|
|
Practical ecological knowledge for the temperate reader. |
Family: Plantaginaceae (Mare's-tail family)(Previously in Scrophulariaceae)
"Digitalis purpurea is a BIENNIAL growing to 1.2 m (4ft) by 0.6 m (2ft in) at a medium rate.
It is not frost tender. It is in flower from Jun to September, and the seeds ripen from Aug to October. The flowers are hermaphrodite (have both male and female organs) and are pollinated by Bees.It is noted for attracting wildlife." [PFAF]
"Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: acid, neutral and basic (alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers dry or moist soil."[PFAF]
Origin Status:
Exotic [E-flora]
General:
Robust usually biennial herb from fibrous roots; stems erect, 0.5-1.5 m tall, unbranched, densely grey-hairy and becoming glandular upward. [IFBC-E-flora]
Leaves:
Alternate, egg-shaped to lanceolate, 10-40 cm long, coarsely toothed, green and soft-hairy above, grey-woolly beneath, narrowed to the winged stalk, biggest and most numerous at the base in a rosette, reduced upward. [IFBC-E-flora]
Flowers:
Inflorescence a long, narrow, leafy-bracted, 1-sided, terminal raceme of numerous stalked, nodding flowers, the stalks 5-20 mm long; corollas gaping-tubular, 4-6 cm long, weakly 2-lipped, shortly 5-lobed, the lower 3 lobes fused into the longer, more prominent of the 2 lips, pink-purple with deeper purple spots on inside of lower lip, the lips fringed with hairs, sparsely long-hairy in the throat; calyces deeply 5-lobed, the lobes somewhat leaflike, lance-egg-shaped, 1-1.8 cm long; stigmas 2-lobed; stamens 4. [IFBC-E-flora]
Fruits:
Capsules, egg-shaped, about 12 mm long; seeds numerous, small, about 0.5 mm long. [IFBC-E-flora]
Characteristics:
The plant is very poisonous; it tastes hotbitter with a slightly unpleasant odor.[PDR]
Habitat / Range
Moist to mesic roadsides, fields, clearings and forest edges in the lowland zone; common in SW BC, infrequent in the Queen Charlotte Islands; introduced from Europe. [IFBC-E-flora]
"Acid soils in woods, heaths, mountain grasslands etc[9, 17]. Western Europe, including Britain, from Norway to Spain and Sardinia." [PFAF]
Additional Notes
"Foxgloves are native to Europe but have escaped from gardens to become well established in coastal British Columbia, particularly along roadsides and in forest clearings. Although magenta-flowered foxgloves are most common, many populations, even small ones, are polymorphic for flower colour. Flowers may be dark magenta, light magenta, or white, and the spots on the flowers may be purplish or yellowish to light brown. The genetics of flower and spot colour were worked out in Britain soon after the science of genetics was discovered in 1900, and the results were published in 1910. Three different genes were involved. One, M, produces the magenta pigment, an anthocyanin, and results in magenta flowers with purple spots. The homozygous recessive, mm has white flowers with yellowish or brownish spots. Its flowers have no anthocyanin pigment. A separate dominant gene, D, darkens the pigment, resulting in dark magenta flowers. So plants with a dominant M allele, for pigment, are dark magenta if they also have a D allele and are light magenta if they are homozygous recessive (dd) for the D gene. The D allele therefore enhances the expression of the M allele. It has no effect on mm plants, which have no anthocyanin pigment in their flowers. In addition, a separate dominant white gene exists. A dominant W allele produces white flowers, even if the plant also has the M allele for magenta pigment. (The recessive allele does not have this effect). A plant that is homozygous mm is already white flowered, so the W allele has no effect in this case. A plant with a W allele is white flowered, so the D allele has no effect on a plant with a W allele. Although the W allele prevents the expression of M, the W allele does not effect the colour of the spots. Thus, a plant with the W allele and the M allele has white flowers with purple spots, and a plant with the W allele that is also homozygous mm has yellow to brownish spots, just like the wwmm plant, which produces no anthocyanin pigment anywhere on the flower."
