The synthesis and pharmacology of some 1,4,5,6-tetrahydropyrimidines.

1. Several 1- and 2-substituted, and 1,2-disubstituted, 1,4,5,6-tetrahydropyrimidines have been prepared and their toxicological and pharmacological properties have been investigated.2. In general the compounds were neuromuscular blocking agents with the monosubstituted members of the series showing a depolarizing type of activity and the disubstituted compounds a non-depolarizing type.3. The toxicity to mice of some of the monosubstituted compounds was increased by pretreatment of the animals with SKF 525A, but the toxicity of the disubstituted compounds was unaffected.4. The results obtained with these compounds are not at variance with a suggestion made previously that nicotinic action at the neuromuscular junction can result from an interaction between drug and receptor at two points separated by about 4 A.