ORIGINAL ARTICLE Conversion from Prograf to Advagraf in stable paediatric renal transplant patients and 1-year follow-up Antonio J. Carcas-Sansuán & Laura Espinosa-Román & Gonzalo N. Almeida-Paulo & Angel Alonso-Melgar & Carmen García-Meseguer & Carlota Fernández-Camblor & Nicolás Medrano & Elena Ramirez Received: 14 May 2013 / Revised: 26 June 2013 / Accepted: 26 June 2013 # IPNA 2013 Abstract Background The conversion from Prograf to Advagraf on a 1:1 (mg:mg) basis has been questioned in light of the publi- cation of studies showing a decrease in tacrolimus blood concentrations after the administration of Advagraf. Methods The bioavailability of Prograf and Advagraf was evaluated in an open-label conversion study in 21 stable renal transplant paediatric patients. Serial blood samples for determining tacrolimus levels were collected during a 24-h period before (on Prograf) and after (on Advagraf) conversion. Tacrolimus pharmacokinetic parameters were calculated using a non-compartmental approach and the relative bioavailability calculated. Clinical and analytical data were obtained at 30, 90, 180 and 360 days after study enrolment. Results The mean ratio and 90 % confidence interval (CI) for peak plasma drug concentration (C max ) and the area under the time–concentration curve during the first 24 h (AUC 0–24 ) were 81.54 (95 % CI 71.6–92.87) and 87.19 (95 % CI 79.91–95.13), respectively. Renal glomerular filtration rate remained stable over the course of the follow-up. Two patients presented clinical events unrelated to tacrolimus. Tacrolimus levels decreased in the first month, the dose/level ratio in- creased between months 1 and 6 and slight dose adjustments were required during the follow-up period. Conclusions Our results show that Advagraf bioequivalence cannot be ensured in this population. Significant changes in tacrolimus levels and dose were observed on long-term follow-up. Keywords Bioavailability . Children . Concentrations . Pharmacokinetics . Tacrolimus Introduction Immunosuppression is required in all types of transplants to prevent graft failure and graft loss. Treatment compliance in immunosuppression is required and must be ensured because nonadherence is potentially a major risk factor for graft failure [1, 2]. Studies have shown that patients who have undergone renal transplantation are more susceptible to med- ication nonadherence, which may be due to the non-vital nature of the kidneys [3, 4]. Trial registry: EudraCT no. 2009-017600-89. A. J. Carcas-Sansuán (*) : N. Medrano : E. Ramirez Clinical Pharmacology Service, University Hospital La Paz, Paseo de la Castellana, 261, 28046 Madrid, Spain e-mail: antonio.carcas@uam.es N. Medrano e-mail: micomedrano@live.com E. Ramirez e-mail: relicena@gmail.com A. J. Carcas-Sansuán : G. N. Almeida-Paulo : N. Medrano : E. Ramirez Department of Pharmacology, School of Medicine, Autonomous University of Madrid, Madrid, Spain G. N. Almeida-Paulo e-mail: gnapaulo@usal.es L. Espinosa-Román : A. Alonso-Melgar : C. García-Meseguer : C. Fernández-Camblor Department of Paediatric Nephology, Children’ s Hospital La Paz, Madrid, Spain L. Espinosa-Román e-mail: lespinosar@salud.madrid.org A. Alonso-Melgar e-mail: aamelgar@salud.madrid.org C. García-Meseguer e-mail: cgmeseguer@salud.madrid.org C. Fernández-Camblor e-mail: carlotam.fernandez@salud.madrid.org Pediatr Nephrol DOI 10.1007/s00467-013-2564-y