Source: Extracted with permission from Griffiths and Ganders 1983, Wildflower Genetics: A Field Guide for British Columbia and the Pacific Northwest. [E-flora]
Precautions and Adverse Reactions
General: Because of the narrow therapeutic range of digitalis
glycosides, a certain percentage of patients may experience
side effects immediately upon administration of therapeutic
dosages: hypertonia in gastrointestinal area, loss of appetite,
vomiting, diarrhea and headache.
Drug Interactions: The simultaneous administration of
arrhythmogenic substances (sympathomimetics, methylxanthines, phosphodiesterase inhibitors, quinidine) increases the
risks of cardiac arrhythmias.[PDR]
Overdosage
With overdosage, in addition to the already-mentioned
symptoms, the following can also occur:
Heart: cardiac rhythm disorders, all the way up to lifethreatening ventricular tachycardia, atrial tachycardia with
atrioventricular block
Central nervous system: stupor, visual disorders, depression,
confused states, hallucinations, psychoses
Lethal dosages lead to heart failure or asphyxiation. Administration over extended periods leads in rare cases to
gynecomastia. Because of the difficulties in standardizing
the drug, the administration of pure glycosides is to be
preferred (digitoxin).
The first measures to be taken in case of poisoning are
gastric lavage and activated charcoal instillation. All other measures proceed according to the symptoms. For loss of
potassium, careful replenishment is necessary. For ectopic
irritation build-up in the ventricle, administration of phenytoin as an antiarrhythmatic is recommended. Lidocaine
should be used in cases of ventricular extrasystole, and for
partial atrioventricular block, atropine is recommended. The
prophylactic installation of a pacemaker is often necessary.
For elimination of the glycosides hemoperfusion is possible,
the administration of cholestyramine for interrrupting the
enterohepatic circulation and/or the application of digitoxin
antibodies (antigen-binding fragments, digitalis antidote
{Boehringer Mannheim} , is very likely only fully effective
with digitoxin poisoning).
The drugs and pure glycosides should be administered in the
following situations (among others): atrioventricular block of
the 2nd and 3rd degree, hypercalcaemia, hypocalcaemia,
hypertrophic cardiomyopathy, carotid sinus syndrome, ventricular tachycardia, thoracic aortic aneurysm, WPW-syndrome.[PDR]
Once digitalis toxicity is diagnosed, digitalis and diuretic use should be discontinued.[PDBHM]
| Ethnobotanical Uses [DukePhyto] | ||
Asthma Krochmal;
Bactericide* Eb31: 35; | Fever Krochmal; | Renitis Woi.3; Sedative Steinmetz; Stimulant Steinmetz; Stimulant(Cardio) Eb33: 189, Singh; Tonic Eb33: 189, Singh, Steinmetz; Tumor(Abdomen) Hartwell |
Various Other Uses
Digitalis purpurea, foxglove
History
1775: William Withering, a British physician with a strong interest in
botany, introduces the drug digitalis (Foxglove Digitalis purpurea) into common medical practice for the treatment of
dropsy. Dropsy is a now-obsolete term for edema (fluid retention or swelling) due to heart failure.[UXL]
Lore
"The Irish also used it as an effective charm against
witchcraft. The patient was rubbed all over with it –
a dangerous practice, and the patient may die of it,
especially if tied naked to a stake, as was the custom
once (Wilde. 1890).
.... The dried leaves are the source of a very potent
drug that has the effect of reducing the frequency
and force of the heart action, so it is given in special
cases as a sedative, especially in heart disease. It was
Dr William Withering (1741-1799), from Wellington,
Shropshire, who first introduced digitalin into general medical practice. He published “an account of
the Foxglove and some of its medical uses” in 1788.
It is said he got his information from a witch. But this
is indeed a dangerous plant, which animals always
avoid. All parts are poisonous, but especially the
seeds. The leaves are more active before than after
flowering (Long. 1924). There was another use of the
toxic principle; that was in what the Americans call a
“chemical jury”. In other words it was used in ordeal
trials to test guilt or innocence – if he survived he was
innocent! (Thomson. 1976).
