Evidence of repeated mirtazapine poisoning in children by hair analysis

Mirtazapine is an antidepressant drug, used to treat depression, but also, in some specific conditions, to treat obsessive-compulsive disorder and anxiety. Although mirtazapine is not a hypnotic, it can make the subject feel drowsy. Children under the age of 18 should not take mirtazapine, but for some very special diseases, a physician can prescribe it for a limited period of time. The authors report a case involving 2 children (7- and 9-year-old) who were administered mirtazapine without consent by the mother, who was under daily therapy with this antidepressant. Hair specimens, collected from the children were tested by liquid chromatography coupled to tandem mass spectrometry for mirtazapine and its metabolite, N-desmethylmirtazapine, on 3 x 1 cm segments. The hair test results (3 x 1 cm segments) have demonstrated that both children have been repetitively exposed to mirtazapine for approximately the last 3 months before hair collection, with concentrations in the range 1.32-3.79 and 0.64-2.54 ng/mg for mirtazapine and N-desmethylmirtazapine, respectively. Environmental contamination was ruled out as the measured concentrations are highly variable according to the pattern of drug distribution and the washes were negative. Hair testing for drugs appears as an excellent diagnostic tool for child protection toward drug exposure.