After the FDA imposed restrictions on GHB and will be placed on the regulated list, users have gradually shifted their GHB use to gammatolactone (GBL) and 1, 4-butanediol (BDO), both of which are metabolized to GHB by ingestion
Not only is GBL a direct precursor to GHB synthesis, it is designated as a Class I controlled chemical, while 1, 4-butanediol (BDO) remains unregulated.