This section is from the book "Materia Medica: Pharmacology: Therapeutics Prescription Writing For Students and Practitioners", by Walter A. Bastedo. Also available from Amazon: Materia Medica: Pharmacology: Therapeutics: Prescription Writing for Students and Practitioners.
The convulsion is at first tonic, that is, the contraction is continuous, making the muscle rigid; it then changes to clonic, i. e., rhythmic intermittent contraction; then it ceases. Before another convulsion sets in there is a moment of great muscular relaxation, with complete prostration and soreness of the muscles. If the poisoning is severe, the convulsions follow in rapid succession, being brought on by the slightest stimulus - the slamming of a door, a touch, a flash of light, a puff of air, the moving of a limb, talking or any voluntary effort. In mammals, after a few convulsions,. there is complete exhaustion with collapse. Death takes place from asphyxia, due either to exhaustion of the respiratory center or to continuous spasm of the respiratory muscles. The heart may keep on beating for some time after respiration has ceased. It is put under great strain by the repeated convulsions. Death usually takes place inside of two hours.
One-twelfth grain (0.005 gm.) of strychnine sulphate in a woman has given beginning toxic symptoms; 4/5 grain (0.05 gm.) in a day has been well borne by patients who had become tolerant to the drug. Shoemaker reports recovery in three hours of a student who had taken thirty 1/16 grain (0.004 gm.) pills of the sulphate. Hewlett reports restoration in a man after 15 grains (0.972 gm.). He recovered over 1 3/5 grains (0.11 gm.) from the urine and 4 1/2 grains (0.3 gm.) from the first stomach washing. A dose of 1 150 grain (0.0004 gm.) per kilo intravenously or intramuscularly is invariably fatal to dogs (Githens and Meltzer).
If the drug has been swallowed, but symptoms of poisoning have not yet come on, the stomach should be thoroughly lavaged, and tannic acid or even tea administered to form the rather insoluble strychnine tannate, and thus retard absorption. The tannate formed must be washed out at once, as it is slowly absorbed. If tea is employed, immediate lavage is particularly necessary, lest the caffeine of the tea be absorbed and increase the poisonous effect. Most of the caffeine may be got rid of by steeping the tea in boiling water for three minutes, discarding this water, and then steeping the residue to extract the tannic acid (Hatcher). If the convulsions have begun, lavage may also be indicated; but usually, because of the rapid absorption of the drug, it is useless at this stage. Before a stomach-tube can be inserted it may be necessary to administer ether.
For quick action, chloroform or ether by inhalation. Ether is said to have proved an effective antidote in dogs. Hewlett kept his patient continuously under ether for about six hours and so abolished the convulsions. But general anesthesia must be used with caution; for both chloroform and ether tend to increase the already serious muscular relaxation between the convulsions, and chloroform depresses the respiratory center. Failure of this center in strychnine poisoning threatens at any moment. For prolonged effect, bromides in large dose, \ ounce (15 gm.) by mouth or rectum. These are directly antagonistic to strychnine in their action upon the cord. Paraldehyde does not depress the respiratory center, and may be of use in some cases. (Morphine should not be employed, for it not only depresses the respiratory center, but also fails to antagonize the strychnine effect upon the cord. Chloral hydrate is sometimes used; but in safe amounts has too little action upon the cord, and, like chloroform, has the disadvantage of being very depressing to the respiratory center.)
Spinal anesthesia with cocaine has been effective in protecting the trunk and hind-limbs of animals from the convulsions, but it does not protect the fore-limbs and head, and does not prevent the great relaxation of the voluntary muscles, even in the hind-limbs. Magnesium sulphate intraspinally or intravenously would be better.
The oxygen acts not only to furnish respiratory oxygen, which is deficient because of the interference with respiration and of muscular activity, but also to increase the rapidity of oxidation of the strychnine in the body. Gies and Meltzer claim that the rhythmic motions of artificial respiration tend to delay the onset of convulsions.
To remove and so prevent reabsorption of the strychnine passed out by the kidneys.
Delbert found that if he followed the injection of a lethal dose of strychnine into a dog by an intravenous infusion of normal saline, free diuresis promptly resulted and no signs of strychnine poisoning were manifest. Hatcher and Smith found that diuresis hastened the elimination of the drug, but never sufficiently to save an animal given 20 per cent. above the average lethal dose. Githens and Meltzer (1912) recommend the combination of ether anesthesia, intratracheal insufflation, and intravenous administration of Ringer's solution.
Strychnine and nux vomica preparations are extensively employed as tonics in conditions of debility with loss of appetite, and in convalescence from severe illnesses. In these conditions the effect on appetite is of value as well as that on tone. For a more marked action on the reflexes, they are given in atonic conditions of the abdominal viscera, as of stomach, intestines, bladder, and uterus, in the relaxed atonic types of chronic bronchitis, in conditions of weak, ineffective cough, as in severe tuberculosis with much bronchial secretion, and in acute and chronic alcoholism. "Strychnine is to asthenia what morphine is to pain" (Hartenberg).
Further, in serious acute diseases like pneumonia, where there is much prostration, and in narcotic poisoning, as from alcohol, ether, or chloral hydrate, large doses may be administered for respiratory and spinal stimulation. It is to be noted that while strychnine is good in chloral poisoning, chloral hydrate is not good in strychnine poisoning.