Background and Objectives No evaluation of sex and race influences on MPA pharmacokinetics and adverse effects (AE) during enteric coated mycophenolate sodium (ECMPS) and tacrolimus immunosuppression are available. MPA and MPA glucuronide(MPAG) pharmacokinetics with gastrointestinal AE were investigated in 67 stable renal transplant recipients: 22 African American males(AAM); 13 AA females(AAF); 16 Caucasian males(CM) and 16 Caucasian females(CF) receiving ECMPS and tacrolimus. Methods 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 concentration time curve 0-12 (AUC0-12) and dose normalized AUC 0-12 (AUC*) were determined using a statistical model that incorporated gastrointestinal AE and clinical covariates. Results Males had more rapid apparent MPA clearance (CM: 13.8 ± 6.27 L/h vs. AAM: 10.2 ± 3.73 L/h) compared to females (CF: 8.70 ± 3.33 L/h and AAF: 9.71 ± 3.94 L/hr; 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 AUC0-12 was greater than 60 mg•h/L in 57% of RTR with 71% of patients demonstrating gastrointestinal AE and a higher score noted in females. In all patients, females exhibited 1.40-fold increased gastrointestinal AE scores compared to males (P=0.024). Race (P=0.044) and sex (P=0.005) differences were evident with greater MPAG AUC0-12 in AAF and CF. Conclusion Sex and race differences were evident with females having slower MPA clearance, higher MPAG AUC0-12 and more severe gastrointestinal AE. These findings suggest consideration of sex and race during MPA immunosuppression.

Extrarenal adverse effects (AEs) associated with calcineurin inhibitor (CNI) and mycophenolic acid (MPA) occur frequently but are unpredictable posttransplant complications. AEs may result from intracellular CNI accumulation and low activity of P-glycoprotein, encoded by the ABCB1 gene. Since ABCB1 single nucleotide polymorphisms (SNPs) and sex influence P-glycoprotein, we investigated haplotypes and extrarenal AEs.A prospective, cross-sectional study evaluated 149 patients receiving tacrolimus and enteric coated mycophenolate sodium or cyclosporine and mycophenolate mofetil. Immunosuppressive AE assessment determined individual and composite gastrointestinal, neurologic, aesthetic, and cumulative AEs. Lipids were quantitated after 12-hour fast. ABCB1 SNPs: c.1236C>T (rs1128503), c.2677G>T/A (rs2032582), and c.3435C>T (rs1045642) were determined with haplotype associations computed using the THESIAS program, and evaluated by immunosuppression, sex and race using multivariate general linear models.Tacrolimus patients exhibited more frequent and higher gastrointestinal AE scores compared with cyclosporine with association to CTT (P = 0.018) and sex (P = 0.01). Aesthetic AE score was 3 times greater for cyclosporine with TTC haplotype (P = 0.005). Females had higher gastrointestinal (P = 0.022), aesthetic (P < 0.001), neurologic (P = 0.022), and cumulative AE ratios (P < 0.001). Total cholesterol (TCHOL), low-density lipoproteins (LDL), and triglycerides were higher with cyclosporine. The TTC haplotype had higher TCHOL (P < 0.001) and LDL (P = 0.005). Higher triglyceride (P = 0.034) and lower high-density lipoproteins (P = 0.057) were associated with TTT with sex-adjusted analysis.ABCB1 haplotypes and sex were associated with extrarenal AEs. Using haplotypes, certain female patients manifested more AEs regardless of CNI. Haplotype testing may identify patients with greater susceptibility to AEs and facilitate CNI individualization.