In vitro production of gamma-hydroxybutyrate in antemortem blood under various storage conditions.

This article focuses on the stability and in vitro production of gamma-Hydroxybutyrate (GHB) in antemortem blood samples under various storage conditions and its implications for forensic toxicology, particularly impaired driving investigations in Canada. GHB, an endogenous central nervous system depressant with a legal blood per se limit of 5 mg/L in Canada, can increase in concentration post-collection due to in vitro production, especially in unpreserved blood stored at room temperature (21°C) or refrigerated (4°C). The study found that the presence of preservative (sodium fluoride) effectively minimized GHB production over 306 days, while unpreserved samples showed significant increases, reaching up to 10 mg/L at 4°C and rising rapidly at 21°C. Analysis of 22 impaired driving cases in Ontario revealed that most GHB concentrations exceeded levels attributable to in vitro production, but concentrations below 10 mg/L in unpreserved samples stored for extended periods warrant cautious interpretation considering storage conditions, preservative use, and time between collection and analysis.