Digitalis. Digitalis purpurea.

Synonym—Foxglove.

CONSTITUENTS—

Digitalin, digitoxin, digitonin, digitalacrin, a stearopten digitalosmin, and digitaloic acid.

PREPARATIONS—

Extractum Digitalis Fluidum, Fluid Extract of Digitalis. Dose, from one to three minims.

Tincture Digitalis, Tincture of Digitalis. Dose, from five to twenty minims.

Infusum Digitalis, Infusion of Digitalis. Dose, from one dram to one. half ounce.

Specific Medicine Digitalis. Dose, from one-sixth to three minims. Prescribed, from five minims to one and one-half drams, in four ounces of water, a teaspoonful every hour or two.

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 contra-indicated. 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 improves 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.

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.

Like cactus, it is not a remedy for violent heart action from over action of the nervous system, or from sthenic conditions.

Cactus is valuable, indeed, in irritable heart from indigestion; in palpitation and irregular action from gastric irritation, while in this case digitalis exercises no beneficial influences whatever. On the contrary, it is apt to increase the gastric irritation. Cactus soothes the irritable stomach and promotes normal functional operations.

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.

The American Materia Medica, Therapeutics and Pharmacognosy, 1919, was written by Finley Ellingwood, M.D.
It was scanned by Michael Moore for the Southwest School of Botanical Medicine.