An LC-MS/MS method for the simultaneous determination of 15 antipsychotics and two metabolites in hair and its application to rat hair

- A LC-MS/MS method for the detection of 15 antipsychotics in hair was developed.
- This method was validated and successfully applied to the analysis of rat hair.
- The effect of pigmentation on the deposition of 3 antipsychotics was investigated.
- This method will be useful for monitoring the inappropriate use of antipsychotics.

In recent years, the inappropriate use of antipsychotics by young Korean men has become a social problem. As military service exemptions are given for mental illness, some men pose as mental health patients to avoid military service. In order to verify the authenticity of mental illnesses, we developed simultaneous analytical methods for the detection of 15 antipsychotics and 2 of their metabolites in hair using liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The target drugs were modafinil, atomoxetine, aripiprazole, benztropine, buspirone, duloxetine, gabapentin, oxcarbazepine, topiramate, escitalopram, paliperidone, ziprasidone, lamotrigine, clonazepam, levetiracetam, and metabolites of oxcarbazepine and clonazepam. To remove possible contaminants on the hair surface, hair samples were washed twice with methanol and distilled water, and then were extracted with methanol overnight at 38 °C. Desipramine-d3 was used as an internal standard. LC-MS/MS analysis was performed on an Agilent 1290 Infinity UHPLC coupled to an AB Sciex Qtrap® 5500 MS/MS. The total chromatographic run time was 14 min. The following validation parameters were evaluated: selectivity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, matrix effect, and recovery. The LOD and LOQ values for all analytes, except modafinil, ranged from 0.2 to 10 pg/mg hair and from 0.2 to 20 pg/mg hair, respectively. Good linearity was achieved for most of the analytes in the range of 20-200 pg/mg hair. The method showed acceptable precision and accuracy, which were less than 15%, as well as satisfactory matrix effects and recoveries. Furthermore, this method was also applied to the analysis of rat hair samples. The study in rats showed that the concentrations of atomoxetine and aripiprazole in pigmented hair were significantly higher than those in non-pigmented hair. However, no significant difference was observed in the concentration of topiramate between pigmented and non-pigmented hair. This method will be useful in monitoring the inappropriate use of antipsychotics in suspects posing as mental health patients. However, further research is necessary before applying this method to authentic hair samples from mental health patients.