Initial evaluation of 4-palmitoyloxy butyrate in whole blood as potential biomarker after γ-hydroxybutyric acid intake.

This article evaluates the potential of 4-palmitoyloxy butyrate (GHB-Pal), a fatty acid ester of γ-hydroxybutyric acid (GHB), as a biomarker to extend the detection window of GHB intake in whole blood, particularly relevant in forensic toxicology and drug-facilitated sexual assault (DFSA) cases. Using a validated liquid chromatography–tandem mass spectrometry (LC–MS–MS) method, GHB-Pal was detected in some police roadside blood samples with GHB concentrations above 16 µg/mL but showed no linear correlation with GHB levels; it was not detected in blood samples from narcolepsy patients after controlled therapeutic GHB (Xyrem®) administration, likely due to timing and dosage. The study concludes that GHB-Pal is not a suitable biomarker for prolonging the detection window of GHB in blood, given its low concentrations, lack of correlation with GHB, and absence several hours post-administration.