Gammabutyrolactone (GBL) is closely related to Gammahydroxybutrate (GHB) with much the same effects. GBL converts to GHB soon after entering the body. It is a drug with sedative and anaesthetic effects. It is a colourless liquid with a weak odour. <br><br> GBL is not classified in the UK. It is a legal product used in industry and probably available from other sources such as internet sites. The Advisory Council on the Misuse of Drugs has recommended that GBL should also be controlled as a Class C drug.