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DIGITALIS. ; ;
383
DIGITALIS.
Derivation.—Digitalis is obtained from the leaves of the Digi-
talis purpurea^ or Foxglove. Digitoxin and Digitalin are the tw^o
most active principles, but neither will take the place of digitalis
in medicinal use.
Medical Properties and Physiological Action.—As digitalis irri-
tates mucous membranes which are wanting in tone, it should
not be internally given in gastritis, etc. Its action is only mani-
fested on the nerves when toxic doses are administered. Its
action is chiefly manifested upon the circulatory system, as it
increases the pulse-force and arterial pressure, and size of the
pulse-wave, and slows the pulse, when moderate doses are given.
When full medicinal doses are employed, or when poisonous
doses are injected, the action of the heart becomes very irregular,
and dicrotic, and, according to Hare, it is not due to weakness,
for the cardiac beats when they occur, are in themselves more
forcible than in health. Digitalis only effects respiration when
poisonous doses are given, when it is slowed.
The medicinal dose has little or no effect upon the normal
temperature of the body ; it has no effect on the kidney struc-
ture, but sometimes causes nausea and indigestion by irritating
the stomach.
Digitalis is a cardiac stimulant, and not a depressant.
Therapeutic Uses.—It is employed in all cardiac diseases, and
is beneficial when the heart is irritable and palpitation is present,
and the cause is not due to indigestion. It is also employed in
cardiac weakness from collapse, and is particularly serviceable in
aconite poisoning. To counteract its slow action, it should be
preceded by ammonia and alcohol in urgent cases. It is also
useful as a diuretic in congested kidney affections, and in cardiac
dilatation and asthenia. Tannic acid is the chemical antidote
also the stomach-pump, and emetics if the heart is not affected
external heat about abdomen, and the maintainance of a hori-
zontal position for several days after the active poisonous symp-
toms are manifested. Tincture of aconite is the physiological
antidote. In all cases it is necessary that the slow absorption
and elimination of digitalis should be remembered. Hypodermic