Gypsies use an ointment made from the fresh leaves
to cure eczema (Vesey- Fitzgerald), and in early times
the leaves were used mainly as an external application
for wounds and ulcers in the legs (Clair), for the toxic
potentialities were recognized very well early on. The
gypsy usage for ulcers was certainly known very
early, for in the Anglo-Saxon version of Dioscorides
(in Cockayne’s translation) we have “For inflammatory sores, take leaves …, work to a poultice, lay to the
sore”, and also “for a pimply body, take this same
wort and fine flour, work to a poultice, lay it to the
sore”. Much later, there are records from the Highlands for this use of the leaves on boils, and also on
bruises (Grant), or to cure erysipelas (Polson. 1926),
while on Skye a plaster made from them used to be
applied to remove pains that follow fever (Martin).
Along with barley meal and some other herbs, it
was included in an Irish preparation to treat epilepsy
(Logan), but what herb was not tried at some time or
other? As has been said (Thomson), desperate conditions demand desperate remedies! It must have been
a quite dangerous practice, but there are other records
of foxglove leaf infusions being taken. Gypsies use
a very weak infusion of the dried leaves for fevers
(Vesey-Fitzgerald), and foxglove tea was apparently
a standard domestic remedy for dropsy (Beith). Irish
people used to make a tincture for it with gin, and
then use a very small quantity on loaf sugar (Egan).
But given the known effect on the heart, there should
be no surprise at that. But using the leaf infusion as an
emetic, as was done in Ireland (Logan) is another matter.
Other Irish uses, for lumbago (Ô’Súilleabháin), or
for hydrophobia (Wood-Martin), for example, did not
need internal consumption. But there is another case
of an infusion taken internally; according to the Times
Telescope, 1822, “the women of the poorer class in
Derbyshire used to indulge in copious draughts of
foxglove tea, as a cheap means of obtaining the pleasures of intoxication”. Actually the practice was far
from being confined to Derbyshire.[DPL Watts]
Gender: Feminine
Planet: Venus
Element: Water
Powers: Protection
Magical Uses: Grown in the garden it protects it, as well as the home. In the past,
housewives in Wales used the leaves of the
foxglove to make a black dye, which they
used to paint crossed lines on their cottage's stone floors. This was done to keep
evil from entering the house.
Foxglove is poisonous; do not take
internally.[EMH Cunningham]
Pharmacology
| Activities (Digitalis)[HMH Duke] | ||
|
|
|
Digitalis also acts as a diuretic. In Withering’s time, it became a popular treatment for dropsy (DROP-see), an old-fashioned term for EDEMA. People with edema often have swollen feet, ankles, and lower legs due to water buildup in their tissues. Fluid retention in the tissues of the body can be very dangerous. It is frequently related to congestive heart failure, which can be deadly. As of 2005, digitalis-type drugs were still being used in the treatment of heart failure. By strengthening the contractions of the heart muscle, digitalis helps pump excess fluids throughout the body. When the heart works more efficiently, fluids are less likely to pool, or accumulate, in the feet and legs.[UXL]
Digitalin
Standard granule—Gr. 1-67, gm. .001. [Shaller]
Active Principles. The so-called active medicinal principles consist of a
number of glucosides: Digitalin, digitalein, digitonin, digitin and
digitoxin. Unfortunately, great confusion exists regarding these
preparations, which has been fostered by pharmacopoeial errors. Thus
the digitalin of Homolle and Quevenne, recognized by French authority,
is an amorphous, yellowishwhite powder, inodorous, intensely bitter to
taste, extremely irritating to the nostrils, and highly poisonous; it is
sometimes found as small scales. It is chemically a mixture of the digitalin
of the German pharmacopoeia and the digitoxin of Schmiedeberg.
Another form that has the sanction also of the French Codex is digitaline
(mark the final e) cristallisee, or the digitalein of Nativelle, and appears as
white, crystalline tufts or needles, and consists almost wholly of
Schmiedeberg's digitoxin. It is very bitter to taste, slowly eliminated and
consequently cumulative in action, and should be dispensed only when
"crystallized digitalin" is ordered. Both the foregoing are insoluble in
water or ether, but the crystallized form yields readily to chloroform and
rectified spirit. [Shaller]
Digitalis should not be given simply because valvular lesions are present.
There must be diminished blood-pressure and dilated arterioles, feeble
cardiac action, retarded flow of blood which produces venous
congestion, scanty secretion of urine, oedema and dyspnea. The
heartaction must be enfeebled and rapid. If it is irregular or intermittent
it is no contraindication, only that it beat frequently or feebly.
