Cytochrome P450 (CYP) enzymes, such as CYP3A4, and CYP3A5, P450 oxidoreductase (POR), peroxisome proliferator activated receptor alpha (PPAR-alpha), and drug transporter (ABCB1) were observed to influence concentrations of immunosuppressants (cyclosporine, everolimus, sirolimus, and tacrolimus) and outcomes in renal transplants. We carried out the present study to evaluate the prevalence and impact of these single nucleotide polymorphisms (SNPs) in adult renal transplants. SNPs were evaluated using commercial TaqMan® assays. Serum drug concentrations were estimated using immunoassays. One hundred and forty-six patients were recruited. SNPs in CYP3A5*3 were significantly associated with greater dose-adjusted cyclosporine and tacrolimus concentrations. SNPs in POR*28 were observed with significantly lower dose-adjusted concentrations, particularly with cyclosporine and tacrolimus. ABCB1 homozygous polymorphisms were observed with significantly lower time spent in the therapeutic range with cyclosporine and everolimus/sirolimus. Cyclosporine was observed in a significantly greater proportion of patients with elevated GGT, and SNPs in PPAR-alpha were significantly associated with an increased risk of this adverse event. Hypertriglyceridemia with everolimus was significantly associated with POR*28 polymorphisms. There is a need to validate the influence of these SNPs in a prospective study and develop an algorithm predicting the achievement of target concentrations.

BACKGROUND: Renal transplant patients receive several drugs concomitantly. OBJECTIVE: Limited literature exists evaluating the drug use in this population that is at high risk for drug-induced acute kidney injury and complications due to under-or over-dosage of immunosuppressant drugs due to drug–drug interactions. METHODS: A retrospective observational study was carried out in 269 renal transplant patients in whom either oral or parenteral drugs were evaluated. World Health Organization (WHO) indicators of drug utilization such as the average number of drugs prescribed, daily defined dose, and proportion of drugs listed as WHO essential drugs were evaluated. Details on the drugs with nephrotoxic potential were obtained. Drug–drug interactions were assessed concerning the severity (major, moderate, and minor) as well as type (pharmacokinetic, pharmacodynamic, and toxicity). RESULTS: One-hundred and ninety-eight drugs were administered to the study participants. The median (range) total number of drugs received by the study participants was 23 (6–55). The proportion of drugs listed in the WHO essential drug database was 57.1 (16.7–100)%. Forty-six drugs with potential nephrotoxicity and seven drugs that were contra-indicated in patients with chronic renal disease/end-stage renal disease were administered to the study participants. The mean (SD) numbers of drug interactions observed amongst the study participants were 18.4 (10.1). Age (β: 0.2, 95% CI: 0.1, 0.3) and duration of renal transplantation (β: −0.3, 95% CI: −0.5, −0.1) were the significant predictors of drug burden. A total of 645 drug interactions were identified amongst the study participants (major – 240; moderate – 270; and minor – 135) of which the majority were pharmacokinetic followed by toxicity risk. Age was significantly associated with the risk of potential drug interaction (OR: 2.6, 95% CI: 1.8, 12.4; p = 0.001). CONCLUSION: Drug treatment in renal transplant patients poses a significant burden in terms of nephrotoxicity potential and drug–drug interactions. A dedicated ambulatory clinical pharmacy service monitoring the drug use coupled with drug deprescribing strategies are the need of the hour in this population.

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