This section is from the book "Materia Medica Pharmacy, Pharmacology And Therapeutics", by W. Hale White. Also available from Amazon: Materia Medica Pharmacy, Pharmacology And Therapeutics..
Strophanthus. - The seed of Strophanthus hispidus De Can-dolle (nat. ord. Apocynaceae), deprived of its long awn.
About 15 mm. long and 4 or 5 mm. broad, oblong-lanceolate, flattened and obtusely edged, grayish-green, covered with appressed, silky hairs, one side with a ridge extending into the attenuated, pointed end; kernel white and oily, consisting of a straight embryo, having two thin cotyledons, and surrounded by a thin layer of perisperm; nearly inodorous; taste very bitter.
The chief constituents are - (1) Strophanthin, C31H48O12. It exists in all parts of the plant, but mostly in the seeds (8 to 10 per cent.). This is in all probability the same as, or closely allied to, the active principle Ouabain see p. 416 which has been isolated from another species of Strophanthus. It is a transparent, white, imperfectly crystalline, bitter glucoside, (being split up by acids into glucose and Strophanthidin). Very soluble in water; insoluble in Chloroform and Ether. Strophanthin, according to recent investigation, can be isolated from Strophanthus Kombe, and many other species of Strophanthus. (2) Kombic Acid, which is not identical in all varieties of Strophanthus. (3) Ineine, an Alkaloid. (4) Tanghinin, C27H40O8, in rhombic prisms.
Strophanthus, 50. By digestion and percolation with Alcohol and Water to 1000.
Dose, 2 to 10 m.; .12 to .60 c.c.
Tincture of Strophanthus Kombe, from which the oil has been extracted and made from assayed material, is far more reliable. Of this the maximum dose is 5 m.; .30 c.c
Gastro-intestinal tract. - Like digitalis, strophanthus is liable to cause vomiting and diarrhoea, especially if the dose be large. Generally these disturbances result from preparations from which the volatile oil contained in the seeds has not been extracted. In small doses its bitter action may come into play, and then it will aid digestion like any other bitter stomachic.
Heart. - Strophanthus acts on the heart exactly like digitalis, for it strengthens the force without altering the duration of the systole, slows the rate of the beat, and consequently prolongs the diastole, and makes an irregular heart regular. In fatal cases of poisoning by strophanthus, the heart may be arrested either in diastole or systole. The details of its cardiac action are the same as those of digitalis.
Vessels. - It does not constrict the peripheral vessels, or at any rate very slightly; therefore, the slow rise of blood-pressure is almost entirely due to the action of the drug on the heart. This is the most important difference between it and digitalis, which contracts the vessels powerfully and consequently gives a greater rise of blood-pressure, and is the reason for the greater safety of the former.
Kidneys. - It is diuretic, more powerfully than digitalis. Probably the diuresis is entirely due to the increased cardiac action. No special alteration in the size of the renal vessels takes place under strophanthus.
Nervous system. - This is not affected. In toxic doses it is a direct poison to the voluntary muscles. Strophanthin is a powerful local anaesthetic when dropped on the conjunctivas of dogs.
Respiration. - No particular effect is produced. The African Kombe arrow poison is made from strophanthus.
Strophanthus is used in the same varieties of cardiac disease as digitalis; that is to say, when it is desirable to slow the heart, to increase its force, to make it regular, and to prolong the diastole. It is clear, therefore, that it will be chiefly valuable in cases of mitral disease. A priori, it might be thought that as strophanthus does not contract the peripheral vessels and so increase the cardiac resistance, consequently it would be the more useful drug, and experience has confirmed this for certain cases; it will generally happen that strophanthus will not produce vomiting when digitalis does. The advantages which strophanthus possesses over digitalis may be summed up as (1) greater rapidity, modifying pulse rate within an hour; (2) absence of vaso-constrictor effects; (3) greater diuretic powers; (4) no disturbance of digestion from properly made preparations; (5) absence of so-called cumulation; (6) greater value in children; and (7) greater safety in the aged.
It should be the remedy of choice in all cases, (1) in which we wish to establish compensation; (2) of arterial degeneration in which a remedy which causes more energetic cardiac contraction is required; (3) of cardiac disease when a diuretic is necessary; (4) of weak or irritable hearts; (5) of cardiac disease in childhood or old age. Strophanthus is preferable to digitalis when it is wished to give one of these drugs in Bright's disease.