Digitalis is a much abused remedy. It is a powerful vasoconstrictor and an inhibitor of the heart-action, and because it is given in cases which
neither require an inhibitory action of the heart nor a contraction of the
arterioles, it necessarily does harm, perhaps produces death, and the
remedy is credited with being uncertain in its action.
A good strong pulse, with normal amount of urine excreted,
contraindicates its use, and if it were given where such conditions exist
the pulse would beat slower and harder and the quantity of urine would
be diminished. Digitalis should be confined to the treatment of enfeebled
conditions of the heart and blood-veins with disturbed circulation of the
blood. Digitalis is a diuretic only when the arterial capillaries are so
dilated as to lessen the blood-pressure in the malpighian bodies so that
the water cannot be forced through them. It is hardly probable that
digitalis can have diuretic effects without first increasing blood-pressure. [Shaller]
Digitalis may sometimes cause sudden death in such cases and is not therefore a safe remedy to give in large doses frequently repeated to such patients. Caution should always be used. Strychnine is preferable and is freer from danger, and one need not fear that one's patient may die suddenly and rather unexpectedly as is often the case when digitalis is given.. [Shaller]
CUMULATIVE ACTION
There is no doubt that sudden deaths occur more frequently while
digitalis is being administered than from any other medicine. As some
one has said, because this remedy is used to treat diseases of the heart
where sudden deaths are frequent, nothing much is thought of these
sudden deaths, and the remedy, least of all, suspected. Yet, the fact
remains that digitalis is the direct cause.
It may be difficult to satisfactorily explain how death occurs. Repeated
doses of medicines are not absorbed into the blood, accumulating
without producing any effect. Then after several days, all of this
accumulated medicine does suddenly let loose all of its energy, as by
explosion, causing death; just as if all the medicine which had been given
for days in divided doses should have been given at one dose and
quickly absorbed. The probabilities are, that it is a matter of cumulative
doses.[Shaller]
All medicines as soon as they enter the body also begin to leave it. It is
very well known that many medicines may be detected in the urine
within five minutes after their administration. Also when single doses of
some medicines are given, their presence can be demonstrated in the
urine for several days thereafter. While there may be some
decomposition of some of the alkaloids or other active principles, yet,
whether taken in their pure isolated state as digitalin, or if the digitalis
leaves are taken, the result is the same, the kidneys eliminate the
alkaloids or glucosides. The digestive system, by its chemistry and
solvent powers separates the active medicinal principles and other
matters from the insoluble.
The most powerful of the active principles of digitalis is digitoxin. It is
more slowly eliminated from the blood than are the others. The
prolonged action of digitalis depends altogether upon the slowness with
which its active principles are eliminated by the kidneys. When poisoning
does occur from frequently-repeated doses, the kidneys have not had
sufficient time to remove the medicine from the blood. There is therefore
an accumulation in the blood, which may increase to such an extent as to
finally cause death. It is simply over-dosing, caused by giving the
medicine too frequently without allowing time for its elimination. There
are many physicians who only give two doses of digitalis daily. This is
probably the correct method to prevent accumulation of the active
principles in the blood when large doses are given. The frequent
repetition of small doses of digitalin, as is customary with those who
practise dosimetry, does not seem to be accompanied by the same danger
as when cruder preparations are given. Possibly digitalin is not as potent
as digitalis. The latter may contain more of the poison, digitoxin.[Shaller]
One point should not be lost sight of during a course of digitalis
treatment:
If a patient is sick enough to be treated with digitalis, particularly if the
patient is aged or the pulse very feeble, he is sick enough to be in bed
and kept there in a persistent recumbent position until digitalis has
accomplished its work. Why? Because such patients are particularly
benefited by the recumbent position. It of itself will lower the rapidity of
the heart-action by fifteen or more beats.
The action of digitalis should be more carefully watched than that of
opiates because it will kill quicker. In such cases, everything seems to be
going along nicely, when the patient rises from his bed and falls over
dead. Died of heart disease? No. Died of digitalis poisoning. This is
likely to be so in treating typhoid fever of pneumonia with digitalis.
There may be two ways of explaining such results. Digitalis has probably
reduced the pulsations below the normal. The heart contracts with
extraordinary vigor. On suddenly assuming the erect position more force
is needed and the heart must beat with more vigor and, being in a state of tonic activity, its systolic action is so great that it remains in the
condition of tonic contraction or systole, and the patient dies.
