Ganglion-blocking activity of bisquaternary ammonium salts derived from 3 ,12 -diamino-5 -cholane and 3 ,12 -diamino-24-nor-5 -cholane

The neuromuscular and autonomic blocking activities of pancuronium, Org NC 45, and other pancuronium analogues, in the cat

Twenty-six mono- or bis-quaternary salts of 3,17-dioxy-2 beta, 16 beta-dipiperidino-5 alpha-androstanes (including pancuronium) and one 17-desoxy congener were tested for neuromuscular blocking and autonomic blocking activities in the chloralose-anaesthetized cat. The 17 beta-acetoxy series, all the members of which contain an acetylcholine-like fragment in the steroidal D-ring, was most selective for effecting neuromuscular blockade. The salient member of this series is 3 alpha, 17 beta-diacetoxy-2 beta, 16 beta-dipiperidino-5 alpha-androstane 16 beta-N-monomethobromide (Org NC 45) which is highly selective in blocking neuromuscular transmission in that a dose approximately sixty times greater than the neuromuscular blocking dose was required to block responses to vagal stimulation. In contrast, in doses sufficient to produce neuromuscular block, pancuronium simultaneously blocked responses to vagal stimulation. Moreover, pancuronium and Org NC 45 exhibited the same order of neuromuscular blocking activity and therefore the latter potentially represents a useful addition to the armamentarium of neuromuscular blocking agents currently in clinical use.

Some actions of chandonium iodide, a new short-acting muscle relaxant, in anaesthetized cats and on isolated muscle preparations

1. The actions of the new skeletal muscle relaxant chandonium (HS310) on the cardiovascular, respiratory and skeletal muscle systems of the cat under chloralose anaesthesia and on chick and rat isolated skeletal muscle preparations have been described. 2. In the cat chandonium exhibited a potent, competitive, non-depolarizing neuromuscular blocking action that was rapid in onset and of short duration. It possessed a selective atropine-like action at the cardiac vagus neuro-effector junction but little or no ganglion blocking activity. Neither adrenergic neurone noralpha-adrenoceptor blocking properties were evident. 3. Unlike tubocurarine, chandonium was without effect on the airways system of the anaesthetized cat. 4. Chandonium possessed weak anticholinesterase action. It is conceivable that this effect may contribute to its short duration of action. 5. The results from these studies suggest that chandonium may have possible clinical applications as a short-acting muscle relaxant.

Neuromuscular and other blocking actions of a new series of mono and bisquaternary aza steroids

The effects of a newly-synthesized series of mono and bisquaternary aza steroids have been investigated in the anaesthetized cat. All the compounds have been tested for neuromuscular blocking, ganglion blocking and vagolytic activity. The monoquaternary compounds of the series were weak neuromuscular blocking agents, their main action being to produce ganglion blockade and a fall in blood pressure. Both the bisquaternary compounds of the series primarily exhibited neuromuscular blocking activity of short duration and rapid onset. 4-Methyl-17 β-dimethylamino-4-aza-5α-androstane dimethiodide (HS-467) was approximately equipotent with tubocurarine as a neuromuscular blocking agent, whereas 17a-methyl-3β-pyrrolidino-17a-aza-D-homo-5-androstene dimethiodide (HS-310, chandonium iodide) was 4–5 times more active. Both compounds exhibited extremely weak ganglion blocking activity. Structure-activity relations are discussed, and it is concluded that in this series two quaternary heads are necessary for optimal neuromuscular blocking activity. The possibility that in the bisquaternary compounds interonium distance, or stereochemical conformation may be the main factor in determining specific neuromuscular blocking activity is discussed.

Neuromuscular blocking and ganglion blocking activities of some acetylcholine antagonists in the cat

The potencies of tubocurarine, gallamine, pancuronium, benzoquinonium, hexamethonium and mecamylamine in blocking neuromuscular transmission in the soleus muscle, and in blocking contractions of the nictitating membrane evoked by preganglionic sympathetic stimulation have been compared in cats under chloralose anaesthesia. On a molar basis, pancuronium was about 8 times and benzoquinonium about 2·5 times more potent than tubocurarine in blocking the soleus muscle; gallamine was less than half as potent, mecamylamine about 128 times and hexamethonium about 380 times less potent. In blocking the superior cervical ganglion, mecamylamine was about 17 times more, tubocurarine was about 5 times more and pancuronium about twice as potent as hexamethonium. Benzoquinonium was about half as potent as hexamethonium, and gallamine about 5 times less potent. The results emphasize that the shorter distance between charged centres, as in hexamethonium, reduces affinity for muscle receptors but does not necessarily enhance affinity for ganglion receptors, and from the point of view of deductions concerning the configuration of the ganglionic receptor, the ganglion blocking potencies of some neuromuscular blocking drugs should be taken into account.