In New Zealand and Australia, GHB, 1,4-B, and GBL are all Class B illegal drugs, along with any possible esters, ethers, and aldehydes. GABA itself is also listed as an illegal drug in these jurisdictions, which seems unusual given its failure to cross the blood–brain barrier, but there was a perception among legislators that all known analogues should be covered as far as this was possible. Attempts to circumvent the illegal status of GHB have led to the sale of derivatives such as 4-methyl-GHB (γ-hydroxyvaleric acid, GHV) and its prodrug form γ-valerolactone (GVL), but these are also covered under the law by virtue of their being "substantially similar" to GHB or GBL and; so importation, sale, possession and use of these compounds is also considered to be illegal.