Anticholinergic actions of steroid muscle relaxants.

The chronotropic effects of two new steroid muscle relaxants have been investigated. Each was compared individually with pancuronium bromide, using acetylcholine as an agonist on the isolated perfused rabbit heart. One of the drugs. Organon 6368, was very similar to pancuronium in its degree of antagonism to the bradycardia produced by acetylcholine and may therefore be a useful drug clinically. Dacuronium, on the other hand, would appear to have marked chronotropic effects at dose levels needed for adequate neuromuscular blockade and thus may be less useful.