On the other hand, when too much digitalis has been taken, it loses its
stimulating action and becomes. a paralyzant; when extra effort is made
as by standing, the arterioles dilate from weight of blood, the heartaction becomes very rapid and embarrassed and, because of the
gravitation of blood to the extremities, the brain centers become anemic
and fatal syncope results.
It took Koppe four days to recover from the effects of a single dose of 1-
33 gr. digitalin.
Give digitalis to feeble patients while in bed until the heart beats
normally and the secretion of urine is increased. This will require five or
six days.
Then stop giving the drug, but still keep the patient in bed for several
days and keep him on 1-30 gr. doses of strychnine every four hours. It is
never safe to give digitalis when the number of heart-beats is normal,
and surely not when it is below normal. In those cases where in the
recumbent or sitting position the number of pulsations is normal, but in
which on standing or upon slight exertion it increases thirty or more
beats, digitalis must be very cautiously used. Strychnine, apocynin and
cactin are better remedies and are free from danger.
In the treatment of post-partum hemorrhage, digitalis has frequently
been used with success. As it acts chiefly through the vasomotor
constrictions in reducing the caliber of the arterial capillaries by causing
contraction of the involuntary muscular fibers, its beneficial effects can be
readily explained. In hemorrhages of all kinds, where feeble heart-action
and diminished bloodpressure are prominent, digitalis is indicated. Dose
dram ij of the infusion or two to four granules of digitalin every two
hours for three doses, after which the remedy must be stopped. Digitalis
is also highly recommended in the treatment of spermatorrhea. Similar
conditions which guide its use in other diseases also answer here, viz.,
relaxation of the vascular system, evidenced by enlarged veins, easily induced sexual excitement with its accompanying congestion. The greater
the extent of self-abuse, the more frequent the indulgence in sexual
intercourse, particularly to excess, the more readily is venous congestion
of the genital apparatus produced. In such cases the most insignificant
and trivial thought or act produces an erection. This does not represent
sexual vigor, but sexual weakness. The genital vasomotor centers are
congested and become extremely sensitive to the slightest irritation.
Excessive irritation causes loss of their muscular toning property which
gives way to relaxation. This relaxed condition of the genital organs calls
for the use of digitalis. The general circulatory system, in fact the entire
body, is relaxed and toneless. Improve the circulation by digitalis and
small doses of strychnine. Overcome the extreme sensitiveness and the
exaggerated irritability of the vasomotor and genital centers by cicutine.
If "nervousness" is marked it is best to begin treatment with cicutine until
emissions are controlled, then follow it with strychnine and digitalis.
Remember always that when the pulse is restored to the normal number
of beats, digitalis should be withdrawn and strychnine given in its stead.
Digitalis is a remedy of greatest therapeutic value. It is the most
important medicine used in the treatment of heart-diseases, particularly
when accompanied by dropsy. No other remedy can approach it in
regard to usefulness. All other heart remedies are compared with it, and
the highest attribute that can be applied to any aspirant for honor in the
treatment of cardiac diseases is to say it has a "digitalis-like action." It
frequently, however, brings disappointment. This is chiefly because it is
not given in relaxed conditions of the heart and blood-vessels. It no
doubt varies considerably in its composition, depending upon the soil,
atmospheric condition, seasons and general environment, and upon the
freshness of the plant employed.
There are few drugs toward which individual members of the human
family are so generally and differently idiosyncratic. Again, the actions
of watery and alcoholic preparations are by no means identical, owing to
the differences in the solubility of the various glucosides in these
menstrua; an infusion, for instance, holds in solution chiefly the
digitonin, while the tincture contains digitalin and digitalein, neither
contains much digitoxin, but the tincture necessarily carries more than the infusion. Notably the infusion is more directly and promptly diuretic,
and the B.P. tincture more so than that of the U. S. P., but the latter two
afford the best results when the heart alone is to be acted upon. But it is
doubtful if the tincture alone ever acts as a true diuretic, except in the
presence of a heart-lesion, such as is found in connection with some form
of hydrops. The drug often fails completely in securing the desired action
clinically, because the wrong preparation is employed.—(Sajous' Annual).
