This section is from the "A Practical Treatise On Materia Medica And Therapeutics" book, by Roberts Bartholow. Also available from Amazon: A Practical Treatise On Materia Medica And Therapeutics
In small medicinal doses ergot does not produce sensible physiological effects. In large doses it causes symptoms referable to the gastro-intestinal canal, and to the cerebro-spinal axis. It is bitter to the taste, and excites more or less heat and dryness of the throat, followed by thirst, stomach-pain, vomiting, intestinal pain, and occasionally purging. These gastro-intestinal symptoms are unquestionably due to the local irritant action of the drug; for, after death, in a few fatal cases which have resulted from its administration, there have been found patches of inflammatory redness in the stomach and intestines.
The active constituents of ergot diffuse into the blood. What changes, if any, are caused in the composition of the blood, are at present quite unknown. Very characteristic effects are, however, produced in the circulatory system: the action of the heart becomes slower, and an enormous rise takes place in the blood-pressure. This influence on the circulatory system modern research has shown to be due to the action of ergot on the vaso-motor nervous system; it increases the action of this system, and causes a contraction of the arterioles.
The dilatation of the pupil which follows is another evidence of this action. Pain in the head (usually frontal), dimness of vision, giddiness, and stupor, are also produced by it. The action of ergot on unstriped muscular fiber is further shown in the contractions of the parturient womb, the arrest of haemorrhage, and the difficulty of micturition, which follows its medicinal administration. The power of ergot to contract the arterioles has been repeatedly demonstrated in the web of the frog's foot.
The phenomena above described, due to the administration of large medicinal or toxic doses, are known as acute ergotism. The peculiar morbid effects of ergot, when used for a long period of time as food (diseased grain), are known as chronic ergotism, which exists in two forms, the convulsive and gangrenous. Generally the convulsive form begins by vertigo, disorders of vision, tinnitus aurium, numbness of the fingers and toes, and afterward of the integuments of the body. These symptoms are followed by tetanoid contractions of the fingers, of the forearms on the arms, and of the arms against the chest; of the toes on the palmar surface of the foot, of the leg on the thigh. The thoracic, abdominal, and diaphragm muscles are also tetanically contracted, and respiration becomes painful and difficult, and attacks occur similar to asthma. The intestinal muscles become affected by cramp, doubtless tetanoid in character, colics ensue, and diarrhoea; the uterus in pregnant females takes on action, and abortion may result. The pulse is small, action of heart slow, and the surface cold. The appetite is generally ravenous.
The tetanic spasms, at first separated by distinct intervals, become continuous, and opisthotonos or emprosthotonos is produced. Anaesthesia (complete) of the surface succeeds to the tetanoid attacks, and gangrene of limited spots may occur. The organs of sense lose their sensibility and taste, hearing and smell are abolished. The pupils are dilated, sometimes unequal, and various disturbances of vision ensue. Epileptiform convulsions may occur in addition to the tetanoid spasms, delirium sets in, and complete insensibility at last supervenes.
As has been shown by Laségue and Tardieu, the gangrenous and convulsive forms of chronic ergotism are not separated by any well-marked pathological differences. The gangrenous form begins by tingling, numbness, formication, an insupportable sense of fatigue in the members, an earthy hue of the skin, coldness of the surface; nausea, vomiting, and diarrhoea, with intestinal cramps, then occur; muscular contractions take place; an eruption of vesicles filled with a dark ichorous fluid appears on one or more extremities, and gangrene, dry or moist, quickly destroys the toes, the legs, the nose, or other parts.
The phenomena of chronic ergotism are evidently due to two causes —to the dyscrasia which exists in the subjects of this malady, owing to insufficient food and bad hygienic surroundings, and to the action of the ergot of the diseased grain, in diminishing the blood-supply to the cerebro-spinal axis, to the vegetative organs, and to the skin and muscular system.
To this general sketch of the actions of ergot, it may be well to add some particulars of its most important physiological properties, and some observations on the actions of the recently discovered active principles. The most conspicuous effect of ergot, and that on which depends its therapeutical applications, is the influence which it exerts over the vascular apparatus. It is an undoubted fact, in respect to which all the investigators agree, that ergot diminishes the number and alters the character of the cardiac pulsations. The frog's heart may be arrested in the diastole by the intravenous injection of a full dose. By Rossbach and Wernich it was observed that a vermicular or peristaltic motion was given to the heart of frogs. The arrest of the heart's action is attributed by Eberty to stimulation of the vagus and a consequent increase of the inhibition. By Rossbach it is referred to an action on the cardiac muscle. It is in a high degree probable, however, that the slowing and depression of the cardiac functions is due to the action of ergot on the cardiac ganglia. To this may be opposed the observation of Willebrand, that the normal or hyperto-phied heart so contracts under the action of ergot that the difference in size is appreciable by percussion! There is no dispute in regard to the contraction of the arteries induced by ergot. It has been observed and measured by Wernich, Briesemann, and Holmes. The notion that ergot causes contraction of the arteries by stimulating the vaso-motor system and its muscular apparatus has long been entertained. An enormous rise in the blood-pressure has been stated to occur by Eberty, Kohler, and H. C. Wood, and their opinion was based on kymographic observations. Holmes, Hermann, and Wernich, on the other hand, maintain that the blood-pressure is actually reduced. Wernich shows that the veins are dilated, and that a great accumulation of blood takes place in them, while, at the same time, the arteries contract, not receiving from the slowly acting heart sufficient blood. The contraction of the arteries is not, therefore, an active contraction, as has been supposed, but a collapse, the result of deficient supply of blood, which has accumulated in the dilated veins. By the theory of vaso-motor stimulation, it was easy to explain the action of ergot on the muscular fiber of the uterus and intestinal canal. If, however, the blood-pressure falls after the administration of considerable doses, as Handelin, Brown-Séquard, and others affirm, and the arterial contraction is not active, how explain the uterine and intestinal action of ergot? This result is due to arterial anaemia (Wernich, Schlesinger, Mayer, etc.). It is now clearly established that active movements occur in the muscular fiber of the intestinal canal and uterus by inducing an arterial anaemia. According to this view, then, the active peristalsis and the uterine contractions which follow the exhibition of ergot are the result, not of a direct stimulation of the sympathetic system, but of the diminished cardiac energy, dilatation of the veins, and arterial anaemia.