American Materia Medica, Therapeutics and Pharmacognosy

Gelsemium is quickly eliminated from the system, largely through the
kidneys, consequently the effects of single doses are quickly dissipated,
and medicinal doses must thus be given frequently, especially in
childhood, to insure good results. Single full doses should be given only
to adults.
The remedy can be given in single doses of from fifteen to twenty minims,
but any dose of three drops or more must be watched for physiological
effects, and diminished when these appear.
Physiological Action—Usually upon the administration of an overdose of
this agent there is at first some excitement, followed by depression of the
nervous system, with dizziness, amblyopia, double vision, dilated pupils,
exophthalmos, complete prostration, with drooping of the, upper eyelids
from paralysis of the levator palpebrae superioris and inability to keep the
jaw closed. The temperature is reduced, the force and frequency of the
pulse is lowered, with dyspnea, the breathing being accomplished with
much effort, and death usually results from paralysis of the respiratory
muscles, including the diaphragm. The influence appears to be exercised
upon the base of the brain, on the brain, on the splanchnic nerves and on
the spinal cord. It inhibits the nerve force of all the visceral organs and
relaxes the sphincters. Convulsions are one of the results of poisonous
doses in animals. In man, while there is loss of sensation and motion, the
patient is conscious of what is going on around him, unless the
symptoms are prolonged, when deficient oxygenation of the blood, with
accumulation of carbonic acid, will produce coma.
In experiments made upon pigeons the effects are very similar to those
resulting from destruction of a portion of the cerebellum. There are
irregular backward movements, tremblings, flutterings of the wings,
preceding complete paralysis.
Gelsemium in lethal doses paralyzes the nerves, both sensory and motor.
The motor nerves are first influenced, the paralysis of sensation more
slowly following. The writer observed a case of poisoning where the
patient had taken sixty minims of the fluid extract within forty-five
minutes. A sensation of general oppression occurred rather suddenly.
The patient rose to her feet, noticed that vision had failed almost
completely, walked two or three steps, then fell in a mass upon the floor
in a state of complete muscular relaxation. There was no alarm or fear, a
rather tranquil feeling mentally, and in this case there was no great
difficulty of breathing, although we have observed dyspnea from single
Ellingwood’s American Materia Medica, Therapeutics and Pharmacognosy - Page 225