Interpretation of hair findings in children: about a case involving carbamazepine

Evidence of exposure to flecainide in a newborn by keratinous matrices testing and interpretation of the findings

Pediatric poisoning represents a serious problem all around the world. Abuse or neglect of children by adults must be highlighted in children exposed to drugs to which they would not normally have access. Usually, segmental hair analysis would allow in these contexts to determine whether the exposure was unique or repetitive. Hair and nail samples from a 9-month-old girl were received in our laboratory for analysis, after the child was hospitalized due to severe dehydration caused by her mother's neglect. At the admission, flecainide, an antiarrhythmic never prescribed to the child, was identified in the daughter urine. Using an LC-MS/MS method, flecainide tested positive in the child's hair at the following concentrations: 66 pg/mg (root to 1 cm), 61 pg/mg (1-2 cm), and 125 pg/mg (2-3 cm). Traces below the limit of quantification (1 pg/mg) were also present in the nail clippings. These concentrations are much lower than those obtained in adults under daily treatment. Given the different pharmacokinetic and dynamic parameters in children, the different rate of hair growth, and the greater porosity of the hair, which makes it more prone to external contamination, the interpretation of hair findings in children remains very complicated. In this case, it can be assumed that the presence of the drug in the urine indicates systemic incorporation and that administration had occurred for some months (three positive segments). The interpretation of hair tests from young children needs a global review of all the findings, as a positive result cannot stand alone to claim repetitive exposures.

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 × 1 cm segments. The hair test results (3 × 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.

Human hair tests to document drug environmental contamination: Application in a family law case involving N,N-dimethyltryptamine

For 40 years, hair tests have been presented as the best approach to document long-term consumption of a drug. This unique property has found numerous applications in clinical, forensic, and occupational toxicology. However, since the beginning of its implementation in biology, external contamination, with an associated risk of false positive result, has been presented as the key in the final interpretation. Evidence of environmental contamination and subsequent health issues can be the task of any toxicologist. Because of recent progress of analytical equipment, it is now possible to quantify drugs in hair with high level of accuracy and specificity at the pg/mg range. Therefore, segmental hair tests can be used to document environmental contamination and are the objective of this publication. In a family law case, N,N-dimethyltryptamine (DMT), a powerful hallucinogen, has been found in the hair of the partner of a repetitive DMT smoker at 4 to 13 pg/mg in 6 × 1 cm segments, with a regular increase of concentrations from the proximal to the distal hair end. The low measured concentrations and the particular pattern of DMT distribution along the hair shaft seem to be typical of environmental contamination, the older hair (those of the distal part) being for a longer time in contact with the drug. Despite strong decontamination, drugs from the environment can remain bound to the hair matrix and therefore be able to be used to document environmental contamination.

Recent Trends in Analytical Methods to Determine New Psychoactive Substances in Hair

New Psychoactive Substances (NPS) belong to several chemical classes, including phenethylamines, piperazines, synthetic cathinones and synthetic cannabinoids. Development and validation of analytical methods for the determination of NPS both in traditional and alternative matrices is of crucial importance to study drug metabolism and to associate consumption to clinical outcomes and eventual intoxication symptoms. Among different biological matrices, hair is the one with the widest time window to investigate drug-related history and demonstrate past intake.

The aim of this paper was to overview the trends of the rapidly evolving analytical methods for the determination of NPS in hair and the usefulness of these methods when applied to real cases.

A number of rapid and sensitive methods for the determination of NPS in hair matrix has been recently published, most of them using liquid chromatography coupled to mass spectrometry. Hair digestion and subsequent solid phase extraction or liquid-liquid extraction were described as well as extraction in organic solvents. For most of the methods limits of quantification at picogram per milligram hair were obtained. The measured concentrations for most of the NPS in real samples were in the range of picograms of drug per milligram of hair. Interpretation of the results and lack of cut-off values for the discrimination between chronic consumption and occasional use or external contamination are still challenging.

Methods for the determination of NPS in hair are continually emerging to include as many NPS as possible due to the great demand for their detection.

Contribution of in utero drug exposure when interpreting hair results in young children

Hair specimen is necessary to complement blood and/or urine analyses as it permits differentiation of a single exposure from chronic use of a drug by segmentation of the hair for a stated growth period. Moreover, due to a frequent long delay between event and police declaration, hair can be the only solution for lack of corroborative evidence of a committed crime. With the exception of lower amount of biological material in children versus adults, there is no specific analytical problem when processing samples from children. The issue is the interpretation of the findings, with respect to the different pharmacological parameters. In some very young children, the interpretation can be complicated by potential in utero exposure. Twenty-four cases from daily practice have been reviewed. Children were less than 1 year old, hair was always longer than 4 cm and the corresponding mothers admitted having used drugs during pregnancy. Drugs involved include methadone, tramadol, diphenhydramine, diazepam, cannabis, heroin, amitriptyline and bromazepam. Analyses were achieved by hyphenated chromatographic validated procedures after hair decontamination and segmentation. The concentrations measured in the hair of children were lower than those observed in subjects using therapeutically (or illegally) these drugs. In that sense, the frequency of exposures appears as un-frequent (low level of exposure), with marked decrease in the more recent period. However, the parents denied any administration in all cases and there was no reason to suspect re-exposure after delivery and no clinical problem during the period between delivery and hair collection during regular visits to the physician was noticed. The pattern of drug distribution was similar in all these cases, low concentrations in the proximal segments and highest concentration in the distal segment (last segment). When considering the concentration in the distal segment as the 100% of the response (highest concentration), after analysis of 4 segments (irrespective of the length of the segment but longer than 1cm), it was observed the following pattern: proximal segment, 5-35% of the response; segment 2, 15-50% of the response; segment 3, 25-60% of the response; and distal segment, 100% of the response. It is proposed to consider 100% in utero contribution to the final interpretation when the ratio concentration of the proximal segment to the concentration of the distal segment is lower than 0.5. This can be applied only when the child is under 1 year old and the hair shaft length is at least 4 cm (to achieve suitable segmentation). It is important, when using this cut-off to have at least 3 or 4 segments to be able to observe the variation in drug concentrations, whatever the length of each segment (>1cm).