The drawbacks in the use of cocaine are:

1. Its general poisonous action.

2. The frequency of undesirable idiosyncrasy to it.

3. Its decomposition at boiling temperature, which prevents effective sterilization.

4. Its poor keeping qualities in solution.

5. Its tendency to vicious habit formation.

Because of these alleged drawbacks to the use of cocaine, a number of other local anesthetics have been brought forward as cocaine substitutes. Of these the following are closely related chemically, and are employed in the same strength as cocaine:

Eucaine, beta-eucaine chloride or lactate, trimethyl-benzoxy-piperidine, which is irritant locally, but may be boiled without harm, does not constrict the arterioles, and has very slight effect upon the pupil and accommodation. The chloride is soluble in 30 parts of water, and the lactate in 20 parts.

Stovaine, di-methyl-amino-benzoyl pentanol chloride, which is soluble in its own weight of water, is more irritant locally, dilates the arterioles on local application, and in spinal analgesia induces muscular relaxation. It is too irritant for use in the eye, and has shown a greater tendency than cocaine to produce local gangrene.

Alypine, benzoyl-tetramethyl-diamino-ethyl-isopropylic alcohol chloride, readily soluble in water. Its solutions will not stand boiling. It dilates the arterioles, and has no effect on either pupil or intra-ocular tension.

Novocaine, para-amino-benzoyl-diethyl-amino-ethanol chloride, soluble in its own weight of water, not decomposed by boiling, and without effect upon the arterioles. Schley found that large doses administered to guinea-pigs produced practically the same poisonous symptoms as cocaine, but it required about six times as much of the novocaine. As it is not absorbed readily by mucous membranes or the eye, it must be used hypodermat-ically. To prevent shock, Crile uses a solution of 1: 400 to anesthetize the field of operation in advance of cutting.

Hatcher and Eggleston find the symptoms less persistent than those from cocaine; also that slow continuous intravenous injections of large amounts fail to produce lasting effects. Toxic amounts quickly administered cause immediate stoppage of heart and respiration.

Tropacocaine, the benzoyl ester of pseudo-tropine chloride, is more irritant locally, and does not dilate the pupil or affect the arterioles. Its solutions can be boiled.

These drugs are all chemically related to cocaine. They are found to be less irritating to the tissues and less destructive if dissolved in normal saline rather than pure water. They are all prompt in producing anesthesia, and their effects last only from fifteen minutes to half an hour; but they all maintain anesthesia for a much longer period if used with a small amount of epinephrine, the anesthesia being a little slower in coming on. The epinephrine acts by constricting the arterioles so that the drug is not carried away so rapidly by the blood-stream; a further advantage is that, by the blanched area, it shows exactly where the drug has been injected.