Therapeutic drug monitoring of SSRI's in adolescents

Selective-serotonin-reuptake-inhibitors (SSRI) are found to be effective in the treatment of depression, obsessive compulsive disorder, and anxiety. In this study the serum levels of SSRI were correlated to the therapeutic window suggested by the tiaft (The International Association of Forensic Toxicologists) for adults.Serum levels of the SSRI´s fluvoxamine, citalopram, paroxetine, sertraline, and its metabolite norsertraline, have been studied using HPLC with UV-detection. At doses of citalopram between 10 and 40mg/day serum levels between 8 and 144 ng/ml serum have been found. Most often used was fluvoxamine, with serum levels between 14 and 275 ng/ml serum with doses between 25 and 250mg/day. Especially in the case of fluvoxamine, but also for citalopram, strong interindividual variations of the serum levels, up to tenfold, could be observed, indicating that monitoring of the serum levels is helpful in dose adjustment. In adolescents the serum levels of sertraline and norsertraline are found to be significantly lower as compared to adults. For Paroxetine serum levels seem to be no good indicator for therapeutic response. In summary it seems to be useful to establish therapeutic windows for SSRI´s for adolescents.