The antagonism of muscle relaxants by ambenonium and methoxyambenonium in the cat.

The ability of ambenonium and a methoxy analogue to antagonize paralysis produced either by tubocurarine or by decamethonium has been studied in the tibialis anterior muscle of the cat under chloralose anaesthesia. In small doses, both oxamides facilitated neuromuscular transmission, but in larger doses they depressed the sensitivity of the motor end plates to depolarizing substances and it is considered that this latter action is sufficient to account for their anti-decamethonium action. Although both compounds possess anticholinesterase activity, there was found to be no correlation between their relative abilities to antagonize tubocurarine paralysis and their abilities to inhibit muscle cholinesterase in vitro.