Deacetylating vecuronium at position 3 results in a very active metabolite. In the case of rapacuronium the 3-deacylated metabolite is even more potent than rapacuronium. As long as the D-ring acetylcholine moiety is unchanged they retain their muscle relaxing effect. "Mono"-quaternary aminosteroids produced with deacylation in position 17 on the other hand are generally weak muscle relaxants. In the development of atracurium the main idea was to make use of Hofmann elimination of the muscle relaxant "in vivo". When working with bisbenzyl-isoquinolinium types of molecules, inserting proper features into the molecule such as an appropriate electron withdrawing group then Hofmann elimination should occur at conditions "in vivo". Atracurium, the resulting molecule, breaks down spontaneously in the body to inactive compounds and being especially useful in patients with kidney or liver failure. "Cis"-atracurium is very similar to atracurium except it is more potent and has a weaker tendency to cause histamine release.