CHAPTER XI
SEDATIVE POISONS
Cardiac
DIGITALIS
The common foxglove, Digitalis purpurea, (N.O. Scrophulariaceæ), grows wild in the hedges in the South of England. All parts of the plant are poisonous, from the presence of a glucoside digitalin, and in addition it also contains the glucosides digitoxin, digitonin, and digitalein; according to Kopp, digitoxin is six to ten times more toxic than digitalin.
Symptoms.—Nausea, salivation, vomiting, purging, and severe abdominal pains are first noticed. The patient then complains of pain in the head, giddiness, and a gradual loss of sight. The eyes protrude, the pupils are dilated and insensible to light, and the sclerotics, according to Tardieu, are of a characteristic blue colour; the pulse weak, slow (forty in the minute) and jerky, sometimes intermittent. The surface of the body is cold, and bathed in perspiration. An aggravation in the symptoms takes place whenever the patient attempts to leave the recumbent position; hence, in all cases of poisoning, and in those where the therapeutical action of the drug is sought, the patient should be warned of the danger of leaving the recumbent posture. A marked depression in the action of the heart is a characteristic effect of this poison. The effect on the heart may be divided into three stages: (1) diminution in the frequency of the pulse, and rise of arterial pressure; (2) both of these become abnormally low; (3) frequency of pulse abnormally high, arterial pressure abnormally low. Convulsions have sometimes been noticed, and syncope and stupor are not uncommon.
Post-mortem Appearances.—Congestion of the brain and its membranes, and some inflammatory redness of the mucous membrane of the stomach. The blood is fluid.
Fatal Dose.—Uncertain. Large doses of the infusion and tincture have been given without any untoward results. Thirty-eight grains of the powdered leaves, and nine drachms of the tincture, have proved fatal. One-quarter to half a grain of digitalin might prove fatal to an adult.
Fatal Period.—From three-quarters of an hour to twenty-four hours.
Chemical Analysis.—If the leaves in an infusion be taken, these must be sought for and examined. The glucoside may be extracted by first removing the impurities by means of petroleum ether, then acidifying with acetic acid and extracting with chloroform.