title: Gamma-hydroxybutyric acid endogenous production and post-mortem behaviour - the importance of different biological matrices, cut-off reference values, sample collection and storage conditions.
abstract: Gamma-Hydroxybutyric Acid (GHB) is an endogenous compound with a story of clinical use, since the 1960's. However, due to its secondary effects, it has become a controlled substance, entering the illicit market for recreational and "dance club scene" use, muscle enhancement purposes and drug-facilitated sexual assaults. Its endogenous context can bring some difficulties when interpreting, in a forensic context, the analytical values achieved in biological samples. This manuscript reviewed several crucial aspects related to GHB forensic toxicology evaluation, such as its post-mortem behaviour in biological samples; endogenous production values, whether in in vivo and in post-mortem samples; sampling and storage conditions (including stability tests); and cut-off reference values evaluation for different biological samples, such as whole blood, plasma, serum, urine, saliva, bile, vitreous humour and hair. This revision highlights the need of specific sampling care, storage conditions, and cut-off reference values interpretation in different biological samples, essential for proper practical application in forensic toxicology.
authors.affiliation: National Institute of Legal Medicine and Forensic Sciences, Forensic Chemistry and Toxicology Service, Portugal; CENCIFOR - Forensic Sciences Centre, Coimbra, Portugal. Electronic address: andre.castro@inml.mj.pt.
authors.forename: André L
authors.initials: AL
authors.lastname: Castro
authors.affiliation: National Institute of Legal Medicine and Forensic Sciences, Forensic Chemistry and Toxicology Service, Portugal; CENCIFOR - Forensic Sciences Centre, Coimbra, Portugal.
authors.forename: Mário
authors.initials: M
authors.lastname: Dias
authors.affiliation: Laboratory of Pharmacology & Experimental Therapeutics, IBILI, Faculty of Medicine, University of Coimbra, Coimbra, Portugal; Faculty of Medicine, University of Coimbra, Coimbra, Portugal.
authors.forename: Flávio
authors.initials: F
authors.lastname: Reis
authors.affiliation: National Institute of Legal Medicine and Forensic Sciences, Forensic Chemistry and Toxicology Service, Portugal; CENCIFOR - Forensic Sciences Centre, Coimbra, Portugal; Faculty of Medicine, University of Coimbra, Coimbra, Portugal; Faculty of Medicine, University of Porto, Porto, Portugal.
authors.forename: Helena M
authors.initials: HM
authors.lastname: Teixeira
mesh_terms: D001646:Bile / Q000378:metabolism; D053593:Forensic Toxicology; D006197:Hair / Q000378:metabolism; D006801:Humans; D006885:Hydroxybutyrates / Q000378:metabolism*; D011180:Postmortem Changes; D012016:Reference Values; D012463:Saliva / Q000378:metabolism; D013048:Specimen Handling; D014822:Vitreous Body / Q000378:metabolism
chemical_list: D006885:Hydroxybutyrates; C111420:4-hydroxybutyric acid
keywords: Cut-off reference values; Endogenous and post-mortem behaviour; Forensic toxicology; Gamma-hydroxybutyric acid (GHB); Sample collection; Storage conditions