This section is from the book "Materia Medica Pharmacy, Pharmacology And Therapeutics", by W. Hale White. Also available from Amazon: Materia Medica Pharmacy, Pharmacology And Therapeutics..
The rhizome and roots of Gehemium sempervirens (Linne) Persoon (nat. ord. Loganiaceae).
Southern United States.
Cylindrical, long, or cut in sections, motly from 5 to 15 mm. and occasionally 3 cm. thick, the roots much thinner; externally light yellowish-brown, with purplish-brown, longitudinal lines; tough; fracture splintery; bark thin, with silky bast-fibres, closely adhering to the pale yellowish, porous wood, which has fine, medullary rays, and in the rhizome a thin pith; odor, aromatic, heavy; taste bitter.
The chief constituents are - (1) Gehemine, C54H69N4O12, a colorless, with difficulty crystallizable, bitter alkaloid, soluble in Alcohol and Ether, sparingly in water. (2) Gelseminine, a brown, amorphous, bitter alkaloid, very poisonous. (3) Geheminic Acid. (4) A volatile oil.
Dose, 5 to 10 gr.; .30 to .60 gm. Of Gelsemine hydrochlorate (not official), 1/60 to 1/20 gr.; .001 to .003 gm.
1. Extractum Gelsemii Fluidum. - Fluid Extract of Gelsemium. By maceration and percolation with Alcohol and evaporation.
Dose, 5 to 10 m.; .30 to .60 c.c.
2. Tinctura Gelsemii. - Tincture of Gelsemium. Gelsemium, 150; by maceration and percolation with Alcohol, to 1000.
Dose, 1/4 to 1 fl. dr.; 1. to 4. c.c
Gelsemium produces no effect on the stomach or intestines. Its powerful general physiological effects are due to the gelseminin'e in it.
Brain. - In poisoning by gelsemium consciousness is maintained till the end; the drug, therefore, has no power on the higher cerebral centres.
Spinal cord. - The most marked symptom produced by gelsemium is paralysis of all the muscles of the body; and by a series of experiments, like those used for strychnine, this can be shown to be due to depression of the activity of the anterior cornua of the spinal cord. This is said to be followed by a depression of the sensory part of the cord, with consequent anaesthesia. The motor nerves are quite unaffected till just before death, when the end-plates are paralyzed. The result of the action on the cord is that the patient may be unable to walk, or, if he can, the gait is staggering; his general sensibility is much impaired. Convulsions may be produced. The cause of these cannot be made out, for they appear to be neither cerebral, spinal, nor peripheral.
Eye. - Gelsemium soon causes disturbance of vision, then follows diplopia, due to paralysis of the ocular muscles, and from the same cause the upper lid drops. The pupil is dilated. All these symptoms are probably owing to the paralysis of the motor centres in the floor of the fourth ventricle and the aqueduct of Sylvius, for these are the continuation upwards of the anterior cornua.
Circulation. - The action of moderate doses is not marked. Toxic doses are powerfully depressant; the force and rate of the pulse and the blood-pressure fall. This is owing to a direct action on the ends of the vagus. How far these effects are due also to affection of the medullary and spinal centres is not known.
Respiration. - Soon after the administration of gelsemium the respiration becomes slower and more feeble; ultimately it stops, death taking place by asphyxia. This is due to paralysis of the respiratory centres in the cord and medulla. Before death the temperature falls, and the skin is bathed in a cold sweat.
Gelsemium was formerly given as a circulatory depressant, but it is not now used, as its other effects are so harmful. Nor is it any longer prescribed for convulsive diseases, as tetanus, whooping-cough, chorea, etc., as it was not found to do any good. It is often successfully used for neuralgia and migraine; how it acts is quite uncertain. A good combination for neuralgia and migraine is gelsemine hydrochlorate 1/200 gr. .0003 gm.jwith butyl chloral hydrate, 3 gr. .20 gm. made into a pill with mucilage, and given every two hours until pain is relieved. Sometimes it is employed to dilate the pupil and paralyze accommodation. It will do this when applied locally, for it is quickly absorbed from the eye. It has the advantage that its influence passes off rapidly. Discs of gelatin, each containing 1/500 gr. .00013 gm. gelsemine (not official), are made for application to the eye.