Introduction: Sirolimus (Rapamune) is an important immunosuppressive drug in kidney transplant patients. The usual maintenance dose of Sirolimus in these patients is 2 to 5 mg/d and its optimal maintenance trough level is 5 to 10 ng/mL. The required Sirolimus doses may differ markedly from patient to patient. It is because of high inter and intrapatient variability in its pharmacokinetics. There have been no studies in Iran on the correlation of Sirolimus blood level and its target dose. This study has been done to show the target dose of Sirolimus in kidney transplanted patients in Isfahan.
Methods: This is a longitudinal cross-sectional study conducted from June 2018 to September 2019. The study population included all kidney transplanted patients treated with Sirolimus in a nephrology private clinic. Inclusion criteria were age (equal or more than 18 years old) and the existence of complete data in the patient's file. The participants were excluded if there were not at least two Sirolimus levels in the patient's file. Demographics and other variables were extracted from the patient's files.
Results: Sirolimus was prescribed for seventy-three patients. Sixteen patients did not have the inclusion criteria. Fifty-seven renal transplanted patients were included in the study. The mean starting dose of Sirolimus in these patients was 2 ± 0.19 mg/d. The mean of the Sirolimus dose was 1.2 ± 0.44 mg/d. There was more than 20% GFR improvement in 68% of the patients after changing the Calcineurin Inhibitor to Sirolimus (P < .05).
Conclusion: In a significant number of patients changing CNI to Sirolimus accompanied by GFR improvement. Contrary to the recommended dose of Sirolimus in the references (2 to 5 mg/d) Iranian kidney transplant recipients needed lower daily doses of Sirolimus (1.2 mg/d) to achieve the desired whole blood level. Further studies are recommended to confirm it.