Mivacurium is awesome, it's nice and short, WHY WAS IT DISCONTINUED? SERIOUSLY! It's not like it caused fatal bronchospasms or anything...
It's a bis-benzyltetrahydroisoquinoline :) The chemical formula is C58H80N2O14. Like succinylcholine, it is broken down by plasma pseudocholinesterase, which is very bad if you have a pseudocholinesterase deficiency. It's especially bad if someone with the deficiency gets succinylcholine for intubation and then mivacurium as the main NMB, nice double whammy there.
Mivacurium was first FDA approved on January 22, 1992. It is discontinued in the US, but not for health reasons or potentially dangerous side effects. Who knows; maybe mivacurium or a drug like it could return someday, if the discontinuation isn't permanent.
Mivacurium is mentioned in the show Nip/Tuck in Season 2 episode 15 when the Carver states that he uses a modified version of it on his victims. They probably said it was a "modified version" to get around the fact that real mivacurium would kill you, and it wouldn't last only 1-2 minutes.
Vickie Dawn Jackson, a nurse and serial killer, on the other hand, did use real mivacurium to kill several patients.