Source and Composition. Strophantus is the seed, deprived of its long awn, of Strophantus hispidus (nat. ord. Apocynaceae), an African climbing-plant, from which the natives extract a poisonous preparation known as the Kombè arrow-poison. It contains a crystalline glucoside, Strophantin, the active principle, which is plentiful in the seed (8 to 10 per cent.) and is an agent of great energy, the frog being killed by a solution of 1 in 10,000,000. (Denian.)
Preparations. Professor Frazer recommends the tincture.
- Tinctura Strophanti, (1 in 20),—Dose, ♏v-x, or ♏½-ij frequently repeated. A stronger tincture, (1 in 8), is on the market.
- *Strophanthinum, Strophantin,—Dose, gr. 1/120-1/60 hypodermically; gr. 1/50 has been used, the influence of the one injection upon the circulation lasting at least 8 days. Soluble in water and in alcohol.
Physiological Action. Strophantus acts primarily upon muscular tissue, by direct contact through the blood, and with great energy. It increases the contractile power of all striped muscle, and in poisonous quantity it fixes the muscular contraction into a condition of tetanic permanence, the muscle being unable to resume its normal condition of partial flexibility.
Small doses stimulate the cardiac contractions, increasing the force of the ventricular systole, and lowering the rate of the heart-beats. At the same time the general blood-pressure is raised, and diuresis produced, both being due to the direct stimulation of the circulation from behind. Large doses paralyze the heart in systole, and leave the cardiac muscle in a state of contraction resembling cadaveric rigidity. It does not act through the nervous system, but paralyzes muscular tissue, striated and non-striated, by direct contact ;—and when contractility has been once destroyed thereby, no stimulus will re-excite it. It does not affect the vascular system directly.
Compared with Digitalis, then, we have in Strophanthus a much more powerful cardiac stimulant, differing from Digitalis in not producing vasomotor constriction of the arterioles. It reduces the pulse, lowers body-temperature somewhat, is not cumulative in action, and does not cause any gastrointestinal disturbance. It is diuretic, by direct stimulation of the renal circulation; and has power over rigors, by its rapid cardiac action, stopping them and preventing their recurrence.
Therapeutics. Strophanthus is a valuable cardiac stimulant, from the rapidity and permanence of its action, as well as its non-interference with the calibre of the peripheral vessels. It relieves cardiac dyspnoea promptly, in less than an hour it modifies the pulse-rate, and the influence of a single dose upon the circulation persists for a long time. It may replace Digitalis in the treatment of chronic Bright's disease and valvular lesions of the heart, where it is important that the work of the heart should not be increased by any additional resistance in the arterial system. It has been recently admitted to the pharmacopoeia, and is reported as highly useful in many cardiac and renal affections; but the claims made for it have not been corroborated by experience, so that the drug is gradually falling into disuse.
A Compend of Materia Medica, Therapeutics, and Prescription Writing, 1902, by Sam'l O. L. Potter, M.D., M.R.C.P.L.