Research and development of aminosteroid neuromuscular blocking agents: past and future

This article attempts to summarize more than 25 years of chemistry and pharmacology research aimed at the search for clinically useful muscle relaxants based on an amino-androstane skeleton. This research strategy has produced three clinically useful drugs (pancuronium, vecuronium and rocuronium), and in addition has demonstrated that it is indeed possible to design a non-depolarizing neuromuscular blocker with the onset/offset characteristics of suxamethonium. Lastly, much has been learned about the variable clinical predictiveness of data obtained in various animal species with these compounds. This factor is probably mainly responsible for the difficulties and delay in producing the non-depolarizing suxamethonium equivalent.