Derivation

Tropacocaine is an alkaloid obtained from the leaves of a plant of the coca family, indigenous to Java, and has been isolated by Giesel. The hydrochlorate of tropacocaine was prepared by Lieberman, as the base of the product he obtained synthetically, which was not very soluble in water. Unlike cocaine solution, which deteriorates in a few days, the solution of the salt tropacocaine can be kept for several months without decomposition. Tropacocaine, by its chemical composition, belongs to the atropine group.

Physiological And Therapeutic Action

Tropacocaine is a local anaesthetic, and as indicated by a series of experiments made by Chadbourne, is about half as toxic as cocaine, and possesses the same local anaesthetic properties without the accidents of the latter agent.

No symptoms indicating the physiological action of tropacocaine followed its administration internally in the case of a dose varying from one-third to three-quarters of a grain ; and a submucous injection of nearly one-half grain in ten drops of water in many nervous and frightened persons, produced only a slight increase in the number of radial pulsations, without any changes in the arterial pressure. No bad symptoms apparently followed the hypodermic injection of three-quarters to one grain of tropacocaine even in nervous, anaemic and tuberculous patients, according to Pinet and Vian, although they observed, contrary to what occurs in cocaine, an increased activity in the peripheral circulation, the face exhibiting a characteristic rosy hue, and the extremities becoming warm. Their conclusion was that tropacocaine hydrochlorate possesses local anaesthetic properties anala-gous to cocaine. It is also claimed that the more concentrated the solution of this drug, the more rapid is its action. Its effect upon the nervous system, as well as upon the respiration, is directly opposite to what occurs in the intoxication by cocaine, as an equal part of cocaine has produced dangerous symptoms, and, on the contrary, neither respiration nor the nervous system appears to be influenced by doses of three-quarters of a grain of tropacocaine. And although its use may not be without danger, vet it is undoubtedly much less toxic than cocaine. But from the fact that its toxic action on the heart is very rapid when such does occur (although it lasts but ten minutes, while that from cocaine may last for hours), yet the use of tropacocaine requires caution. Prof. H.C.Wood states that this drug appears to have only a comparatively feeble influence upon the circulation, causing, however, when in sufficient amount, a steady fall in the arterial pressure. When applied to the eye, the anaesthesia is more prompt, and disappears more quickly than with cocaine, sensation being suspended in less than half a minute after the application of a three per cent. solution. Dr. Hugenschmidt claims that the advantages of tropacocaine over cocaine are:

1. Used in equal doses sufficient to produce local anaesthesia, the new drug is much less toxic than cocaine, and has a very slight action on the vital functions of the economy.

2. It produces a local anaesthesia more rapid and more pronounced than cocaine, and of at least as great a duration.

3. The solution of the salt being an antiseptic, as was pointed out by Chadbourne, can be kept for several months without deterioration, while, after a few days, a cocaine solution is worthless for injections.

Dental Uses

Tropacocaine is employed in dental practice as a local anaesthetic for the extraction of teeth, for the perforation of the alveolus, removing sequestrum, sensitive dentine, opening of abscesses, etc. Dr. Hugenschmidt regards two-thirds of one grain in fifteen drops of water as sufficient in ordinary cases. For difficult extractions, four-fifths of one grain, he asserts, will produce complete anaesthesia. The injections are made as with cocaine, but not suddenly, as at least one minute should be employed in injecting the dose, which, according to Dr. Hugenschmidt, is ten drops of the following solution: Tropacocaine hydrochlorate, 2 grains ; distilled water, 50 drops. M. S. - Gtt. x for one local anaesthesia. The tooth or root to be extracted, or region to be operated on, is surrounded by a series of injections of one or two drops of the above solution until ten drops have been injected. The dose of tropacocaine is gr. 1/3 to 2/3. Before injection the mouth should be made aseptic by washing it repeatedly with 3 per cent. solution of pyrozone, 10 per cent. solution of electrozone, or 3 per cent. solution of formaldehyde. The syringe should also be rendered aseptic by a 25 per cent. solution of phenol sodique, which will not injure the metallic parts. Care should be taken to confine the injections to the gum tissue, as serious emphysema may result from injections into the submucous tissue beneath the junction of the cheek and gum.