The root of Gelsemium sempervirens, of the Southern United States. The alkaloid gelsemium and gelse-minic acid are the important constituents.
The smallest active quantity ( v.-xv.) causes a languid feeling, with slight reduction of the strength and frequency of the pulse. If the amount be increased, pain over the eyes, some disturbance of vision, and dizziness result, with increased perspiration. It has a peculiar nervous effect 011 some people, making them cry without knowing why.
Gelsemium relieves obscure pains and is used in a great many quack-cures for rheumatism, which are especially dangerous because of this drug and the ignorance of the laity in regard to it.
Poisonous doses (ʒ i. of the fluidextract) produce, in addition to these symptoms, great muscular weakness, affecting especially the flexors of the arms.
The gait also is affected, and becomes staggering. The jaw drops, and articulation fails. There is marked effect on the sight: double vision, partial or complete blindness may develop; sometimes a squint is produced; the eyelid droops; the pupil dilates.
There is profuse perspiration, cold surface and subnormal temperature, and a condition of general anaesthesia. The pulse is thready and feeble, and death finally results from paralysis of the respiratory muscles. Consciousness remains until carbonic - acid narcosis begins as the result of asphyxia.
Gelsemium is rapidly diffused, and the effects appear within half an hour, and, after medicinal doses, disappear within two or three hours.
Death, when it occurs, may do so in a few hours, and has been known to result from taking one sixth of a grain.
Poisonous symptoms are treated by emetics, alcoholic stimulants, external heat, electricity, and artificial respiration, if necessary.
Average dose, 1/2-0.03 mil.
Strength 10%. Average dose, iv.-0.25 mil.