This section is from the book "Botanic Drugs Their Materia Medica, Pharmacology and Therapeutics", by Thomas S. Blair. Also available from Amazon: Botanic Drugs, Their Materia Medica, Pharmacology and Therapeutics.
Strophanthus species universally official, S. hispidus in the U. S. and six other countries, S. Kombe in the U. S. and ten other countries. The latter is the better species, but supplies of it are often hard to secure.
Strophanthin is a mixture of glucosides obtained from strophanthus. That official in the U. S. P. is given in an average dose of 1-200 grain, the average daily by mouth 1-60 grain and intravenously 1-80 grain. Kombe strophanthin and Hispidus strophanthin are amorphous bodies freely soluble in water. The crystalline strophanthin differs from these; it is obtained from Strophanthus gratus or from Acocanthera ouabaio. This crystalline product is known as Ouabain, Crystallized, or G. Strophanthin. The pharmacologic action, qualitatively considered, is the same with all of these products; but crystallized ouabain is more active than the official strophanthin when injected subcutaneously or intravenously. Strophanthin has no cumulative action.
MacKenzie noted that fever interferes with the action of digitalis. Gum, after detailed study, determined that this is not true of strophanthin when administered intravenously; that elevation of temperature seemed to make the drug action more rapid, and that the reason for MacKenzie's observation is that the heart, in febrile diseases, is in a refractory state from the presence of toxins.
Clark (The Jour. of Phar. and Ex. Ther., Jan., 1914) reported that the systolic action of strophanthin is opposed by the presence of acid, by the absence of calcium, and by the hypodynamic condition.
Crystallized strophanthin - ouabain - is absorbed so slowly and irregularly that the oral administration of the drug is considered unsafe.
Bailey (The Jour. of Phar. and Ex. Ther., Oct., 1909) presented a paper that has guided us ever since in the use of ouabain. For intravenous or intramuscular administration we use 1-130 grain (0.0005 Gm.) dissolved in 4,000 to 8,000 parts of 0.85 per cent. of sodium chloride, and this dose must be given not more than once in twenty-four hours. Ampules of ouabain are prepared of this strength and ready for use.
Bailey highly recommends the intravenous dosage as a quick and certain heart stimulant, using the solution twice as dilute in intravenous administration as in the intramuscular. Broken compensation and all forms of chronic valvular disease respond well to the treatment; but he emphasizes the point that this is strictly an emergency treatment and is not suited for continuous stimulation, digitalis being preferable and much safer.
Strophanthin causes very little vasoconstriction and does not raise blood-pressure in medicinal dosage; but it must not be forgotten that it is a muscle poison and very toxic.
Strophanthus and strophanthin are much more prompt in action than is digitalis. In severe heart cases it is well to begin treatment with strophanthus and follow up with digitalis. In shock and collapse strophanthus is almost invaluable.
Don't confuse the different products described. The U. S. P. strophanthin may be given by mouth; ouabain should not be so administered. The best way to use the U. S. P. strophanthin is to dissolve 1-5 grain in 3 fluidounces of diluted alcohol; then give one teaspoonful of this solution, diluted with water as used, three times a day. This alcoholic solution will be absorbed. Don't use the U. S. P. strophanthin intravenously or intramuscularly; use ouabain.
The tincture of strophanthus of the U. S. P. IX is an admirable preparation that should become very popular with physicians. The preliminary de-fatting of the seed with purified petroleum benzin removes the nauseating oil, and the new tincture is sufficiently strong in alcohol to be stable. Average dose, 8 minims.