GBL

Gamma-butyrolactone (GBL) is a lactone and solvent used in various industries, such as polymers. It was first synthesised in the early 20th century for industrial applications. However, it wasn’t until later in the 20th century that GBL was recognised for its psychoactive properties, as it is metabolised into gamma-hydroxybutyrate (GHB) in the body, a substance with potent effects on the central nervous system.¹

GBL, acting as a prodrug of GHB, induces effects similar to its parent compound, ranging from mild euphoria and relaxation at low doses to severe sedation and unconsciousness at higher doses.² Its use as a recreational drug is often related to these effects.

However, GBL carries significant health risks. Acute intoxication can be potentially lethal, and there have been instances where its consumption has led to end-stage renal failure.³ Moreover, the regulatory status of GBL is complex and varies across jurisdictions, leading to both legal and medical confusion.⁴

GBL is typically consumed orally, often mixed with water or other beverages due to its strong and unpleasant taste.⁵

• Minimum to Feel Something (mg): The precise dosage for initial effects can vary significantly between individuals, but generally, consumption of around 0.5-1 grams might produce noticeable effects.⁶
• Low Dose: A low dose typically ranges from 0.5 to 1.5 grams of GBL. This dosage might produce mild effects in some individuals.⁶
• Common Dose: A common dose of GBL for recreational use is between 1 and 2.5 grams.⁶
• High Dose: A high dose refers to the consumption of around 3 grams or more of GBL, which can lead to severe effects, including unconsciousness and potential overdose.^{6, 7}

Notes on what may happen when exceeding the high dose:
Exceeding the high dose of GBL can lead to severe effects, including respiratory depression, seizures, unconsciousness, and, in some cases, death. Fatalities have been reported even at doses as low as 3 grams, especially when mixed with other depressants like alcohol. ⁷

The effects of GBL can range from feelings of euphoria and reduced inhibitions to drowsiness, confusion, and memory loss. Some people also experience an increase in libido.⁵

Physical effects can include drowsiness, nausea, vomiting, unsteady gait, and slowed breathing. Severe cases can lead to seizures, respiratory depression, and coma.

GBL typically begins to take effect within 15-30 minutes after ingestion. ⁹

The effects of GBL typically last 2-4 hours, although this can vary depending on the dose taken and individual metabolism.⁹

Risks associated with GBL include unconsciousness, seizures, respiratory depression, and fatal overdose. Chronic use can lead to physical dependence and withdrawal symptoms upon cessation.⁷

GBL can be highly addictive. Regular use can lead to physical dependence, characterised by a withdrawal syndrome upon cessation that includes insomnia, anxiety, tremors, and hallucinations.⁸

In the UK, GBL is a Class C drug, making it illegal to supply or produce. It is also illegal to own GBL with the intent to supply. GBL is not illegal to possess for personal use, but because it’s often used as a ‘date rape’ drug, police can charge people under different laws.⁴

GBL should not be combined with alcohol or other central nervous system depressants, as these combinations can significantly increase the risk of unconsciousness, respiratory depression, and overdose.⁴

1. Lettieri, J., and Fung, H.L., 1978. Improved pharmacological activity via pro-drug modification: Comparative pharmacokinetics of sodium gamma-hydroxybutyrate and gamma-butyrolactone. Research Communications in Chemical Pathology and Pharmacology, 22(1), pp. 107-118. https://pubmed.ncbi.nlm.nih.gov/697450
2. Schep, L.J., et al., 2012. The clinical toxicology of gamma-hydroxybutyrate, gamma-butyrolactone, and 1,4-butanediol. Clinical Toxicology, 50(6), pp. 458-470. https://pubmed.ncbi.nlm.nih.gov/22746383/
3. Knudsen, K., et al., 2008. Gamma-butyrolactone-induced End-stage Renal Failure. Basic & Clinical Pharmacology & Toxicology, 103(3), pp. 267-269. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1742-7843.2008.00262.x
4. Wood, D.M., et al., 2011. Medical and legal confusion surrounding gamma-hydroxybutyrate (GHB) and its precursors gamma-butyrolactone (GBL) and 1,4-butanediol (1,4-BD). QJM: An International Journal of Medicine, 104(9), pp. 761-769. https://pubmed.ncbi.nlm.nih.gov/18203723/https://academic.oup.com/qjmed/article/104/10/867/1591864
5. Degenhardt, L., et al., 2002. GHB use among Australians: characteristics, use patterns, and associated harm. Drug and Alcohol Dependence, 67(1), pp. 89-94. https://pubmed.ncbi.nlm.nih.gov/12062782/
6. Busardò, F.P., and Jones, A.W., 2015. GHB Pharmacology and Toxicology: Acute Intoxication, Concentrations in Blood and Urine in Forensic Cases, and Treatment with a Novel GHB-Receptor Antagonist. Pharmacology Biochemistry and Behavior, 134, pp. 1-8. https://pubmed.ncbi.nlm.nih.gov/26074743/
7. Zvosec, D.L., et al., 2011. Case series of 226 gamma-hydroxybutyrate-associated deaths: lethal toxicity and trauma. The American Journal of Emergency Medicine, 29(3), pp. 319-332. https://www.researchgate.net/publication/288351185_Case_series_of_226_gamma-hydroxybutyrate-associated_deaths_lethal_toxicity_and_trauma
8. McDonough, M., et al., 2004. Clinical features and management of gamma-hydroxybutyrate (GHB) withdrawal: a review. Drug and Alcohol Dependence, 75(1), pp. 3-9. https://pubmed.ncbi.nlm.nih.gov/15225884/
9. Andresen, H., et al., 2011. An overview of gamma-hydroxybutyric acid: pharmacodynamics, pharmacokinetics, toxic effects, addiction, analytical methods, and interpretation of results. Drug Testing and Analysis, 3(7-8), pp. 560-568. https://pubmed.ncbi.nlm.nih.gov/21381220/