Conversion from Prograf to Advagraf in stable paediatric renal transplant patients and 1-year follow-up

Background The conversion from Prograf to Advagraf on a 1:1 (mg:mg) basis has been questioned in light of the publication 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 increased 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.