Background and importance Pharmacokinetic monitoring of the transplanted patient is essential to keep blood concentrations of immunosuppressive drugs in range, and to reduce the risk of organ rejection and the adverse effects associated with these drugs.

Aim and objectives To assess the degree of acceptance by the nephrology service of recommendations made by the clinical pharmacokinetics unit after monitoring everolimus blood concentrations at a third level general university hospital.

Material and methods This was a retrospective observational study in renal transplant patients with at least two everolimus determinations between January 2016 and September 2019. Patients were identified from the Gestlab programme and data collected were: age, sex, date of testing, concomitant immunosuppressive treatment, blood concentrations and pharmacokinetic recommendations. The number of blood determinations per patient, percentage of pharmacokinetic recommendations accepted by the physician and the proportion of values lower and higher than the established therapeutic range were evaluated; the target therapeutic interval for monotherapy is 6–10 ng/mL and in combination with calcineurin inhibitors is 3–8 ng/mL.

Results Pharmacokinetic monitoring was performed in 49 patients, 59% men, with an average age of 60±12 years and an average of 9±5.3 everolimus determinations. In 65.3% of patients, treatment was with everolimus and tacrolimus simultaneously. A total of 443 samples were analysed, with a dose adjustment required in 34.7%. The average everolimus percentages lower and higher than the target range were 23% and 11.3%, respectively. The dosing recommendations of these patients were accepted in 69% of cases. After this adjustment, 66.1% of patients tested showed drug concentrations in range. Of the total recommendations not accepted, 31% of medical actions differed from the recommendation in the prescribed final dosing regimen.

Conclusion and relevance During the study period, posology individualisation was necessary in almost 35% of the analyses performed by the clinical pharmacokinetics service, with the pharmacokinetic recommendations accepted by the prescriber in more than 60% of cases.

References and/or acknowledgements No conflict of interest.