Abstract

Apothesine is more toxic, as determined by animal experimentation, than procain, novocain or neocain.

Procain is identical in toxicity with novocain (German) and neocain (French), as determined by animal experimentation and clinical usage. It is equal to novocain and neocain in local and regional anesthesia.

Animal experimentation indicates that, during fanwise injections into the tissues, there is little danger from injections into the systemic veins, although the far smaller lethal dose of this method should be kept in mind.

Intra-arterial injections are less toxic than intravenous with the exception of those distributing to the vital nerve centers. The smallest fatal intravascular dose was obtained in injecting the common carotid artery. Were it possible to inject directly into the vertebral or internal carotid arteries it is reasonable to suppose that the lethal dose would be far smaller.

In cases of sudden collapse in operations on the throat and neck under local anesthesia, the sudden severe toxic manifestations probably result from an injection directly into the internal carotid or vertebral arteries.

A fixed maximal dosage of novocain is impractical because of the many factors influencing it. By observing precautions, very large doses may be administered safely. Careless use and indifferent dosage must be cautioned against although a solution of procain-adrenalin sufficient for the proposed operative procedure may be regarded as practically safe if properly injected. Our experiences in nearly 4000 surgical cases indicate that there is a sufficient margin of safety when from 1.5 to 2 gm. of procain in a 0.5 per cent solution is injected in terminal infiltration or field block, and when not more than 1 gm, in a 1 per cent solution is injected in nerve block, 10 minims of 1:1000 adrenalin being added to 100 cc. of solution in all cases.