Plasma levels of imipramine and metabolites in 68 hospitalized children.

Steady-state plasma imipramine levels were measured in 68 hospitalized children. Interindividual variability (imipramine 12-fold; desipramine 72-fold; 2 hydroxyimipramine 33-fold; 2 hydroxydesipramine 3-fold) was not correlated with clinical or demographic variables. However, intraindividual levels were reproducible and were linearly correlated with dose (r = 0.76; p less than 0.005). Clinicians, by using plasma level monitoring, can rationally adjust dosages so that all patients will be in the optimum range, ensuring an adequate trial while avoiding supratherapeutic levels associated with cognitive toxicity.