Therapeutic drug monitoring of olanzapine in children and adolescents with anorexia nervosa: A pilot study

Aims: Olanzapine was previously used in adolescents diagnosed with Anorexia Nervosa (AN). First results concerning weight gain, reduced anxiety, improvement of distorted body schemes and obsessive-compulsive symptoms had been achieved. The aim of this pilot study was the evaluation of the treatment in adolescents with AN using therapeutic drug monitoring. Methods: 16 adolescent females (11–17 years) with AN received olanzapine over five weeks with a starting dose of 5mg, dose was increased after 1 week to 10mg. Clinical symptoms were captured using the scales as provided by the database of the “TDMKJP e.v.” network. (EDE Interview, EDI-2, Y-BOCS, CDRS, PANSS, PAERS, GAF). Plasma levels were measured twice after three and five weeks. Results: Plasma levels varied from 0–69ng/ml (mean 33) on the first assessment, from 0–65ng/ml (mean 36) on the second. The EDE-Restraint showed a reduction from 20 (range 0–30) to 14, the GAF an increase from 42 (5–68) to 52 (31–75). The BMI increased from 14.84 (12.06–17.82) to 16.67 (13.50–19.98). No significant changes in obsessive-compulsive symptoms could be measured. Main adverse event was tiredness/sleepiness. Conclusion: In this sample, it could be shown that olanzapine is both, well tolerated and partially effective. Due to the small sample size, clinical significance of the results is limited. Regarding the variation of the plasma levels of olanzapine, TDM is a useful and important tool to control over- and underdosage. To strengthen the significance of the findings and to identify factors that may influence the plasma levels, further studies with larger sample sizes are urgently needed.