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Gamma-Butyrolactone: Wikis


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IUPAC name
Other names GBL, butyrolactone, 1,4-lactone, 4-butyrolactone, 4-hydroxybutyric acid lactone, and gamma-hydroxybutyric acid lactone
CAS number 96-48-0 Yes check.svgY
RTECS number LU3500000
Molecular formula C4H6O2
Molar mass 86.089 g/mol
Appearance Colorless oily liquid
Density 1.1286 g/mL (15 °C)
Melting point

-43.53 °C, 230 K, -46 °F

Boiling point

204 °C, 477 K, 399 °F

Solubility in water Miscible
MSDS External MSDS
R-phrases R22 R36
S-phrases S26 S36
Flash point 98 °C (closed cup)
LD50 17.2 mL/kg (orally, rat)
 Yes check.svgY (what is this?)  (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

gamma-Butyrolactone (γ-butyrolactone or GBL) is a hygroscopic colorless oily liquid with a weak characteristic odor and is soluble in water. GBL is a common solvent and reagent in chemistry and is used as an aroma compound, as a stain remover, as a superglue remover, as a paint stripper, and as a solvent in some wet aluminium electrolytic capacitors. In humans it acts as a prodrug for GHB, and it is used as a recreational intoxicant.



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 synthesized from gamma-hydroxybutyric acid (GHB) by removal of water or by distillation from such a mixture. It may also be obtained via oxidation of tetrahydrofuran (THF). One such process, which affords GBL in yields of up to 80%, utilises bromine generated in situ from an aqueous solution of sodium bromate and potassium hydrogen sulfate.[2]


GBL is a lactone. It is hydrolyzed under basic conditions, for example in a sodium hydroxide solution into sodium gamma-hydroxybutyrate, the sodium salt of gamma-hydroxybutyric acid. Under acidic conditions it forms an equilibrium mixture of both compounds. These compounds then may go on to form a polymer.


GBL is not active in its own right, its mechanism of action stems from its identity as a prodrug of GHB.

The hypnotic effect of GHB is enhanced by combination with alcohol. A 2003 rat study showed that GBL in combination with ethanol showed a potentiated hypnotic effect, as the sleep-timing measure was longer than both of the individual components combined.[3]


GBL is rapidly converted into GHB by lactonase enzymes found in the blood. GBL is more lipophilic (fat soluble) than GHB, and so is absorbed faster and has higher bioavailability; the paradox is that this can mean that GBL has a faster onset of effects than GHB itself, even though it is a prodrug. The levels of lactonase enzyme can vary between individuals, and GBL is not active in its own right, so people who have never tried GBL before may have delayed or fewer effects than expected; however, once someone has taken GBL a few times, the production of lactonase enzymes is increased and he/she will feel the effects as normal.

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, slower to take effect but longer-acting than GHB.

Use as a nutritional supplement

Due to its property of being a prodrug of GHB, GBL was sold as a nutritional supplement after the scheduling of GHB, under the names Revivarant and Renewtrient in the U.S. at least until the end of 1999.

GBL (as well as GHB), when taken internally in therapeutic doses without the presence of other drugs (especially alcohol, as mixing the two can be fatal), has been shown to elevate growth hormone levels in humans to at least 5 times the baseline.

Recreational use

GBL is a prodrug of GHB. To bypass GHB restriction laws, home synthesis kits were introduced to transform GBL and/or 1,4-B into GHB. GBL can also be used as a recreational drug by itself.[4]

Jugs of seized GBL.
FDA warning against products containing GHB and its prodrugs, such as GBL.

GBL overdose can cause severe sickness, coma and death. [5]

Metabolism takes place in stomach and blood plasma. GBL is longer acting and has a shorter onset than GHB. Otherwise, effects are similar to GHB, although weight for weight it is significantly more powerful, meaning dosage must be lowered accordingly. If taken undiluted by mouth, GBL can cause esophageal and gastro-intestinal irritation. It is possible for oral ingestion of GBL to cause nausea and other similar problems, possibly more so than with GHB.

