Gamma-Butyrolactone (GBL) is an industrial chemical that is commonly used as a solvent and chemical intermediate in the production of other chemicals, such as pyrrolidones, and is found in paint removers, cleaners, adhesives, and nail polish removers. It is also used as a body- or muscle-builder and as a recreational drug. GBL is converted to gamma-hydroxybutyrate (GHB) in the body, which is a central nervous system depressant with effects similar to those of barbiturates. GBL is classified as a Schedule I controlled substance in the US, making it illegal. GBL is also used as a precursor for clandestine manufacturing of GHB.