Predicting desipramine levels in children and adolescents: A naturalistic clinical study

Objective: To determine the predictability and stability of desipramine (DMI) concentrations in a clinically treated sample of children, estimating the risk of developing potentially toxic DMI levels at a higher dose after a most recent level in a clinically acceptable range. Method: Subjects were 90 consecutive psychiatrically referred children and adolescents treated with DMI with at least two assays of serum DMI concentrations (462 pairs). Assay data were analyzed after log transformation and linear regression. Results: Despite wide between-patient variability in serum DMI levels at the same dose, future within-subject DMI blood levels were highly predictable from knowledge of current levels, current dose, and the future dose. When the DMI serum level was 200 to 300 ng/mL, there was a 7.0% risk for subsequent levels at the same dose to exceed 300 ng/mL, but potentially toxic levels above 500 ng/mL were very infrequent (1.7%). Conclusions: Although the results of this naturalistic clinical study may not generalize to other situations, the results indicate a reasonable stability, predictability, and safety of DMI levels in individual psychiatrically treated children that result from clinically chosen dose changes.