Gammahydroxybutyrate in hair of non-GHB and repeated GHB users: A new and optimized method

Gamma-hydroxybutyric acid (GHB) is a short-chain fatty acid used recreationally as a drug of abuse due its strong suppressive effect on the central nervous system. The detection window of GHB in blood and urine is very narrow (t1/2 = 30 min) but can be substantially prolonged using alternative matrices such as hair. We here present a newly developed and limited validated method with a solid phase extraction (SPE) using GC-MS/MS to determine concentrations of GHB in hair samples. The soft extraction technique (water and 90 min ultrasonic bath) preserves GHB with a high yield and clean extracts. In addition, endogenous GHB can be detected in hair of non-GHB users. However, little is known about GHB concentrations in hair of abstinent, frequent and chronic GHB users. Therefore, we present data from hair samples of healthy volunteers to evaluate the proposed endogenous GHB ranges, and from GHB-dependent patients to address GHB concentrations in hair with GHB intake. In 20 non-GHB users, a mean endogenous concentration of 1.1 ± 0.6 ng/mg hair (range of 0.3-2 ng/mg) was found. In GHB-dependent patients, concentrations between 6.3-239.6 ng/mg hair were found, with no correlation between concentrations in hair and dose of GHB intake. In summary, we present a new and limited validated method, adequately sensitive for the detection of GHB in hair, as well as first-time measurements of GHB concentrations in dependent patients in order to better understand the relationship between the frequency of use/dose and concentrations observed in hair samples.