Strophanthus

STROPHANTHUS, Strophanthus hispus DC. and Strophanthus Kombe-Oliver, a shrubby plant of the dogbane family (Apocynaceae). There are more than 28 separate species of Strophanthus. From them are obtained seeds used for medical purposes. It grows mainly in Africa and partly in southern Asia (India and nearby islands). Various species of Strophanthus are usually climbing, sometimes erect shrubs, subshrubs, and small trees. The leaves are opposite, sometimes leathery. The flowers are collected in panicles, terminal or lateral. The fruits reach 30 cm in length and contain up to 200 seeds. The seeds are up to 2 cm in length, provided with a pappus connected to the seed by a long thread. The seeds of Strophanthus contain the nitrogen-free glycoside strophanthin. Natives prepared poison from Strophanthus seeds for poisoning arrows (oupou). By Prof. Pelikan together with Vulpian, this poison was investigated and described in 1865 as a cardiac poison. The structural formula of strophanthin is unknown. The strophanthins obtained from different species of Strophanthus differ somewhat from each other both in chemical composition and degree of toxicity. They are distinguished by adding the initial letter of the species name to the word strophanthin. Practically the most interesting have proven to be the following three: Strophanthinum-k (from S. Kombe), having the formula C₂₅H₃₈O₇, Strophanthinum-h (from S. hispidus), C₃₁H₄₇O₁₂ and Strophanthinum-g (from S. gratus), or Ouabain-C₃₀H₄₆O₁₂. The k- and g-strophanthins have the greatest significance. In medicine, both the extracted poisons (glycosides) in pure form and alcoholic tinctures from the seeds (T-ra Strophanthi) are used. Since the content of the poison in the seeds varies and depends on a number of conditions, according to the requirements of the VI edition, Strophanthus preparations must be pre-standardized: Strophanthus seeds must contain in 1.0 not less than 2,000 frog units, and T-ra Strophanthi in 1.0-200-250 frog units. Pharmacologically, Strophanthus belongs to the digitalis group. With local action, strophanthin causes a feeling of pain, which then passes into anesthesia (anaestheticum dolorosum). Strophanthin that enters the blood acts selectively on the cardiovascular system. The nature and mechanism of its action are similar to those of digitalis (see Digitalis). The differences from digitalis consist mainly in the following: 1) absorption of strophanthin occurs significantly faster (when taken orally its effect is already detected after about 15 minutes); 2) excretion of strophanthin from the body also occurs much faster than that of digitalis; for this about 3 days are required; therefore 3) the phenomena of cumulation with Strophanthus are expressed much weaker than with digitalis; 4) the vasoconstrictive effect on the intestinal vessels with Strophanthus is significantly weaker than with digitalis; 5) blood flow through the coronary vessels with Strophanthus is significantly increased and 6) the minimum lethal dose with strophanthin is significantly less than with digitalis. The indications for prescribing strophanthin are generally the same as for digitalis, but in cases of acute cardiac weakness, due to better absorption, strophanthin is preferred to be prescribed; in the same cases where a long-term effect on the heart muscle is needed, digitalis is preferred. In cases of acute heart weakness, strophanthin can be administered intravenously, however, extreme caution must be observed, since strophanthin is significantly more toxic when administered intravenously than when administered orally (when administered orally, strophanthin cumulates little). Repeated intravenous injections should not be performed earlier than after 7 days. Contraindications to the prescription of strophanthin, according to data from the Dutch Institute for Pharmacotherapeutic Research, are: chronic nephritis with hypertension, acute myocarditis, angina pectoris, Basedow's disease. Preparations: 1) T-ra Strophanthi orally 2-10 drops several times a day. Highest dose (FUP)-0.5(1.5). 2) Strophanthinum cryst., g-Strophanthinum, or Ouabain. Crystals of the pure glycoside from Str. gratus are soluble in 100 parts of cold water and 30 parts of absolute alcohol; easily soluble in hot water, difficultly in chloroform and ether. When heated with diluted acids, it undergoes hydrolysis. Orally 0.0005-0.001 several times a day. When administered intravenously, the dose should not exceed 0.0005. Re-administration cannot be done earlier than 48 hours. 3) Strophanthinum Boehringer=k-S. Well soluble in water, alcohol, insoluble in chloroform, ether; similar to the previous one. 4) Parastrophanthinum - tablets containing 0.0005-0.001 g-S., or in ampoules of 0.00025-0.0005.