Abstract
Summary: . AH5183 (2‐(4‐phenyl piperidino) cyclohexanol) produced neuromuscular block of slow onset in rapidly stimulated nerve‐skeletal muscle preparations of the rat, chicken and cat. . The neuromuscular block was not antagonized by neostigmine, tetraethylammonium (TEA) or choline. The rate of onset of transmission failure was enhanced by factors which increase the release of acetylcholine. . It was concluded that the neuromuscular blocking activity was primarily pre‐junctional in origin, being due either to a non‐competitive action on the choline transport mechanism, or to an intracellular action on acetylcholine metabolism. . In high doses AH5183 possessed local anaesthetic activity, but this was considered insufficient to bring about the failure of neuromuscular transmission. . AH5183 also produced a block of sympathetically innervated preparations that was indistinguishable from that produced by an α‐adrenoceptor blocking drug.