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What is the intrapatient variability of mycophenolic acid trough levels?
Ekaterina K Todorova1, Shih-Han S Huang2, Marta C Kobrzynski1
1Department of Pediatrics, Schulich School of Medicine & Dentistry, London, ON, Canada.
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.
Insights
Therapeutic drug monitoring for mycophenolic acid (MPA) shows high variability, suggesting it could be a useful tool for improving patient outcomes in renal transplant recipients. Long-term monitoring data indicate feasibility for clinical application.
Area of Science:
- Pharmacology
- Nephrology
- Transplantation
Background:
- Therapeutic drug monitoring (TDM) of mycophenolic acid (MPA), the active metabolite of mycophenolate mofetil (MMF), is underutilized despite significant pharmacokinetic variability.
- Limited data exist on the long-term utility and variability of MPA TDM in clinical practice.
Purpose of the Study:
- To evaluate the utility and feasibility of long-term therapeutic drug monitoring for MPA in renal transplant recipients.
- To compare the intrapatient variability of MPA trough levels with that of tacrolimus (Tac).
Main Methods:
- Analysis of retrospective data from 27 renal transplant recipients with an average follow-up of 9.3 years.
- Measurement of MPA and Tac trough levels using EMIT assay.
- Calculation of intrapatient coefficient of variation (CV) for MPA and Tac trough levels.
Main Results:
- A weak but significant correlation was observed between MPA trough levels and the area under the curve (AUC).
- Intrapatient CV for MPA trough levels (0.68) was significantly higher than for Tac (0.46).
- Despite high variability, MPA trough level monitoring is suggested as a feasible option.
Conclusions:
- Intrapatient variability of MPA trough levels is significantly higher compared to Tac, highlighting the need for monitoring.
- Long-term MPA TDM is a feasible option that may help optimize patient exposure and improve clinical outcomes in renal transplant recipients.
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