Descendants of decamethonium.

W ITH perhaps one exception, decamethonium has been the parent of the main neuromuscular blocking agents introduced, since its discovery, for clinical trial as muscle-relaxants. Its descendants (see fig. 1) include suxamethonium (succinylcholine), suxethonium (362 I.S.), Ro 3-0386 and Laudolissin. The exception (fig. 2) is benzoquinonium (Mytolon), which was derived from an experimental anti-bacterial substance by the chemical process of quaternization (Hoppe, 1951). Since benzoquinonium has the practical disadvantage of causing excessive salivation and bronchorrhea (Foldes, 1951; Robertazzi, 1951), the new relaxants at present in use appear all to be descendants of decamethonium. Chemists have found decamethonium a useful starting point because it combines simplicity of structure with high potency. Its molecule not only represents one of the simplest forms imaginable to block the neuromuscular junction potently; but it is the most powerful relaxant yet used clinically, being two to three times as strong as d-dimethyltubocurarine and four to five times as d-tubocurarine itself. In developing new compounds, some of the simplicity and potency of decamethonium can be comfortably exchanged for other desirable features which this drug lacks. That decamethonium does lack certain desirable features is evident from its comparative failure to win favour