What is GBL?
Gamma-butyrolactone (GBL) or γ-butyrolactone, is a hygroscopic colorless, water-miscible liquid with a weak characteristic odor. It is the simplest 4-carbon lactone. It is mainly used as an intermediate in the production of other chemicals, such as methyl-2-pyrrolidone.
In humans GBL acts as a prodrug for gamma-hydroxybutyric acid (GHB), and it is often used as a recreational drug. The substance is known to act as a central nervous system (CNS) depressant with effects similar to those of barbiturates.
GBL has been found in extracts from samples of unadulterated wines. This finding indicates that GBL is a naturally occurring component in some wines and may be present in similar products.
The concentration detected was approximately 5 μg/mL and was easily observed using a simple extraction technique followed by GC/MS analysis. GBL can be found in cheese flavorings but typically results in a content of 0.0002% GBL in the final foodstuff.
GBL is a prodrug of GHB (naturally produced) and its recreational use comes entirely as a result of this. GBL overdose can cause irrational behaviour, severe sickness, coma and death.
To bypass GHB restriction laws, home synthesis kits were introduced to transform GBL and/or 1,4-B into GHB.
Due to the fact that those with limited chemistry knowledge can make GBL with easy-to-get precursors, it has become quite popular among young people in French nightclubs
Addictiveness and dependence
Frequent use of GHB or GBL, even when taken long-term and in moderate doses, does not appear to cause significant physical dependency in the majority of its users. In many people, quitting or temporarily abstaining from use of the drugs is achieved with minimal or no difficulty.
However, when consumed in excessive amounts with a high frequency of dosing, physical and psychological dependence can develop. Management of GBL dependence involves considering the person’s age, comorbidity and the pharmacological pathways of GBL.
GHB and GBL users can adopt a ’24/7′ dosing regime. This is where the user has become tolerant to the effects of the drug, increasing the dosage and frequency of dosage simply to avoid withdrawal symptoms.
For those users who do report withdrawal symptoms upon quitting the use of GHB or GBL, symptoms seem to depend on the dosage and the length of time the drug was used. Light to moderate users often experience insomnia and sleep-related problems, whereas heavy, prolonged use can cause severe withdrawal symptoms similar to Benzodiazepine withdrawal syndrome.
GBL is rapidly converted into GHB by paraoxonase (lactonase) enzymes, found in the blood. Animals which lack these enzymes exhibit no effect from GBL. GBL is more lipophilic (fat soluble) than GHB, and so is absorbed faster and has higher bioavailability.
Because of these pharmacokinetic differences, GBL tends to be more potent and faster-acting than GHB, but has a shorter duration; whereas the related compound 1,4-butanediol (1,4-B) tends to be slightly less potent and slower to take effect but longer-acting than GHB