Digitalis occupies an almost isolated and rather unfortunate position,
because the isolated principles do not constantly represent the medicinal
activity of the whole plant. It is a very important medicine, and unlike
most important remedial plants it refuses to yield up a reliable active
principle. Four active medicinal principles have been isolated, not one of
which fully represents the medicinal virtues of the leaf itself.
Ergot which has a similar action, i. e., vasoconstrictor, has nothing better
to fully represent its medicinal properties than concentrated extracts.
Aconitine, atropine, quinine, morphine, hyoscyamine, strychnine and
colchicine, represent the. medicinal properties of the vegetable substances
from which they are derived. They are reliable and can be given with the
belief and the assurance that certain known results will follow their
internal administration. This cannot be as strongly and as truly said of
any of the products of digitalis. Digitalin has at times disappointed the
writer more than any other active principle, inasmuch as it has failed to
produce such positive, marked and constant results as the infusion. This
is to be regretted exceedingly because of the important position that
digitalis occupies.[Shaller]
The time will unquestionably come when the active medicinal principles
of digitalis shall be uniformly produced, which does not seem to be so at
the present time. Possibly, some one may hit upon the happy and correct
combination of some of the four active principles as they exist in the
plant. It is too late in the history of dosimetry to go into the advantages
of the use of active principles over that of crude drugs. But until each one
is satisfied in his own mind that the isolated substance placed in his
hands can do as much and more than the plant itself, he is justified in
refusing to use it. As long as the physician feels sure that the crude drug is superior to the active principles found in the market, that it produces
better results, he should use the crude drug. He should use whatever
produces the best results in his hands, irrespective of what others may
believe.
The writer confines the use of digitalis almost exclusively to those
conditions in which there is weakening of the muscular structure of the
entire circulatory system, blood-vessels as well as heart, manifested by
relaxation of blood-vessels, venous stasis, oedema, and scanty urine.
Digitalis or digitalin has no place in the treatment of febrile diseases
except in combination with aconitine and strychnine, simply because the
heart beats rapidly. Cactin, strychnine and caffeine are better remedies to
simply sustain the heart-action when it is needed in such cases. Apocynin
has found great favor in the treatment of heart-diseases, in which
digitalis is usually prescribed. It is greatly to be preferred to digitalin. In
its action in reducing oedema and the number of heart-beats, as well as
regulating irregularities, it is equal to digitalis, if not even more reliable.
Besides it is a stomachic and is free from so-called cumulative effects.
Notwithstanding what has been said, if the symptoms are not urgent,
digitalin is given a trial for five days. If no results manifest themselves
within that time, apocynin or infusion of, digitalis is given. If no benefit
accrues, caffeine and strychnine are added to the above remedies. If
oedema is marked and the urine is still scanty, only a few ounces in
twenty-four hours, calomel gr. 3 three times a day for three days is,
given, guarded with codeine if necessary. If these fail, strophanthus or
diuretin is given. If there is no improvement by this time the case is
probably hopeless. Still, various combinations should be tried. The
bowels should be freely moved and sometimes when all efforts seem to
fail, relief will sometimes come.
Medicines that utterly fail in the beginning of treatment sometimes
produce beneficial results when tried at another period. Various
combinations can be made. Keep on trying, and do not give up a remedy
until it has been pushed to produce its physiologic effect. If you stop
short of this, the remedy has not received full justice, and cannot
therefore be condemned.[Shaller]
Physiological Action Digitalis in full doses produces a great rise in
arterial pressure, followed by a marked fall. It acts on the inhibitory
nerves and on the heart muscle; the increased action being due to
vasomotor spasm and to stimulation of the heart itself. A poisonous dose
causes depression and a dicrotic pulse, while the immediate effect of
moderate doses is to stimulate the heart. Its prolonged use weakens the heart muscle by decreasing its normal nutrition.
When given in frequent small doses, where absorption is immediate, it
influences all of the organic functions as a depressant; it produces
irritation of the stomach and bowels, increased action of the kidneys, and
a marked change in the character, regularity and frequency of the pulse
beat. The influence upon the heart is not always uniform in all such
cases, but variable and often unreliable. The influence is marked and
more immediate if a large dose is given and repeated a few times. The
gastric and intestinal irritation is greatly increased, there is purging,
violent vomiting, great prostration with dicrotic or tumultous, irregular,
erratic and uncertain heart action.
