This section is from the book "A Text-Book Of Materia Medica, Pharmacology And Therapeutics", by George F. Butler. Also available from Amazon: A text-book of materia medica, pharmacology and therapeutics.
From a general point of view there are a large number of drugs that might readily be classed as motor excitants. Thus belladonna causes increased motor excitability, and might be here included. This illustrates the futility in the present state of pharmacological knowledge of employing such widely descriptive terms. The drugs belonging to this group excite the functional activity of the spinal cord and the sympathetic nervous system. They serve to stimulate muscular contraction and the functional operations of the heart, lungs, and secretory apparatus.
It is difficult to separate by sharply defined limits the remedies having these actions and group them according to their analogous therapeutic uses. In the present group, for instance, are placed ergot and gossypium, chiefly used for their action upon the uterus, while those drugs which, although excitomotors, are employed principally for their action upon the circulatory system are placed in the group of cardiac stimulants.
The strychnine group of motor excitants contains a number of drugs that act largely on the spinal cord, increasing the activity of its reflex functions. The more important of these are nux vomica, containing strychnine and brucine; thebaine in opium; gelsemium, the gelsemine of which acts as strychnine; the gelseminine, as has already been seen, behaving like coniine; spigelia also contains a tetanizing alkaloid; physostigma contains calabarine of similar action.
Bacillus tetani contributes a tetano-toxin, with a typical strychnine-like action.
Nux vomica itself has been widely used in medicine. Our modern knowledge dates back to 1540, when it was exported from the East Indies. Many of the natives of Java and of South America have used various species of strychnos in the preparation of arrow poisons.
The most typical member of the group is nux vomica.