Gamma butyrolactone (GBL) is a chemical compound that can be synthesized in laboratories but can also be found in unadulterated wines. On its own, gamma butyrolactone does not have any effects. Nevertheless, when it is absorbed into the blood, it is subjected to the action of lactonase enzymes. These enzymes catalyze the conversion of gamma butyrolactone into gamma hydroxybutyric acid (GHB).
As a prodrug of GHB, gamma butyrolactone is sometimes referred to as dehydrated GHB. As indicated by the term “dehydrated,” GBL does not contain as much water as GHB, and is therefore more fat-loving, or lipophilic. Compared with GHB, GBL is absorbed faster when consumed with food. This causes it to produce the desired effects faster. The duration of action of gamma butyrolactone, however, is also shorter than that of its counterpart.
The effects of gamma butyrolactone are based on its property as a prodrug of GHB. GHB is similar to the naturally produced neurotransmitter called gamma aminobutyrate (GABA). GABA is produced by the brain and acts on receptors to block nerve impulses, thereby earning the label “inhibitory” neurotransmitter. The effects of GABA include relaxation, sleep, an increased feeling of well-being, decreased anxiety and decreased muscle tone. Furthermore, GABA release is associated with increased levels of growth hormone.
The only difference between GHB and GABA is the substitution of a hydroxyl group in the former. GHB readily crosses the blood-brain barrier and acts on the same receptors on which GABA acts. Therefore, GHB also potentially leads to relaxation, sleep and growth hormone release from the pituitary gland. Research has shown that when gamma butyrolactone is taken in therapeutic doses, the elevation of growth hormones can reach as much as five times the average levels. An increase in growth hormones is best for bodybuilders and other athletes because growth hormones promote the utilization of fat stores and the development of lean muscles.
It can be converted to GHB and can increase growth hormone levels, so gamma butyrolactone was widely marketed during the 1990s as a nutritional supplement. At low doses that range from 500-1,500 milligrams, the intake of GBL or GHB can promote relaxation. At medium doses that range from 1,000-2,500 milligrams, the resulting muscle relaxation can give a person a decreased sense of balance and decreased coordination. At high doses, a person would experience adverse effects that include nausea; vomiting; decreased breathing rate, or bradypnea; decreased heart rate, or bradycardia; and seizures. The worst outcomes are coma and death.
The National Institute on Drug Abuse and the United States Food and Drug Administration have labeled gamma butyrolactone, GHB and other associated substances as dangerous drugs. As such, they have been banned from the market. GABA, by itself, is still considered legal as an amino acid supplement.