Influence of Sex and Race on Mycophenolic Acid Pharmacokinetics in Stable African American and Caucasian Renal Transplant Recipients

Background and Objectives No evaluation of sex and race influences on mycophenolic acid (MPA) pharmacokinetics and adverse effects (AEs) during enteric-coated mycophenolate sodium (ECMPS) and tacrolimus immunosuppression are available. The primary objective of this study was to investigate the influence of sex and race on MPA and MPA glucuronide (MPAG) pharmacokinetics in stable renal transplant recipients receiving ECMPS and tacrolimus Methods The pharmacokinetics of MPA and MPAG and their associated gastrointestinal AEs were investigated in 67 stable renal transplant recipients: 22 African American males (AAMs), 13 African American females (AAFs), 16 Caucasian males (CMs), and 16 Caucasian females (CFs) receiving ECMPS and tacrolimus. A validated gastrointestinal AE rating included diarrhea, dyspepsia, vomiting, and acid-suppressive therapy was completed. Apparent clearance, clearance normalized to body mass index (BMI), area under the concentration–time curve from time zero to 12 h (AUC 12 ) and dose-normalized AUC 12 (AUC*) were determined using a statistical model that incorporated gastrointestinal AE and clinical covariates. Results Males had more rapid apparent MPA clearance (CMs 13.8 ± 6.27 L/h vs. AAMs 10.2 ± 3.73 L/h) than females (CFs 8.70 ± 3.33 L/h and AAFs 9.71 ± 3.94 L/h; p = 0.014) with a race–sex interaction ( p = 0.043). Sex differences were observed in MPA clearance/BMI ( p = 0.033) and AUC* ( p = 0.033). MPA AUC 12 was greater than 60 mg·h/L in 57 % of renal transplant recipients (RTR) with 71 % of patients demonstrating gastrointestinal AEs and a higher score noted in females. In all patients, females exhibited 1.40-fold increased gastrointestinal AE scores compared with males ( p = 0.024). Race ( p = 0.044) and sex ( p = 0.005) differences were evident with greater MPAG AUC 12 in AAFs and CFs. Conclusion Sex and race differences were evident, with females having slower MPA clearance, higher MPAG AUC 12 , and more severe gastrointestinal AEs. These findings suggest sex and race should be considered during MPA immunosuppression.