Apomorphine

Apomorphinae Hydrochloras.—Apomorphine hydrochlorate. The hydrochlorate of an artificial alkaloid obtained by the action of strong acids upon morphine contained in closed tubes and subjected to a somewhat elevated temperature. It is obtained also by the action of chloride of zinc in solution on morphine. It is a whitish powder, which becomes greenish by absorption of moisture. It is soluble in water, and it may, therefore, be administered in this menstruum. Dose, gr. 1/16 to gr. 1/8. If given hypodermatically, gr.1/16 is sufficient; if by the stomach, gr.1/8. As it undergoes important changes when in contact with water, the solution for hypodermatic use should be made when required, or at least should be frequently renewed.

Apocodeine

Apocodeinm Hydrochloras.—Apocodeine hydrochlorate. An artificial alkaloid obtained from codeine, as apomorphine is made from morphine. It has similar powers and properties to apomorphine, but it is somewhat less active as an emetic, while it is more useful as an expectorant. Apocodeine is given by the stomach or sub-cutaneously. The dose is gr. 1/12 to gr. 1/6.

Physiological Actions

Whether injected under the skin or taken into the stomach, apomorphine causes vomiting. The rate at which it moves to affect the stomach depends somewhat on the dose administered. From five to twenty minutes elapse after the hypodermatic injection before vomiting begins. The act of vomiting is preceded by very little nausea, the contents of the stomach are usually thoroughly evacuated, and the vomiting recurs a few times at intervals of a quarter to a half hour. In young subjects very considerable depression has been observed to be produced by it, and dangerous symptoms of cardiac paralysis have followed its emetic action in a few instances. These clinical facts seem to contradict the experimental observations of Siebert and Moerz, who have shown that apomorphine does not affect the blood-pressure, and that the pulse rises when emesis comes on, reaches its maximum during vomiting, and declines in the interval. The cardiac depression which has been observed, clinically, may have been the result of idiosyncrasy, yet we should not lose sight of the fact observed by Harnack, that in cold-blooded animals it may be produced experimentally.

Apomorphine causes at first increased rapidity of the respiration, afterward diminishes the force and depth of the movements, and finally arrests them. As this result occurs when the vagi are divided, the drug must necessarily first excite and afterward exhaust the irritability of the respiratory center. Apomorphine has no appreciable influence on the temperature.

As respects its impression on the nervous system, apomorphine is at first strongly excitant. Afterward it causes muscular tremblings, followed by paralysis and convulsions. The muscular irritability is impaired but not destroyed, and the functions of motor and sensory nerves remain intact; hence it may be concluded that the convulsant action of this agent is due to a direct impression on the spinal cord (the spasm-center).

Therapy

Apomorphine is indicated as an emetic when swallowing is difficult or impossible, and when very prompt action is necessary. As it produces vomiting by its spinal action, profound narcosis will prevent it, and hence, in narcotic poisoning, it may fail of effect unless administered before narcosis has supervened. It is a suitable emetic when it is desired to empty promptly an overloaded stomach. It is to be preferred to all emetics which must be introduced into the stomach, when this viscus is in a state of inflammation, for it is best given subcutaneously. Apomorphine has been administered as an emetic in suffocative catarrh, to empty mechanically the bronchial tubes, but it produced serious depression—a result which might have been a priori predicted, since this drug exerts a paralyzing action on the respiratory organs. It has also been given as an expectorant, but on insufficient data, for it does not seem to have an effect upon the vagi, and, as above stated, at first it excites the respiration movements, and afterward paralyzes them.

As compared with its congeners, morphine and codeine, it is more excitant than morphine and codeine, and without their hypnotic and anodyne properties. As respects its convulsant action in animals, it has close physiological relations to narcotine and thebaine. Some clinical experiences have shown (Riegel und Böhm) that apomorphine causes heaviness in the head, giddiness, drowsiness, yawning, mental hebetude, etc. The trials in which these results were noted were made with Merck's preparation of apomorphine.

Recent experiences have demonstrated that apomorphine has remarkable calmative and hypnotic effects in the excitement and wakefulness of alcoholism. For this purpose it is better given hypo-dermically, although good effects have been obtained by the stomachal administration. The dose by the former method is from 1/12 to 1/4 gr., and by the latter, 1/4 to 1/2 gr.

It has proved most successful in delirium tremens, inducing quiet and refreshing sleep, when the most noisy and threatening delirium had occurred. This agent is probably one of those most relied on to remove the desire for alcoholic drinks, and to quiet the restlessness and excitement which the absence of the stimulant sets up in those undergoing the so-called cure.