPAG-to-MPA ratio (P < 0.01, r = 0.91) and gamma-glutamyl-transpeptidase (GGT, P < 0.01, r = 0.86). Total MPA concentration increased during the 3 months, but not in patients on tacrolimus. High CsA C2 lowered the acute rejection rate and plasma MPA. High CsA C2 is associated with elevated GGT, probably because of cholestatic effects, which explain the increased MPAG-to-MPA ratio. Increasing MPA concentration is ascribed to per-protocol CsA C2 reductions. In conclusion, CsA may confound the relationship between MPA and the incidence of rejection, and contribute to the difficulty of obtaining a therapeutic range for MPA in clinical practice.
authors.affiliation: Department of Medical Biochemistry, Rikshospitalet University Hospital, Oslo, Norway.
authors.forename: Randeep
authors.initials: R
authors.lastname: Mandla
authors.forename: Karsten
authors.initials: K
authors.lastname: Midtvedt
authors.forename: Pål-Dag
authors.initials: PD
authors.lastname: Line
authors.forename: Anders
authors.initials: A
authors.lastname: Hartmann
authors.forename: Stein
authors.initials: S
authors.lastname: Bergan
mesh_terms: D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D016572:Cyclosporine / Q000627:therapeutic use*; D004347:Drug Interactions; D004359:Drug Therapy, Combination; D005260:Female; D006650:Histocompatibility Testing; D006801:Humans; D007166:Immunosuppressive Agents / Q000493:pharmacokinetics / Q000627:therapeutic use; D016030:Kidney Transplantation / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D009173:Mycophenolic Acid / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D012086:Reoperation
chemical_list: D000305:Adrenal Cortex Hormones; D007166:Immunosuppressive Agents; D016572:Cyclosporine; D009173:Mycophenolic Acid