The dried ripe seeds of Strophanthus Kombé, Oliver, or of Strophanthus hispidus, DeCandolle, deprived of their long awns (Nat. Ord. Apocynaceae). West and east coast of tropical Africa. Dose, 1 to 2 grains.
Principal Constituents.—Strophanthin (C31H48O12—8 to 10 per cent), a bitter glucoside yielding glucose and strophanthidin (see below), kombic acid, inert alkaloid ineine and tanginin.
Preparation.—Tinctura Strophanthi, Tincture of Strophanthus. Dose, 1 to 10 drops.
Derivative.—Strophanthinum, Strophanthin. Commercial strophanthin is a glucoside or mixture of glucosides occurring as a permanent white or yellowish powder, readily soluble in water and diluted alcohol; less soluble in absolute alcohol; and almost insoluble in ether and chloroform. It should not be tasted except in very dilute solution. Average Dose, 1/60 grain (by mouth); 1/80 grain (intravenously).
Specific Indications.—Weak heart, due to muscular debility; muscular insufficiency; rapid pulse, with low blood pressure; cardiac pain, with dyspnea.
Action.—Externally applied, strophanthus preparations appear to exert no special effects unless mixed with hydrous wool fat, when the action of the drug is said to be apparent. The seeds, however, applied to the cornea produce prolonged anesthesia (Steinbach). Three or four drops of a solution of strophanthin (1 to 1000) applied to the cornea also produce total anesthesia, including insensibility to heat and cold (difference from cocaine), these sensations being the last to yield and the first to revive after its application. De Schweinitz and Hare found that ocular anesthesia occurs only in dogs, not in man. A disagreeable irritation of the conjunctiva has been produced by this use of strophanthin; it has no effect on intraocular pressure or upon vision -accommodation. Strophanthus is a muscle poison. When taken internally it acts primarily upon the voluntary muscles, increasing their contractility, and if the dose be poisonous it causes tetanic paralysis, the muscles being unable to regain their former normal flexibility. Under its toxic influence the muscles first become enfeebled, then somewhat rigid, fibrillary twitchings, which are spontaneous, non-rhythmical and increasing contractions, somewhat similar to those of chorea, are observed, and finally the muscles become pallid, non-contractile and hard. It is these effects that render strophanthus an efficient arrow-poison, the muscular paralysis produced rendering the animal an easy prey to its pursuer. When the muscles are in extreme paralysis, lactic acid has been observed to replace the normal alkaline condition. Strophanthus muscular paralysis consists chiefly in diminishing the ability of the muscles to relax, and then in destroying this capability, producing a condition difficult to distinguish from rigor mortis.
Strophanthus does not appear to affect either the spinal cord or to act upon its nerve trunks. Its specific action upon the heart is due to direct contact (through the blood) with the muscular fibres of that organ, and not to any effect upon the cardiac nerves. A large dose so increases contractility that a more perfect, energetic, and prolonged systole is the result, and the capability of the muscle to relax is lost, or so diminished that diastole can not take place; after death the ventricle is so completely contracted as to almost efface the cavity, the heart passing from life directly into rigor mortis. According to some it may cease either in systole or diastole. The caliber of the blood vessels is but little influenced by strophanthus, it having no effect upon the vaso-motor control. It is strongly diuretic in so far as lack of secretion depends upon low blood pressure, i. e., it increases diuresis in so far as increased blood pressure produces an increased urinary product. It is also thought by some to act especially upon the renal secreting structures. When one is in good physiological condition it is said to have little or no diuretic action; but in diseased conditions, with low blood pressure, it is asserted to excel digitalis in diuretic power.
If strophanthus be given in large doses it produces gastro-intestinal irritation with vomiting and diarrhoea. Small doses, however, act as a bitter tonic, improve the appetite, augment gastric action, and promote digestion. In proper doses it strengthens the heart-muscle, slows cardiac action, increases the interval between beats, reduces the pulse-rate, and powerfully increases arterial tension (but less so than digitalis), not by any effect (to any extent at least) upon the vessels, but by strengthening the heart-muscle, giving increased power. Whether or not the drug is cumulative is still an unsettled question, though it probably is not unless given too freely in overlapping doses. The action of a good strophanthus upon the heart is probably greater than that of any other drug, and its active principle, when pure, is of far greater potency than the digitalis derivatives.