Excessive use

GHB (gamma hydroxybutyrate) and GBL (gamma butyrolactone) are substances which are often used as recreational drugs. GHB has two effects, at low doses it has a euphoric effect (which is why it is sometimes referred to as liquid ecstasy). At higher doses it acts like a sedative and can make the user unconscious very quickly.


If used frequently it can cause physical dependency. Currently not much is known about GHB/GBL dependency syndrome. It can be characterized as “round the clock” use, where users may have to dose from as frequently as every forty minutes to an hour. This is because withdrawal symptoms can begin as quickly as 40 minutes from the last dose. There appears to be a temporal pattern of withdrawal symptoms which include extreme anxiety, sleeplessness, feeling shaky, confusion, nausea and vomiting. In addition further withdrawal symptoms may include auditory and visual hallucinations, delirium and psychosis. These symptoms can be mistaken for psychosis as GHB/GBL can be difficult to detect in the system. Withdrawal from GHB/GBL is similar to withdrawal from severe alcohol dependency.

Withdrawal symptoms seem to increasingly begin quicker if GHB/GBL is used "round the clock" for an extended period of time, like several years.

Dangers from withdrawal symptoms: As with chronic alcohol addiction, withdrawal from GHB/GBL dependency should be done under medical supervision and preferably on an inpatient basis. It can be dangerous to suddenly stop taking GHB/GBL. In addition care should be taken when using GHB/GBL with other substances including alcohol as this could easily result in accidental overdose.

Withdrawal times: varies depending on a range of factors but is usually between 5–10 days. Some users who have taken GHB/GBL for several years reportedly feel withdrawal symptoms for up to six months after they stop taking it, although not as intense as the initial symptoms.

The recommended treatment; is to stabilise symptoms of anxiety and psychotic symptoms. High doses of diazepam are usually indicated to control psychotic agitation. Patients with GHB/GBL dependency have a high tolerance to the sedating effects of benzodiazepines and require large doses similar to those for alcohol dependency. Patients also require frequent monitoring of their symptoms.

Long term recovery: early reports are that recovery from dependant use is promising after detoxification, although this is an area which needs more research.

Clients with GHB/GBL dependency should contact a doctor for medical advice. Under no circumstances should excessive users stop dosing themselves until they've seen a doctor or medical professional.


A millilitre of pure GBL metabolizes to roughly 1.6g of GHB, so doses are measured in the single milliliter range, either taken all at once or sipped over the course of a night. GBL has a distinctive taste and odour, described as stale water or burnt plastic.

Legal status of GBL

Canada: GBL is a Controlled Substance under Schedule VI of the "Controlled Drugs and Substances Act" in Canada. Schedule VI of the "Controlled Drugs and Substances Act" requires vendors to collect information regarding purchases of GBL. It is not illegal for an individual to possess GBL in Canada.

United Kingdom: GBL will be classified as a Class C drug from 23 December 2009, with a prison term of up to two years for possession and 14 years for dealing, by the end of 2009.[6]

Sweden: GBL is not classified as a drug but as a health-endangering substance.[7]

See also


  1. ^ Merck Index, 12th Edition, 1632.
  2. ^ Metsger, L.; Bittner, S. Autocatalytic Oxidation of Ethers with Sodium Bromate, Tetrahedron 2000, 56, 1905-1910
  3. ^ Sassenbroek, Van (June 2007), "Characterization of the pharmacokinetic and pharmacodynamic interaction between gamma-hydroxybutyrate and ethanol in the rat.", Toxicological Sciences, PMID 12700396  
  4. ^ Meyer, Jerrold; Linda F. Quenzer (2005). Psychopharmacology: Drugs, the Brain and Behavior. Sinauer. p. 370. ISBN 0-87893-534-7.  
  5. ^
  6. ^ The Misuse of Drugs Act 1971 (Amendment) Order 2009
  7. ^ GBL

External links

  • Erowid on GBL
  • BBC News story: The paint stripper drug that kills, October 7, 2005.
  • “All About GHB," a NIDA Neuroscience Consortium and OSPC “Cutting Edge” colloquium (27 June 2000 at the Doubletree hotel, Rockville, MD) Organized by Drs. Jerry Frankenheim and Minda Lynch in response to the rapid ascent of GHB and its precursors, GBL and 1,4-butanediol, as public health concerns.

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