This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol2", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
These are medicines which have the special property of promoting uterine contraction. I object to the terms abortives (abortiva) and ecbolica (ecbolica), implying the power of producing abortion, as suggestive, not of any characteristic physiological property, but of a too frequent misapplication of these medicines.
It is not their characteristic property to cause abortion. Substances which produce that effect may, and often do act, quite independently of any property of directly promoting uterine contraction. Whatever agitates, shocks, or violently irritates the pregnant uterus may occasion miscarriage. The uterine muscles contract, not through the immediate influence of the agent upon the function, but in consequence of some other effect produced by it. Thus, the drastic cathartics, the more energetic of the irritant diuretics, and the stimulant emmenagogues occasionally bring on abortion, either by a sympathy of the womb with a violent impression elsewhere, or through a vascular irritation or inflammation of its membrane or tissue, reacting on the muscular fibres. These abortives are all more or less violent in their action; and their influence, if successful, may always be considered as endangering the life both of the female and the offspring.
Nor do I include in this class those local measures, which, after delivery, assist in promoting the contraction of the womb; such as external friction, irritation applied to the internal surface of the organ, cold, etc.
The medicines now under consideration operate directly upon the muscular function of the organ. They act through the circulation, and may affect the muscular fibres either by direct contact with them, or, what appears to me more probable, through the nervous centres which control their movements.
Their therapeutic applications, in reference specially to their distinguishing property, are not numerous, and will be most conveniently considered under the particular member of the class, which is the most prominent among them. it might be supposed that their abortive agency would be powerful and effective. But it is not so; for there appears to be some relation between their peculiar property, and the susceptibility of the motor function, which counteracts their influence under circumstances forbidding their use. They cannot at all be depended on, with a view to the expulsion of the foetus, when yet quite immature. The individual motor stimulants of the uterus are very few. Perhaps, indeed, there is only one of which this property is incontestably established. There are others, however, which appear to have some claim to a position in the class, and will receive due attention.