A drug utilization and drug interaction study in renal transplant patients: Implications for an urgent need for drug deprescribing.

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.