What is the intrapatient variability of mycophenolic acid trough levels?

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 e GFR 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 e GFR 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 ( S pearman r  = 0.6592, p < 0.0001). A total of 1964 MPA trough levels (73 [45]/patient) were measured, as compared to 3462 T ac trough levels (144 [71]/patient). The average MPA trough level was 3.01 (1.26) mg/L and the average trough T ac 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 T ac with a CV of 0.46 (0.12). CV did not correlate with e GFR . Intrapatient MPA trough level CV is significantly higher than for T ac, while CV for both MPA and T ac was high. MPA trough level monitoring may be a feasible monitoring option to improve patient exposure and possibly outcomes.