Mycophenolate mofetil (MMF) is given to children in fixed doses based either on body weight or body surface area. There are data indicating mycophenolic acid (MPA) blood levels should be monitored in the early period of transplantation. However, there is little information regarding MPA pharmacokinetics (PK) in stable pediatric recipients. We evaluated MPA-PK in 20 stable renal transplant children (11.7±1.9 years) under long-term (46±31 months) MMF (26.1±7 mg/kg per day or 785±183 mg/m 2 per day) therapy plus prednisone and cyclosporin A (n=16), tacrolimus (n=3), or MMF/prednisone (n=1). Total MPA levels were measured using the EMIT-MPA assay at 0, 1, 2, 3, 4, 6, and 8 h after an oral dose of MMF. The level at 12 h was considered equal to the trough level for AUC 0-12 calculation. Mean C 0 , C max , AUC 0-12 , and T max were 3.46±1.32, 13.5±0.58 µg/ml, 63.2±24.4 µg.h/ml, and 1.3±0.6 h, respectively. Six (30%) children were considered to have an adequate exposure (36-54 µg.h/ml) to MPA, 11 (55%) showed an AUC 0-12 >54 µg.h/ml, and 3 (15%) showed an AUC 0-12 <36 µg.h/ml. A C max ≥10 µg/ml was seen in 13 (65%) children. MMF dose did not correlate with AUC 0-12 or C max . The combination of variables C 0 , C 1 , and C 4 provided an equation to predict exposure (r 2 =0.75) where AUC 0-12 =12.62+ (7.78xC 0 )+(0.90xC 1 )+(1.30xC 2 ) (P<0.001). The use of MMF without monitoring MPA blood levels may cause unnecessary overexposure to the drug in stable pediatric recipients.

The use of MMF without monitoring MPA blood levels may cause over-/underexposure to the drug in stable recipients. However, in patients under MMF for more than 1 yr, MPA levels are stable and there is no need for frequent measurements.

These data indicate that PPI decreases the MPA exposure when associated with both CNIs but particularly in the first week after RTx. In this period, the MMF dose should be increased. This effect lasts throughout the first year but does not seem to be clinically relevant after the first week.

Introdução:A cistatina C sérica tem sido apontada como um marcador de filtração glomerular. Objetivo: Realizar a validação de um método específico e automatizado, a imunonefelometria, mensurando os níveis séricos de cistatina C por meio do nefelômetro da empresa Behring (BN II) e correlacionar resultados obtidos entre pacientes transplantados. O ensaio perfaz o intervalo de referência de 0,23-7,25 mg/l. A imprecisão intra e interensaio foi de 8,73% e 5,38%, respectivamente. A recuperação analítica da cistatina C após adição de controle foi entre 86,7 % e 98% (média 92,3%). A estabilidade da cistatina C à temperatura ambiente, sob refrigeração e sob congelamento foi testada. A perda mais significativa foi encontrada nas amostras armazenadas à temperatura ambiente, em que foram perdidos até 10% da concentração inicial. Foi encontrado coeficiente de variação de 14,79% para sensibilidade analítica. Durante todo o processo foram comparados os resultados com o controle de qualidade e obtivemos bons resultados. Depois desses testes, nós comparamos as correlações em três grupos de pacientes transplantados renais sob diferentes esquemas de imunossupressão (n = 197) -azatioprina (n = 36), micofenolato mofetil (n = 131) e sirolimus (n = 30) -entre as equações de estimativa de filtração glomerular (Cockroft Gault, Nankivell e Modification of Diet in Renal Disease) e cistatina C sérica ou creatinina sérica. Conclusão: O ensaio nefelométrico cistatina C pode perfeitamente ser adequado à nossa rotina laboratorial e as correlações entre creatinina sérica e as diferentes equações de estimativa de filtração glomerular são melhores do que quando comparamos as mesmas à cistatina C nos três grupos, independentemente da terapia imunossupressora utilizada. resumo unitermos Cistatina Nefelometria Função renal Transplante Imunossupressores abstractIntroduction: Serum cystatin C has been identified as a glomerular filtration marker. Objective: To validate immunonephelometry, a specific and automated method, by measuring levels of serum cystatin C through Behring nephelometer (BN II) and correlate results among transplant patients. The assay comprises the reference range of 0:23 to 7:25 mg/l. The intra-assay and inter-assay imprecision rates were 8.73% and 5.38%, respectively. The analytical recovery of cystatin C after addition of control was between 86.7% and 98% (average 92.3%). The stability of cystatin C to room temperature, refrigerated or frozen was tested. The most significant loss was found in samples stored at room temperature, in which up to 10% of the initial concentration was lost. The coefficient of variation was 14.79% for analytical sensitivity. Throughout the process the results were compared with quality control and good results were achieved. After these tests, we compared the correlations between equations for estimating glomerular filtration rate (Cockroft Gault, Nankivell and MDRD) and serum cystatin C or serum creatinine in three groups of kidney transplant patients under different immunosuppressive regimens (n = 197...

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