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- GHB – amostragem e armazenamento de amostras biológicas de interesse com fins forensesPublication . Castro, André Lobo; Dias, Mário; Reis, Flávio; Teixeira, HelenaO Ácido gama-hidroxibutírico (GHB) é um composto endógeno com um historial de utilização clínica desde os anos 1960’s. No entanto, devido aos seus efeitos secundários, foi classificado como uma substância controlada. É uma substância associada ao consumo ilícito para fins recreativos, para aumento forçado de massa muscular por parte de praticantes de culturismo e ainda ao abuso sexual facilitado por substâncias. A interpretação medico-legal de um resultado positivo para GHB está dependente do seu contexto endógeno e do comportamento post-mortem do composto. Neste pressuposto, serão discutidos os valores endógenos de GHB, quer in-vivo, quer post-mortem, e serão sugeridos alguns cuidados no que diz respeito à amostragem e armazenamento das diferentes amostras biológicas passíveis de ser utilizadas em contexto clínico e forense.
- Endogenous GHB concentrations in whole blood postmortem samples as a biomarker for post mortem interval estimation – A set of real cases analysisPublication . Castro, André Lobo; Tarelho, Sónia; Dias, Mário; Reis, Flávio; Teixeira, HelenaGamma-hydroxybutyric acid (GHB) is an endogenous compound which has a story of clinical use and illicit abuse since the 1960’s. Its postmortem behaviour, namely regarding degradation and metabolism, has been increasingly studied to be used as a putative biomarker for post-mortem interval (PMI) estimation. Thus, whole blood post-mortem GHB levels were obtained in thirty two real cases with previous information on death and autopsy data. The samples were treated through sample methanolic precipitation followed by GC-MS/MS analysis (LLOQ=0.1 mg/L). No differences were encountered for the other parameters evaluated, including age [under 44 years-old - 7.87 2.06 mg GHB/L (n=7), 45 to 60 years-old - 6.80 3.67 mg GHB/L (n=13) and over 61 years-old - 5.72 2.39 mg GHB/L (n=12), p0.05], gender [men - 7.79 5.04 mg GHB/L (n=23), women - 6.72 2.60 mg GHB/L (n=9), p=0.273], cause of death [accident - 7.96 ± 2.26 mg GHB/L (n=8), suicide - 6.75 ± 3.22 mg GHB/L (n=7) and unknown/natural death - 5.14 ± 2.96 mg GHB/L (n=17), p0.05] and presence or absence of substances [absence - 6.37 2.61 mg GHB/L, presence - 6.96 3.38 mg GHB/L, p=0.405]. On the other hand, the results obtained suggest that the PMI (until 5 days between death and sampling) influences GHB whole blood concentration, noticed namely between 48 and 72 hours (24 - 48 hours (p=0.893), 48 - 72 hours (p<0.05); 72 - 96 hours (p=0.123). This study brings additional data regarding the usefulness of GHB levels in forensic toxicology, which might be further strengthened with larger, but comparable, studies from other laboratories and institutions in the forensic toxicology context.
- Quantification of GHB by SPE and GC-MS-MS in whole blood samples for forensic purposesPublication . Castro, André Lobo; Dias, Mário; Reis, Flávio; Teixeira, HelenaIntroduction: Gamma-Hydroxybutyrate (sodium hydroxybutyrate; sodium oxybutyrate; GHB) is known to be an endogenous, naturally occurring, short-chained fatty acid found in mammalian tissues, with wide distribution and action in several brain areas (hipothalamus, basal ganglia). Although it was first synthesised in 1960, it soon was noticed that it is no more than an endogenous compound. With more than 30 years of clinical use, both in Europe and the U.S.A, its illicit use includes recreational use, muscle building effects in bodybuilders and drug-facilitated sexual abuse. Used as a club drug, alone or mixed with other substances, it´s symptoms mimetize MDMA, ketamine and ehtanol. On the ohter hand, it is also used for drug-facilitated sexual abuse (DFSA) purposes. Aim: In this work, the authors developed and validated an analytical procedure for GHB detection in whole blood (in vivo and post-mortem), for forensic purposes. Material and Methods: The analytical method was developed preparing the samples by a SPE procedure with MCX OASIS® cartridges, followed by derivatization with BSTFA-TMCS (99:1) and instrumental analysis developed by GC-MS-MS in a Triple Quadrupole apparatus (BRUKER). Results and Discussion: The described method shows good fitness for purpose for whole blood samples. The obtained LOD and LOQ were 200 ng/mL, for 100 uL of sample. This increase in sensitivity was obtained due to an optimized SPE procedure and an instrumental technique state-of-the-art. The work range started at 200 ng/mL, far below the suggested cut-off for whole blood samples (5-10 mg/L). These results will allow the possibility to distinguish post-mortem production, endogenous values and external consumption, whenever this diagnosis should be determined, being applicable to forensic purposes.