NUX VOMICA, a poisonous drug, consisting of the seed of Strychnos Nux-Vomica, a tree belonging to the natural order Loganiaceae, indigenous to most parts of India, and found also in Burma, Siam, Cochin China and northern Australia. The tree is of moderate size, with a short, thick, often crooked, stem, and ovate entire leaves, marked with three to five veins radiating from the base of the leaf. The flowers are small, greenish-white and tubular, and are arranged in terminal corymbs. The fruit is of the size of a small orange, and has a thin hard shell, enclosing a bitter, gelatinous white pulp, in which from i to 5 seeds are vertically embedded. The seed is disk-shaped, rather less than 1 in. in diameter, and about 4 in. in thickness, slightly depressed towards the centre, and in some varieties furnished with an acute keel-like ridge at the margin. The external surface of the seed is of a greyish-green colour and satiny appearance, due to a coating of appressed silky hairs. The interior of the seed consists chiefly of horny albumen, which is easily divided along its outer edge into halves by a fissure, in which lies the embryo. The latter is about l a o in. long, and has a pair of heart-shaped membranous cotyledons.
The chief constituents of the seeds are the alkaloids strychnine and brucine, the former averaging about 0.4%, and the latter about half this amount. The seeds also contain an acid, strychnic or igasuric acid; a glucoside, loganin; sugar and fat. The dose of the seeds is i to 4 grains. The British Pharmacopoeia contains three preparations of nux vomica. The liquid extract is standardized to contain 1.5% of strychnine; the extract is standardized to contain 5%; and the tincture, which is the most widely used, is standardized to contain 0.25%.
The pharmacology of nux vomica is practically that of strychnine. The tincture is chiefly used in cases of atonic dyspepsia, and is superior to all other bitter tonics, in that it is antiseptic and has a more powerful action upon the movements of the gastric wall. The extract is of great value in the treatment of simple constipation.
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