PREDNISOLONE PHARMACOKINETICS IN CHILDREN

Abstract

Clinical observations suggest that some children with chronic diseases respond variably to corticosteroid treatment. 33 children have been studied for bio-availability and metabolism of orally administered prednisone. Physiological doses have been investigated in 5 children with congenital virilizing adrenal hyperplasia; pharmacological doses in 8 patients with dermatomyositis (DMS), 7 with systemic lupus erythematosus (SLE), 9 with childhood nephrosis (N), 2 with regional enteritis, 1 asthmatic and 1 renal transplant patient. Plasma prednisolone values have been determined by a specific radioimnunoassay developed in our lab. Bio-availability was calculated from peak plasma prednisolone levels attained; plasma½ -life values from % disappearance from peak values over hourly time intervals. Results indicate: (1) a regression line may be calculated for dose vs peak levels but there is wide variation among patients in bio-availability; (2) ½-life in children differs from adults (mean 125 minutes vs adult 205 minutes); (3) some children with N and DMS have impaired bio-availability but normal ½-life values; (4) a few children with severe disease (SLE, DMS) have markedly prolonged ½-life values. These studies support observations of clinical variability of drug effects when prednisone is utilized in pharmacolgical doses. Knowledge of bio-availability and metabolism may allow more precise and rational therapeutic programs.