Some pharmacological properties of o-methyl-alpha-propylaminopropioananilide, a new local anaesthetic.

The anaesthetic action of o-methyl-alpha-propylaminopropionanilide (L 67, Astra) has been studied and compared with lignocaine in different in vitro and in vivo tests. Procaine and amethocaine (tetracaine) were also included in several of the comparisons. In nerve block on the isolated frog sciatic nerve L 67 is somewhat less effective than lignocaine. In all in vivo conditions, however, L 67 is quite comparable to lignocaine as to duration, latency and frequency of anaesthesia. As a spinal anaesthetic in rabbits 2 to 4% solutions of L 67 give a longer duration of anaesthesia than lignocaine. Toxicity in mice and rabbits and respiratory and circulatory effects in cats have also been evaluated. L 67 is almost twice as well tolerated as lignocaine. It is concluded that L 67 may prove to be a useful anaesthetic in certain clinical applications.