Neuromuscular Blocking Agents

NSN- and NNN-Tris-onium compounds related to dihexasulphonium and dihexazonium in which N-alkyl substituents are varied have been synthesised. All compounds tested qualitatively resembled tubocurarine in their action. Stepwise replacement of Et by Me in dihexasulphonium tri-ethiodide decreases potency and some C 10-like effects appear in compounds Xaand Xb. Potency also falls when Et groups are replaced successively by n-Pr in both dihexasulphonium tri-ethiodide and dihexazonium tri-ethiodide, compounds XIfand XIgbeing the least active of the series and approximately equipotent with dihexasulphonium trimethiodide (Xa). Replacement of one Et group by n-Bu at each quaternary ammonium centre of dihexazonium, as in compound XIcincreases potency.