Cyclosporine level at the second hour in pediatric hematopoietic stem cell transplant patients.

In this retrospective study, cyclosporine levels at the second hour (C2 levels) were measured during oral cyclosporine intake in 28 pediatric hematopoietic stem cell transplant patients, and the relations between cyclosporine dosage and C0, C2 levels, C2/C0 ratio, and cyclosporine-related adverse effects were investigated. Cyclosporine levels at the second hour levels were found to be significantly lower in children younger than 7 years old, suggesting age-related differences in absorption and metabolism of the drug. There were statistically significant correlations of both C0 and C2 levels with blood creatinine values. In addition, a statistically significant negative relation was found between C0 and C2 levels and serum potassium levels; this unexpected finding was attributed to multiple drug effects in the early posttransplant period. The common adverse effects of cyclosporine (gingival overgrowth, gynecomastia, and hypertrichosis) were also evaluated in this study, and no correlation was found between those adverse effects and C0, C2 levels, C2/C0 ratio, and cyclosporine dosage. In the present study, despite the highly significant correlation of C2 levels with renal and metabolic effects, in pediatric hematopoietic stem cell transplant patients, measurement of C2 levels as a standard practice did not provide an advantage over C0 monitoring. However, the preliminary results suggest that C2 level monitoring could be useful in selected patients with increased risk of renal toxicity or in states where a better estimation of gastrointestinal absorption is needed.