In its general irritating influence upon organic function it may cause so
marked an impression upon the renal circulation as to result in spasm of
the vessel walls and suspension of renal action-suppression of urine with
profound albuminuria.
Therapy—Digitalis is the direct heart stimulant. Its influence is sure and
plainly apparent in marked sthenic conditions. In prostration or
profound weakness, in sudden failure from violent injury, from '''surgical
shock or from acute poisoning''', or in the crisis of extreme exhausting or
protracted disease, its influence given in conjunction with general
stimulants is decisive and satisfactory.
The agent sustains the action of the heart, but does not impart tone as
cactus does, by increased nerve force and improved nutrition of the
organ. Its sustaining power can be maintained by proper administration
until other measures supply deficient power, by encouraging reaction, or
by general improved nutrition.
The influence of digitalis in its stimulant effect is nearly diametrically
opposed to that of aconite. In therapeutic action the two agents occupy the
opposite extremes. For this reason digitalis, within the limits of its
stimulant action, is a physiological antidote to aconite.
Digitalis slows a rapid and feeble pulse in asthenic fever. It is a sedative
in fevers under those circumstances in which aconite is contraindicated. In prolonged cases where asthenic conditions prevail, and
where the temperature remains high, with rapid, feeble, easily
compressed pulse or irregular heart action, all the evidences of failure of
vital force, digitalis is the fever remedy. It controls the pulse, reduces the temperature somewhat, and im. proves the heart action. Aconite, veratrum
and the synthetic antipyretics will all increase the condition under such
circumstances and are contraindicated.
In pneumonia, when the disease processes have had full sway, and the
heart is unable to properly fill the pulmonary capillaries, and is
depressed by the influence of the general disorder, and the general
effects of the accumulated carbonic acid within the blood, and is labored
and overtaxed and apparently slowly failing, this agent is directly useful.
It promptly strengthens the heart and the nervous structure of the
pulmonary apparatus at the same time.
In minute doses in children, if it be given with belladonna or other heart
stimulants, it shows a most desirable influence in this class of cases, but
should be stopped as soon as these results are obtained, that no untoward
symptoms may occur.
Digitalis is a remedy for passive congestion where the blood stasis has
occurred from feebleness and failure of the circulatory organs. It
exercises a stimulating influence upon the entire apparatus; through its
power of increasing heart action it imparts renewed force and an
improved capillary tonus in every part. It such cases its influence
resembles that of belladonna, although not so marked nor permanent.
Digitalis is a remedy for passive congestion where the blood stasis has
occurred from feebleness and failure of the circulatory organs. It
exercises a stimulating influence upon the entire apparatus; through its
power of increasing heart action it imparts renewed force and an
improved capillary tonus in every part. It such cases its influence
resembles that of belladonna, although not so marked nor permanent.
In valvular diseases of the heart, with muscular relaxation and
feebleness, it is a good remedy, but not always the best. It sustains the
power for a time in those cases where there is stenosis, and where
compensatory dilatation has previously occurred. In feeble, irregular and
intermittent heart it is frequently prescribed with excellent results.
Digitalis is not found in the urine and does not directly influence the
secretory or the excretory functions of the kidneys. Its apparent influence
upon these organs is. due to the improved blood pressure from its direct influence upon the heart, inducing increased heart action. '''Renal
congestion''' is overcome because the increased heart impulse drives the
blood through the renal capillaries with renewed vigor, and there is thus
a copious flow of the urine from improved renal circulation. Under these
circumstances only, is it a valuable remedy in dropsy. In cardiac dropsy
it acts most promptly if given in infusion in small and frequently
repeated doses. Close watch must be kept for cumulative action. In
dropsy from post-scarlatinal nephritis, a dram or two of the leaves in a
pint of water is thoroughly steeped. Of this from a teaspoonful to a
tablespoonful may be given every two or three hours.
