After I.V. injection, the onset of effects is rapid. Motor weakness rapidly progresses to flaccid paralysis. Small muscles such as those of the fingers and extraocular muscles of the eyes are effected before those of the limbs, neck, and trunk. Subsequently, the intercostal muscles and finally the diaphragm is paralyzed. Recovery of function occurs in the reverse order, with the diaphragm recovering first.
Death is due to paralysis of the muscles of respiration.
C. CNS effects 1. Almost all contain a quaternary nitrogen therefore they do not cross the blood brain barrier. D. Effects on Autonomic Ganglia 1. Although tubocurarine is more potent at Nm receptors than at Nn receptors of ganglia, some degree of nicotinic receptor blockade is probably produced at autonomic ganglia and the adrenal medulla by usual clinical doses. The net result is hypotension and tachycardia.