Abstract

Hair and nails are keratinized matrices that can be used in Toxicology as matrices for the long-term detection of substances. Whereas hair is an established matrix with decades of use in this field, nails have been less studied, especially including a comparison to hair samples. Specifically in the case of antidepressant and benzodiazepine drugs, very few publications analyzing these drugs in nail samples exist as of yet. For this reason, in the present study a method for the detection of 12 antidepressant and benzodiazepine drugs in hair and nail samples was developed. Samples were decontaminated with 3 washes of dichloromethane, and 25 or 30 mg of hair and nails, respectively, were pulverized. Then, the samples were incubated with 1.5 mL water:ACN (50:50, v/v) with horizontal agitation for 90 min. The supernatant was evaporated and reconstituted in 200 µL of methanol and 2 mL of 2% FA in water, submitted to solid phase extraction (SPE) using Oasis MCX cartridges and analyzed by LC-MS/MS. The method was satisfactorily validated in nail and hair samples for the following parameters: linearity, LOD (0.005–0.02 ng/mg), LOQ (0.01–0.02 ng/mg), selectivity, carryover, accuracy, imprecision, matrix effect, extraction efficiency, process efficiency and autosampler stability. Matched fingernail, toenail and hair samples were obtained from 21 patients under treatment with any of the studied drugs and analyzed with the developed method. The most frequently detected drugs were venlafaxine (n = 11), trazodone (n = 6), zolpidem (n = 5), alprazolam (n = 5) and nordiazepam (n = 5). Concentrations in hair, fingernails and toenails, respectively, were 44.31 ng/mg, 8.05–43.35 ng/mg and 7.02–22.69 ng/mg for venlafaxine; 5.40–19.08 ng/mg, 0.13–1.00 ng/mg and 0.42–1.04 ng/mg for trazodone; 13.86 ng/mg, 5.19 ng/mg and 9.11 ng/mg for fluoxetine; 7.42 ng/mg, 1.85 ng/mg and 0.03–2.81 ng/mg for sertraline; 0.40–1.42 ng/mg, 0.12 ng/mg and 0.16 ng/mg for zolpidem; and 0.02–0.11 ng/mg, 0.07–1.07 ng/mg and 0.05 ng/mg for alprazolam for the patients under active treatment. Hair concentrations were higher than nail concentrations for most drugs in patients under active treatment, with the exception of diazepam (n = 1; 0.12 ng/mg in hair and 0.41 ng/mg in fingernails). Fingernail concentrations were lower than toenail concentrations in patients under active treatment in most compared cases. Comparison of fingernails and toenails of a patient with antifungal treatment did not show an observable effect in concentrations.

Highlights

  • Hair and nails are keratinized matrices known to incorporate substances present in the blood, and store them for a long time, allowing for a retrospective determination of drug consumption

  • Segmentation was performed for hair when possible but not in nails because of the difficulty to segment nail clippings

  • Drug distribution in paired samples was studied, detecting higher concentrations in hair than in nails in most cases, probably due to these drugs binding to hair melanin

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Summary

Introduction

Hair and nails are keratinized matrices known to incorporate substances present in the blood, and store them for a long time, allowing for a retrospective determination of drug consumption. Nail analysis has been used to determine exposure to different toxic metal ions [17,18], and more recently, nail samples have been proposed as an alternative to hair analysis for drugs of abuse [19]. Since both are keratinized matrices, they share common characteristics, but differ in some aspects. Nails lack a cuticle layer, making them more susceptible to external contamination and unwanted extraction of the analytes during washing, and under normal circumstances, nails do not contain melanin, eliminating the bias due to pigmentation [21]

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