RESUMO
Cyclosporine (CsA) is a component of the first-line treatment for acquired aplastic anemia (acquired AA) in pediatric patients. This study aimed to develop a population pharmacokinetic (PK) model of CsA in Chinese pediatric patients with acquired AA to inform individual dosage regimens. A total of 681 CsA whole blood concentrations and laboratory data of 157 pediatric patients with acquired AA were retrospectively collected from two hospitals in Shanghai. A nonlinear mixed-effect model approach was used to build the population PK model. Potential covariate effects of age, body weight, and biochemical measurements (renal and liver functions) on CsA PK disposition were evaluated. Model fit was assessed using the basic goodness of fit and a visual predictive check. The CsA concentration data were accurately described using a two-compartment disposition model with first-order absorption and elimination. Body weight value was implemented as a fixed allometric function on all clearance and volume of distribution parameters. Total bilirubin level was identified as a significant covariate on apparent clearance (CL/F), with a 1.07% reduction per 1 nmol/L rise in total bilirubin level. The final estimates for CL/F and central volume (Vc/F) were 29.1 L/h and 325 L, respectively, for a typical 28 kg child. Other covariates (e.g., gender, age, albumin, hemoglobin, hematocrit, serum creatinine, and concomitant medication) did not significantly affect the PK properties of CsA. This population PK model, along with a maximum a posteriori Bayesian approach, could estimate individual PK parameters in pediatric patients with acquired AA to conduct individual CsA therapy.
RESUMO
OBJECTIVE: In contrast to severe aplastic anemia (SAA), the appropriate management of patients with moderate aplastic anemia (MAA) is unclear. Recently, it was reported that when childhood MAA was treated with supportive care alone, 2/3 of patients progressed to SAA, and therefore patients with MAA should be treated with immunosuppressive (IS) therapy in time. The present study aimed to review the natural history, the rate of progression to SAA and outcome of children with MAA seen at our institution over the past 12 years and to explore the relationship between the effectiveness of IS therapy and the immune mediated pathological mechanism. METHODS: Seventy-one MAA patients were included in this study. At the first stage, thirty-six children with MAA were given IS therapy (IS group, antithymocyte globulin, ATG or cyclosporin-A, CSA). The therapeutic effects were evaluated and compared with those of 35 children with MAA who received the treatment of supportive care alone (androgens, control group). At the second stage, the patients with MAA progressed to SAA were given combined immunosuppressive (CIS) therapy (CIS group, a combination of ATG, CSA and high-dose immunoglobulin). Peripheral blood lymphocyte subsets levels were measured with a flow cytometer. RESULTS: At the first stage, in the IS group, the percentage of overall and complete responders was 83.3% and 69.4%, respectively, which was significantly higher than that of the control group (34.3% and 17.1%). Twenty-three patients with MAA progressed to SAA. In the control group, 18 patients with MAA progressed to SAA. In the IS group, five patients with MAA progressed to SAA. The 17 patients with MAA who progressed to SAA were given combined immunosuppressive therapy. The percentage of overall and complete responders was 70.6% and 41.2%, respectively. The level of CD4(+), NK cell ratio decreased but the level of CD8(+) cell increased in MAA children before the treatment. The level of NK and CD4(+) cell was significantly higher in the IS group with the treatment than in the control group. CONCLUSION: When childhood MAA is treated with supportive care alone, more than 50% of patients may progress to SAA. Immune mediated pathological mechanism of MAA might be the base of IS therapy. IS therapy is effective and safe for childhood MAA.CIS therapy given to patients with MAA that was progressed to SAA may also be effective.