Background: Previous studies have postulated that four structural compartments may be differentiated in hair: surface protein domain, water-accessible protein domain, water-inaccessible protein domain, and melanin. Drugs contained in blood, sweat, sebum, and environment would be deposited in the first two domains, with primarily drugs in blood being incorporated in the latter two domains during hair synthesis. Drugs in the first two domains would be removed by washing procedures. Use of enzymatic extraction procedures and evaluation of hair for damage from harsh cosmetic treatments might help to separately identify and quantify the drugs incorporated in the second two domains.
Aims: a) Development of an UPLC-MS/MS method for the simultaneous quantification of the following 19 antipsychotic drugs and metabolites in hair: amisulpride, aripiprazole, chlorpromazine, clotiapine, clozapine, desmethylclozapine, desmethylolanzapine, haloperidol, norchlorpromazine, 7-OH-quetiapine, 9-OH-risperidone, olanzapine, pimozine, pimpamperone, quetiapine, risperidone, sertindole, sulpride, and tiapride; b) evaluation of measurement of patient adherence to prescribed medication use, c) determination of the influence of biochemical individuality effects on hair drug content, d) evaluation of relative binding of antipsychotic drugs to protein and to melanin hair structures.
Method: Approximately 10 mg of intact hair were decontaminated with isopropanol and phosphate buffer, and then enzymatically digested overnight with dithiothreitol. After centrifugation, the supernatant digest (protein fraction) was separated from the remaining melanin hair pellet (melanin fraction). Melanin fraction was washed with water, and the drugs were extracted with dimethyl sulfoxide with ball-mill pulverization. Both fractions were purified with solid-phase cation exchange cartridges and injected in the UHPLC-MS/MS system.
Results and discussion: Validation of the method was carried out on the protein fraction following international guidelines. The limits of quantification ranged from 1.6-40 pg/mg. The method was applied to 59 head hair samples from prisoners from an antipsychotic compliance study in the criminal justice system in US. The patients were under chlorpromazine, haloperidol, risperidone, olanzapine, or quetiapine multiple antipsychotic treatment, during incarceration. The first head hair centimeter, closest to the scalp, was analyzed. The results were evaluated in relation to the type of hair, colour, hair damage, drug melanin affinity, and prescribed dose. In general, no good correlation between the prescribed dose/concentration in hair was obtained. A wide range of antipsychotic concentrations were observed 'dose mg/day (d); pg/mg protein fraction (A)': chlorpromazine (d:50-400;A:<LOQ->1600) and its metabolite norchlorpromazine (A: <LOQ->1600), haloperidol (d:4-20;A: <LOQ-2902), olanzapine (d:5-20;A: <LOQ-223) and its metabolite desmethylolanzapine (A: <LOQ -136), quetiapine (d:4-400;A: <LOQ -2754) and its metabolite 7-OH-quetiapine (A: <LOQ -1448), risperidone (d:2-20;A: <LOQ->1600) and its metabolite 9-OH-quetiapine (A:<LOQ-296;B). Melanin was found to have a 2- to 85-fold higher drug-binding affinity relative to the protein fraction CONCLUSION: This report describes a different viewpoint method of quantifying the antipsychotics in the melanin and water-inaccessible protein fraction of hair, separately. No correlation between the prescribed dose and the concentrations found in the protein and melanin domains were observed. The results show that hair melanin would have a much higher affinity for the antipsychotic medications than do hair proteins, being influenced mainly by biochemical individuality effects and less by hair colour. Future studies would be of interest using the proposed extraction method applied to hair of different colours.
Keywords: Antipsychotics; Chlorpromazine; Hair; Haloperidol; Melanin; Olanzapine; Protein; Quetiapine; Risperidone; UPLC–MS/MS.
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