A RETROSPECTIVE STUDY OF SERUM LEVELS AND ELECTROCARDIOGRAPHIC EFFECTS OF NORTRIPTYLINE IN CHILDREN AND ADOLESCENTS

Objective: We retrospectively evaluated a large pediatric population treated with nortriptyline (NT) in an outpatient psychopharmacology clinic to assess pharmacokinetic and electrocardiographic (EKG) effects. Methods: A systematic search revealed 82 children and adolescents treated naturalistically with NT. All patients with available EKGs and serum NT levels were included in the series with the exception of those receiving concomitant antipsychotic agents. Forty-three percent of subjects were receiving medications in addition to NT. Results: Patients received an average (+/-SE) NT dose of 2.0 +/- 0.1 mg/kg yielding mean serum NT levels of 105.5 +/- 7.4 ng/mL. There was a linear relationship of NT dose (mg/kg) to serum NT levels (r = 0.50, p < 0.0001). NT treatment resulted in small increases in heart rate, and PR, QRS, and QTc intervals (all ps < 0.01), of similar magnitude in children and adolescents. Individuals with the highest baseline EKG indices had the least amount of change in those indices with NT treatment. There were only a few statistically significant associations between NT dose or serum NT levels and EKG parameters. NT treatment was significantly associated with the onset of asymptomatic sinus tachycardia (heart rate > 100 beats per minute), and prolongation of the EKG QRS (> 100 msec) and QTc (> 440 msec) intervals. Conclusions: These findings suggest: (1) NT has a predictable dose to level relationship, (2) the effect of NT on the EKG in this age group is mild and similar to that reported with other tricyclic antidepressants, and (3) there are few age-specific differences in NT-induced EKG changes.