Uptake of gamma-valerolactone--detection of gamma-hydroxyvaleric acid in human urine samples.

Gamma-valerolactone (GVL) is reported to be a substance that can be used as a legal substitute for gamma-hydroxybutyric acid (GHB), which is currently a controlled substance in several countries. Unlike gamma-butyrolactone and 1,4-butanediol, GVL is not metabolized to GHB, which causes the effects after uptake of these two chemicals. In the case of GVL, the lactone ring is split to gamma-hydroxyvaleric acid (GHV or 4-methyl-GHB) by a lactonase. Because of its affinity for the GHB receptor, GHV reveals similar effects to GHB, although it is less potent. Intoxications with GVL, or its use as a date rape drug, are conceivable. Despite these facts, there are no publications in the literature regarding detections of GHV in human samples. This study reports three cases, including five urine samples, in which GHV could be detected in concentrations between 3 and 5.8 mg/L. In one of these cases, a drug-facilitated sexual assault (DFSA) was assumed; four of these samples were from two people suspected of abusing GHB. The results indicate that GVL is used as an alternative to GHB and its precursors and should be taken seriously. GVL or GHV should be included in toxicological analysis, particularly in DFSA cases. More information is needed regarding the pharmacokinetics of GVL/GHV for the meaningful interpretation of positive or negative results.