Interpreting γ-hydroxybutyrate concentrations for clinical and forensic purposes

Area of Science:

• Forensic Toxicology
• Clinical Chemistry
• Pharmacology

Background:

• γ-Hydroxybutyric acid (GHB) is an endogenous substance with therapeutic uses and potential for abuse.
• GHB acts as a central nervous system depressant, frequently encountered in clinical and forensic settings.
• Accurate interpretation of GHB concentrations is crucial for diagnosing intoxication and in legal investigations.

Purpose of the Study:

• To provide clinical and forensic practitioners with guidance on interpreting GHB concentrations.
• To review analytical methods for GHB detection in various biological specimens.
• To establish reference ranges and cut-off values for GHB in different matrices.

Main Methods:

• Comprehensive literature search of PubMed, Scopus, and Web-of-Science for GHB analysis.
• Evaluation of analytical techniques, primarily chromatography coupled with mass spectrometry (GC-MS, LC-MS).
• Review of pharmacokinetic data, including absorption, distribution, and elimination half-life of GHB.

Main Results:

• GHB analysis in blood, urine, and alternative specimens (CSF, saliva, hair, etc.) is feasible with sensitive methods (LOQ ≤ 0.5 mg/L).
• Short elimination half-life (0.5-0.9 h) necessitates timely specimen collection.
• Concentrations vary significantly between impaired drivers and intoxication deaths, with higher levels in the latter.

Conclusions:

• Rapid collection of biological specimens is essential for accurate GHB detection.
• Alternative specimens like urine, vitreous humor, and CSF offer stability in postmortem cases.
• Establishing appropriate cut-off concentrations is vital to differentiate endogenous GHB from drug abuse.