Therapy.—Strophanthus is a remedy for weak heart from debility of the cardiac muscle, with lack of proper contractile power, as shown by a rapid, weak pulse, and very low blood pressure. The disordered action of the heart is due to lack of tonicity and not from weak walls due to deposition of fat, in which case the drug must be used with extreme circumspection, though in small doses it has been recommended by some as a remedy for cardiac fatty degeneration, as it has also in atheroma of the arteries in the aged. It is also a remedy for praecordial pain and for cardiac dyspnea. It has been strongly endorsed in heart affections with disorders of compensation. Strophanthus is useful in valvular heart disease only so far as there is muscular insufficiency, where the compensatory increase of muscular action is not sufficient to offset the valvular insufficiency. "It has been reported useful in cases of mitral regurgitation with dilatation; mitral stenosis with regurgitation; regurgitation with edema, anasarca, dyspnea, etc.; mitral insufficiency with palpitation, praecordial pain, cyanosis, dyspnea, etc." (Annual of Eclectic Medicine and Surgery, Vol. I, page 25.) Schiller (ibid., page 40) says: "When the balance in the circulation has become impaired, as a result of insufficiency of the valves of the heart from organic disease with a general dropsical condition, strophanthus, although affording temporary relief in some cases, has failed in every case in my hands to reestablish the compensation. The result was the same whether the mitral, the tricuspid, or the semilunar valves were most involved." These are the cases of heart disease in which digitalis is the remedy. However, evidence is strong to show that when the muscular insufficiency can be corrected in these cases then the remedy will do good service. Schiller looks upon the drug as a remedy for what is ordinarily termed functional heart disease, when not sympathetic. The heart-action is rapid or abnormally slow, or the rhythm is bad, a condition common in school children at puberty when forced to overstudy. Strophanthus is well endorsed as a remedy for the irritable heart of tobacco smokers, masturbators, and those addicted to the use of alcoholics and narcotics.
Acute endocarditis and the reflex palpitation of neurasthenic, hysterical, and chlorotic subjects have been signally benefited by strophanthus, while it appears to give better cardiac power during or after typhoid and other adynamic fevers, when heart failure threatens. It should be remembered as a remedy for threatened cardiac failure in any disease. Full doses should be given for the relief of angina pectoris, and the remedy should be continued for a period after the attack. It is less efficient, because slower in action, than amyl nitrite or nitroglycerin, but may be given for more permanent effects after the evanescent action of these agents has passed off. In pulmonary congestion and in acute bronchitis or acute pneumonia it may be employed when there is deficient heart power.
Strophanthus has been praised for prompt results in cardiac asthma and bronchial asthma, with edema; in whooping cough it has many advocates. Goitre is asserted to have been cured with it, and large doses (8 to 25 drops of the tincture several times a day) have been said to cure a large proportion of cases of exophthalmic goitre, with irregular cardiac action. Schiller reported great relief to the heart symptoms in two cases of exophthalmic goitre, with disappearance of the bronchocele in one case (Annual of Eclectic Medical and Surgery, Vol. I, page 40). Strophanthus has also been lauded as a remedy for chronic nephritis, with albuminuria, in anasarca, and in ascites from hepatic cirrhosis. It is of little value in edema and other forms of dropsy or kidney affections unless dependent upon cardiac disorders.
Strophanthus does not take the place of digitalis, each having its own field of action. It may, however, follow the use of other heart tonics, and particularly those evanescent in action, as amyl nitrite and nitroglycerin. As it does not affect the caliber of the vessels, it may be used in preference to digitalis when it is not desirable to add extra work to the heart. It is well borne by the aged and by children. Wilcox (Materia Medica) sums up the advantages of strophanthus over digitalis as follows: "Greater rapidity, modifying pulse-rate within an hour or two; less marked vaso-constrictor effects; greater diuretic powers; no disturbance of digestion from properly made preparations; absence of so-called cumulation; greater value in children; great safety in the aged." He further summarizes its uses as follows: "It should, therefore, be the remedy of choice for all patients in whom we wish to establish compensation; for arterial degeneration in which a remedy which causes more energetic cardiac contraction is required; for cardiac disease when a diuretic is necessary; for weak or irritable hearts; and for the treatment of cardiac disease in childhood or old age." These we would qualify by adding when the heart-muscle is at fault.
Strophanthus should be avoided or very cautiously used in advanced muscular degeneration, in pronounced mechanical defects of the heart, and in fully and over-compensated hearts. Strophanthus is also contraindicated in aneurism, advanced myocardial degeneration, and in well developed atheroma and arteriosclerosis. Unfortunately there is a great variation in strength in various batches of tincture of strophanthus owing to lack of uniformity in the crude drug employed. The dose of tincture of strophanthus is from one to ten drops; of strophanthin, 1/500 to 1/60 grain, all of which should be cautiously administered.
The Eclectic Materia Medica, Pharmacology and Therapeutics, 1922, was written by Harvey Wickes Felter, M.D.