title: What is the intrapatient variability of mycophenolic acid trough levels?
abstract: TDM of MPA, the active compound of MMF, is rarely used despite its substantial intra- and interpatient variability. Little is known about the utility of long-term MPA TDM. Data are expressed as mean (one standard deviation). All available data from 27 renal transplant recipients (mean age at transplantation: 7.7 [5.0] yr) with an average follow-up of 9.3 (4.6) yr were analyzed. MPA levels were measured using the EMIT. GFR was measured using cystatin C and eGFR was calculated using the Filler formula. Intrapatient CV of the trough level was calculated as the ratio of the mean divided by one standard deviation. Mean cystatin C eGFR was 56.9 (24.4) mL/min/1.73 m(2) . There was a weak but significant correlation between the MPA trough level and the AUC (Spearman r = 0.6592, p < 0.0001). A total of 1964 MPA trough levels (73 [45]/patient) were measured, as compared to 3462 Tac trough levels (144 [71]/patient). The average MPA trough level was 3.01 (1.26) mg/L and the average trough Tac level was 7.3 (1.8) ng/mL. Intrapatient CV was statistically higher (p = 0.00093) for MPA at 0.68 (0.29) when compared to Tac with a CV of 0.46 (0.12). CV did not correlate with eGFR. Intrapatient MPA trough level CV is significantly higher than for Tac, while CV for both MPA and Tac was high. MPA trough level monitoring may be a feasible monitoring option to improve patient exposure and possibly outcomes.
authors.affiliation: Department of Pediatrics, Schulich School of Medicine & Dentistry, London, ON, Canada.
authors.forename: Ekaterina K
authors.initials: EK
authors.lastname: Todorova
authors.affiliation: Department of Pathology and Laboratory Medicine, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada.
authors.forename: Shih-Han S
authors.initials: SH
authors.lastname: Huang
authors.affiliation: Department of Pediatrics, Schulich School of Medicine & Dentistry, London, ON, Canada.
authors.forename: Marta C
authors.identifier: http://orcid.org/0000-0002-4568-1730
authors.initials: MC
authors.lastname: Kobrzynski
authors.affiliation: Department of Pediatrics, Schulich School of Medicine & Dentistry, London, ON, Canada.|Department of Pathology and Laboratory Medicine, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada.|Department of Medicine, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada.
authors.forename: Guido
authors.initials: G
authors.lastname: Filler
mesh_terms: D000293:Adolescent; D019540:Area Under Curve; D015415:Biomarkers / Q000097:blood; D002648:Child; D002675:Child, Preschool; D016903:Drug Monitoring; D005500:Follow-Up Studies; D006084:Graft Rejection / Q000517:prevention & control*; D006801:Humans; D007166:Immunosuppressive Agents / Q000493:pharmacokinetics* / Q000627:therapeutic use; D016030:Kidney Transplantation; D009173:Mycophenolic Acid / Q000031:analogs & derivatives* / Q000097:blood* / Q000493:pharmacokinetics / Q000627:therapeutic use; D012189:Retrospective Studies
chemical_list: D015415:Biomarkers; D007166:Immunosuppressive Agents; D009173:Mycophenolic Acid
keywords: kidney transplantation; mycophenolate mofetil; outcome; pediatric; therapeutic drug monitoring