Further studies on the pharmacological properties of onium salts

Abstract

The curariform activity of equimolar solns. of tetra-alkyl onium salts was compared by measuring the times required completely to paralyse to indirect stimulation isolated nerve-sartorius preparations of winter frogs (R. esc). When R = Me, R4N[image] > R4P[image] > R4As[image], when R=Et, the order is reversed. Millimolar solns. of R4N[image] (R=Me, Bu), R4P[image](R = Pr, Bu), R4As[image](R = Et, Pr) and Ph2I[image] paralyse the preparations in 6[plus or minus]0.5 min. Millimolar Pr4N[image], Me4P[image], Et4P[image] and Me3S[image] take 11.5, 17, 40 and 16 min. respectively. Millimolar Et4N[image] and Et3S[image] are without action and Me4As[image] does not paralyse completely. Pyridine and quinoline ethiodides are more active than the corresponding methiodides, but N-methyltetrahydroquinoline ethiodide is less active than the corresponding methiodide. Alkylquinolinium salts (alkyl = Pr, Bu, Oct) are equal to Me4N[image] salts in activity. Strychnine methiodide shows a much higher order of activity than any other onium salts examined. The theoretical bearing of these results is discussed. Cations Me3N[image]R (where R=Me, Et, Pr, Bu, Amyl, Hexyl, Octyl, phenyl, benzyl, and [beta]-phenylethyl) all produce contracture of recti abdominis (R. temp.) in millimolar solns. Me4N[image]=Me3S[image] > Me4P[image] > Me4As[image] and MesN[image]R (R=Me, Et, Pr, Bu, Am) are equal and > Me3NH2 > Me3NOct. Cations R4N[image], R4P[image] and R4As[image](R=Et, Pr), Et3S and Ph2I[image] are inactive, and so are onium salts derived from pyridine and quinoline.