On the pharmacology of Org 6368 (2β, 16β ‐ dipiperidino ‐ 5α ‐ androstan ‐ 3α ‐ ol acetate dimethobromide), a new steroidal neuromuscular blocking agent

Org 6368 is a homologue of pancuronium bromide. Its interactions with other agents in the cat sciatic nerve‐gastrocnemius muscle preparation revealed that paralysis was of the non‐depolarizing type. This was confirmed in experiments using avian muscle. Org 6368 is a potent muscle relaxant being 2·4 times as potent as (+)‐tubocurarine in the cat. Paralysis in the cat is rapid in onset and of appreciably shorter duration than that of pancuronium and (+)‐tubocurarine. Repeated injections of the same dose of Org 6368 show no cumulative effect. Muscle relaxant doses generally cause a slight increase in both blood pressure and heart rate. Although its histamine‐releasing capacity is greater than that of pancuronium it is less than that of (+)‐tubocurarine. Org 6368 shares with pancuronium a very weak effect on both the muscarinic receptor and ganglionic transmission. Differences in the muscle relaxant profiles of Org 6368 and pancuronium are discussed.