This section is from the book "Materia Medica And Therapeutics: An Introduction to the National Treatment of Disease", by John Mitchell Bruce. Also available from Amazon: The pharmacology and therapeutics of the materia medica.
The seeds of Strychnos Nux vomica, Imported from the East Indies.
Characters.-Nearly circular and flat, about an inch in diameter, umbilicated and slightly convex on one side, externally of an ash-grey colour, thickly covered with short satiny hairs, internally translucent, tough and horny; taste intensely bitter; inodorous.
Composition.-Nux vomica seeds contain two alkaloids: •2 to •5 per cent. of strychnia, and •12 to 1•0 per cent. of brucia. united with a crystalline acid, strychnic or igasuric acid, with the ordinary constituents of seeds.
Brucia, C23H16N2O4 , occurs in colourless prisms, pearly flakes, or masses. It is soluble in alcohol; much more soluble in water, less bitter, 38 times weaker, and 3 times slower physiologically than strychnia.
Preparations of Nux Vomica.
Extractum Nucis Vomicae. Spirituous. 16 in 1. Dose, \ to 1 gr.
Tinctura Nucis Vomicae. 1 in 10. Dose, 5 to 30 min.
From Nux Vomica is made:
Strychnia. Source. - Made from Nux vomica by
(2) adding Ammonia to the solution, to precipitate the alkaloids; (3) dissolving out the Brucia by boiling Spirit, and crystallising out the Strychnia by evaporation and cooling; (4) purifying by repetition of process (3).
Characters.-Strychnia, C21H12N202, occurs in very small colourless prisms, inodorous, intensely bitter (but not to be tasted by the student except in very weak solutions). Solubility, 1 in 6,500 of cold, in 2,500 of boiling water.
Impurity.-Brucia, giving red with HN03.
Dose.- 1/30 gr., gradually increased to 1/8 gr., always in solution.
Preparation of Strychnia.
Liquor Strychnia,.-4 gr. to 1 fl.oz. of Spirit, Water, and Diluted Hydrochloric Acid. Dose, 4 to 10 min.
Externally.-Strychnia is a powerful antiseptic, but is too poisonous to be applied to wounds.
Internally.-Nux vomica and strychnia possess all the properties of bitters as described under Calumba (page 181), to which the student will refer. Their use is not different from that of other bitters, excepting that whilst they are unpleasant from the intensity and persistency of their taste, and the absence of all covering flavour, they are very convenient on account of their small bulk. The Tincture of Nux Vomica is to be prescribed with alkalies, the Liquor Strychniae with acids.
Strychnia enters the blood from mucous surfaces, or when given hypodermically. Here it affects both the red corpuscles and the plasma, reducing the absorptive power of the former for oxygen, and the discharge of carbonic acid from the latter. These effects are not, however, the cause of the specific action of the drug immediately to be described.
Strychnia quickly finds its way into the viscera, especially the nervous system, and is peculiar in remaining so long within them, that it is not wholly excreted for several days. Entering rapidly, and disappearing slowly, the alkaloid accumulates in the body if the dose, however small, be very frequently repeated, and is said to have a "cumulative action."
In medicinal doses, strychnia produces a tonic influence, as described under Calumba and Quinia, with a sense of increased strength and spirits. Therewith its specific action is soon developed, namely, increased sensibility of touch, sight, and hearing, with some disorder of the senses, such as of colour, vision, and smell. Repeated or larger doses next lead to sudden twitchings of the muscles of the limbs, a constricted feeling in the chest, and some dysphagia, with a sense of anxiety. Poisonous doses produce violent convulsions, and rapid death by exhaustion and asphyxia, from spasmodic arrest of the respiratory muscles. The phenomena resemble tetanus, but differ from it in the complete relaxation of the muscles between the convulsive seizures, in the great rapidity of their course, and in the comparative absence of trismus (lock-jaw).
Careful analysis resolves the phenomena of strychnia poisoning as follows, and enables us to understand its action in medicinal doses. The convolutions are unaffected. The motor centres of the cord are powerfully irritated by toxic doses, and this in such a way that their reflex excitability is enormously increased. The very slightest stimulation of the skin, such as a breath of air, a loud sound, or a bright light, is sufficient to originate reflex muscular spasms. The muscles of respiration are manifestly involved in this effect, and the vigour of their action greatly increased; and this is carried so far that they remain contracted in inspiration, and give rise to asphyxia.
The medulla is stimulated by strychnia in all its important centres. The respiratory centre is increased in activity, and transmits powerful impulses downwards to the already excited cord, thus causing increased frequency and depth of the movements of the chest. The cardiac centre and the cardiac ganglia and nerves appear to be stimulated by strychnia, but the violent contractions of the voluntary muscles completely modify the direct effect of the alkaloid, which is said actually to cause slowing of the heart (in animals paralysed by curare). Death does not occur through the heart, which beats after respiratory death, and remains contracted. The vaso-motor centre is also increased in vigour, an effect which is heightened by the general muscular spasm, and finally by the asphyxial state of the blood; thus the arterial pressure rises enormously for a time.
The motor nerves and muscles are comparatively unaffected by strychnia, but its local application appears to stimulate them. Probably the same may be said of the sensory nerves, vision being improved by injections of strychnia in the temple. The body temperature naturally rises during the convulsions.
Strychnia is indicated in paralysis, especially paralysis from disease or disorder of the cord, but is not of much real service in this class of cases. Its function in cerebral disease is mainly to sustain the activity of the spinal centres, nerves, and muscles until the higher centres are restored; but electricity has almost entirely displaced it for this purpose It appears, however, to be useful in the so-called " reflex," or "functional," paralysis of neurotic subjects, diphtheria, or anaemia; and in peripheral paralysis, of the fore-arm, eyes, larynx, sphincters, etc., often toxic in origin, e.g. due to lead, tobacco, or alcohol. For these local cases, strychnia is best given in the form of hypodermic or intra-muscular injection (1/48 gr. of sulphate of strychnia in 10 min. of distilled water). In sensory paralysis strychnia is useless, but it appears to relieve some forms of blindness (amaurosis) when applied locally, i.e. hypodermically in the temple. In chronic nervous disorders, such as chorea, epilepsy, neuralgia, and asthma, it is of benefit as a bitter stomachic and tonic, an effect more generally available than the specific action of the drug.
Strychnia, as a respiratory stimulant, may be used in bronchitis, emphysema, and phthisis, to increase the vigour both of the respiratory centre and the respiratory movements. It is advantageously combined with expectorants, its tonic action being further useful. From its stimulant and tonic action on the heart and vessels, it is given with benefit in cardiac dilatation with low pressure.
Strychnia is a physiological antagonist of chloral, morphia, and physostigma, and may be given in moderate doses in poisoning by these substances, whilst all the ordinary methods of recovery are persevered in.
Strychnia is excreted in the urine, sweat, and saliva, as we have seen, very slowly. The practical importance of this fact has already been insisted on.