In general dropsy from heart disease there is deficient capillary
circulation, especially when lying down; the pulse is irregular,
intermittent and feeble, the urine is small in quantity, with a large
percentage of albumen. Its power over the heart influences this entire
train of symptoms directly. Patients taking digitalis in full doses for an
immediate effect should remain in the recumbent position. This position
greatly favors its sedative and tonic action, and patients have died upon
being raised to a sitting posture immediately after taking an extreme
dose of this agent. Syncope, especially in children, is common at such a
time. The profound influence of the remedy prevents the occurrence of
the natural change in the action of the heart, from a prone position to the
sitting posture. Digitalis may exercise no apparent influence upon the
system when proper doses are given regularly for some days, until
suddenly violent poisonous effects may appear, with irregular and greatly
depressed heart action, vertigo, extreme wakefulness, vomiting, irritation
of the bowels, with pain and sometimes violent purging.
The cause or manner of its accumulation is variously explained and is
not well understood. Several theories are advanced, none of which are
satisfactory. No other heart remedy has these objections. Cumulative
action often shows itself first by the influence of the agent upon the
kidneys, in suspending or restraining their action. Consequently if
desirable results from the use of this agent do not appear, and there is a
decrease in the quantity of urine passed, the agent should be suspended,
at least for a time.[Ellingwood]
Adverse Reactions Cardiovascular: Sinus bradycardia
Signs and Symptoms of Overdose GI effects (nausea and vomiting)
usually precede cardiovascular effects by several hours. Asystole, AV
block, bradycardia, decreased QT interval and prolonged P-R interval,
fibrillation (atrial), flutter (atrial), heart block (first, second, and third
degree), hypotension, ventricular arrhythmias. Contact dermatitis, delirium, dizziness, confusion, fatigue, headache, hyperkalemia and seeing
yellow halos have also been reported.[PTH]
The cardioactive glycoside content of D. purpurea leaf is 0.15–0.4%, consisting of about 30 different structures. The major components are based on the aglycones digitoxigenin, gitoxigenin, and gitaloxigenin (Figure 5.103), the latter being a formate ester. The glycosides comprise two series of compounds, those with a tetrasaccharide glucose–(digitoxose) 3– unit and those with a trisaccharide (digitoxose)3– unit. The latter group (the secondary glycosides) is produced by partial hydrolysis from the former group (the primary glycosides) during drying by the enzymic action of a β-glucosidase which removes the terminal glucose. Thus, the principal glycosides in the fresh leaves, namely purpureaglycoside A and purpureaglycoside B (Figure 5.103), are partially converted into digitoxin and gitoxin respectively (Figure 5.103), which normally predominate in the dried leaf. These transformations are indicated schematically in Figure 5.104. In the fresh leaf, purpureaglycoside A can constitute about 50% of the glycoside mixture, whilst in the dried leaf the amounts could be negligible if the plant material is old or poorly stored. The gitaloxigenin-based glycosides are relatively unstable, and the formyl group on the aglycone is readily lost by hydrolysis. Other minor glycosides are present, but neither the fresh nor dried leaf contains any significant quantities of the free aglycones.[MNP Dewick]
|
|
"Easily grown in ordinary garden soil, especially if it is rich in organic matter[1]. Prefers a light dry soil in semi-shade[17] but succeeds in full sun if the soil is moist[200]. Grows well in acid soils[17]. Plants are hardy to about -25oc[187]. The foxglove is a very ornamental plant that is easily naturalized in the semi-shade of a woodland[1]. It contains glycosides and forms the basis of an important heart medicine for which it is cultivated commercially[4]. This species is commonly used by herbalists, whereas D. lanata is more commonly grown for supplying the pharmaceutical industry[238]. The plant contains much greater concentrations of the medically active ingredients when it is grown in a sunny position[115]. The flowers are very attractive to bees[4, 24]. Individual plants can produce up to 2 million seeds[4]. Members of this genus are rarely if ever troubled by browsing deer or rabbits[233]. A good companion plant, it stimulates the growth of nearby plants, growing well with pine trees[18, 20, 54]. Special Features:Attractive foliage, Not North American native, Naturalizing, All or parts of this plant are poisonous, Suitable for cut flowers." [PFAF]
Propagation
Seed - surface sow early spring in a cold frame. The seed usually germinates in 2 - 4 weeks at 20oc[175]. When they are large enough to handle, prick the seedlings out into individual pots and plant them out in the summer. If you have sufficient seed it can be sown outdoors in situ in the spring or autumn." [PFAF]
Synonyms