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01-01-2001 | Original Research Article

Covariate Effects on the Apparent Clearance of Tacrolimus in Paediatric Liver Transplant Patients Undergoing Conversion Therapy

Authors: Dr María Jose García Sánchez, Cecilia Manzanares, Dolores Santos-Buelga, Alberto Blázquez, Javier Manzanares, Pedro Urruzuno, Enrique Medina

Published in: Clinical Pharmacokinetics | Issue 1/2001

Abstract

Objective

To analyse the influence of covariates on the apparent clearance (CL) of tacrolimus in paediatric liver transplant recipients being converted from cyclosporin to tacrolimus.

Design

Retrospective modelling study.

Patients and participants

18 children, 13 girls and 5 boys, aged 4 months to 16 years (median 9.1 years) who required conversion to tacrolimus because of acute or chronic rejection or cyclosporin toxicity.

Methods

287 whole-blood tacrolimus concentrations from therapeutic drug monitoring were used to build a nonlinear mixed-effects population model (NON-MEM program) for the apparent clearance of tacrolimus. Variables considered were age, total bodyweight (TBW), body surface area (BSA), time after initiation of treatment (T), gender, haematocrit (Hct), albumin (Alb), aspartate aminotransferase (AST), alanine aminotransferase (ALT), γ-glutamyl transpeptidase (γGT), alkaline Phosphatase (ALP), bilirubin (BIL), Creatinine clearance (CL_cr) and dosage of concomitant corticosteroids (EST).

Results

TBW, T, BIL and ALT were the covariates that displayed a significant influence on CL according to the final regression model: CL (L/h) = 10.4(TBW/70)¾ · e-000032 T· e-0.057 BIL. (1- 0.079 ALT). With this model, the estimates of the coefficients of variation were 24.3% and 29.5% for interpatient variability in CL and residual variability, respectively.

Conclusions

The proposed model for tacrolimus CL can be applied for a priori dosage calculations, although the results should be used with caution because of the unexplained variability in the CL. We therefore recommended close monitoring of tacrolimus whole blood concentrations, especially within the first months of treatment. The best use of the model would be its application in dosage adjustment based on therapeutic drug monitoring and the Bayesian approach.

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Title: Covariate Effects on the Apparent Clearance of Tacrolimus in Paediatric Liver Transplant Patients Undergoing Conversion Therapy
Authors: Dr María Jose García Sánchez
Cecilia Manzanares
Dolores Santos-Buelga
Alberto Blázquez
Javier Manzanares
Pedro Urruzuno
Enrique Medina
Publication date: 01-01-2001
Publisher: Springer International Publishing
Published in: Clinical Pharmacokinetics / Issue 1/2001
Print ISSN: 0312-5963
Electronic ISSN: 1179-1926
DOI: https://doi.org/10.2165/00003088-200140010-00005

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Springer Medicine

Covariate Effects on the Apparent Clearance of Tacrolimus in Paediatric Liver Transplant Patients Undergoing Conversion Therapy

Abstract

Objective

Design

Patients and participants

Methods

Results

Conclusions

Keynote webinar | Spotlight on medication adherence

Springer Medicine

Abstract

Objective

Design

Patients and participants

Methods

Results

Conclusions

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