Losartan is used for anti-proteinuric as well as blood pressure effects in chronic kidney disease (CKD). It is metabolized by cytochrome P450 2C9 to active E-3174. Single nucleotide polymorphisms in CYP2C9 that reduce catalytic activity could reduce clinical benefits. The study aims were to determine whether CYP2C9 variant alleles (*2 and *3) altered urinary protein excretion, glomerular filtration rate, and blood pressure in Caucasians prescribed losartan. Differences between baseline and six-month follow-up outcomes were compared by CYP2C9 genotypes in 59 patients using unpaired T-test or Mann Whitney U test. Primary renal disease patients had a trend toward less favorable antiproteinuric response (−31.7±156 vs −125±323%; p=0.123) when carrying variant alleles. Patients with secondary renal diseases had less favorable diastolic blood pressure (9.8±16.0 mm Hg vs −3.2±10.6 mm Hg; p=0.043) and systolic blood pressure (16.2±27.1 mm Hg vs −5.5±17.5 mm Hg; p=0.044) with CYP2C9 variants. Preliminary results suggest a possible influence of CYP2C9 genotype on proteinuria and blood pressure in Caucasian CKD patients treated with losartan.

Purpose The role of pharmacogenomics, clinical and demographic parameters in pharmacokinetic predictions was evaluated in patients receiving mycophenolic acid (MPA). Methods A cohort study design of patients with glomerulonephritis secondary to lupus nephritis and anti-neutrophil cytoplasmic antibody (ANCA) vasculitis was employed. Forty-six patients with lupus nephritis and ANCA vasculitis who were receiving MPA were recruited from the nephrology clinic. The study assessed the relative single and combined roles of genomic, clinical, and demographic characteristics on pharmacokinetic parameters using general linear models. The study focused on polymorphisms in UGT1A7, UGT2B7, and ABCB1/MDR1; all of which have limited data available concerning MPA pharmacokinetics. All patients had pharmacokinetic assessments for MPA and glucuronide metabolites (MPAG, AcMPAG). Genotyping was performed for known variants of UGTs (UGT1A9, UGT1A7, UGT2B7), and multidrug resistance protein (ABCB1/MDR1), involved in MPA disposition. Analyses included univariate and multivariate linear modeling. Results In univariate analyses, UGT2B7 heterozygosity (coefficient 0.3508; R2=0.0873) and UGT1A7 heterozygosity (coefficient 0.3778; R2=0.0966) predicted increased apparent oral clearance of MPA. UGT1A7 heterozygosity (coefficient −0.4647; R2 0.0897) predicted lower MPA trough concentrations. In multivariate assessments, higher urinary protein excretion, lower serum creatinine, and increased weight predicted greater apparent oral clearance of MPA (p< 0.0001). White race and higher serum creatinine predicted higher MPA trough concentrations (p<0.0001). Higher exposure to MPA was predicted by decreased urinary protein excretion and increased serum creatinine. Conclusions Clinical and demographic parameters were 2–4 times more important in MPA disposition than genotypes and explained 30–40% of the pharmacokinetic parameters.

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