This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol1", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
This is an aqueous extract of opium, and of course consists exclusively of the principles soluble in water. Opium contains ingredients insoluble in water, which, however, it yields to an alcoholic solvent, either vinous or distilled; and, as these principles may possibly be not without some influence upon the system, the effects of the opium may be somewhat modified in the extract, and different from those obtained from opium itself, its tinctures, or the wine. Hence this preparation is supposed to agree with certain individuals, with whom opium and its other preparations disagree. It has the advantage also of affording a ready means of preparing a solution of the active matter of opium in water, which is sometimes desirable, particularly for application to the eye, and other external inflamed surfaces, and for injection into inflamed or irritated mucous passages, as the rectum, urethra, or vagina, in all of which cases. the stimulant properties of the tincture, derived from the alcohol it contains, are contraindicated. The dose is one-half that of opium.
In dysenteric cases, an injection of the extract of opium, dissolved in water, will sometimes be retained, and afford relief, when laudanum would be rejected; and it is not impossible that the same remark may be true of its use in irritable states of the stomach. A solution of the extract, in the proportion of from one quarter to one-half of a grain to the fluidounce, is sometimes administered in the form of spray, to relieve cough; being thrown into the air-passages by means of the atomizer.
In a former edition of this treatise, it was suggested that an Elixir of Opium might be prepared from the watery extract, by treating it with diluted alcohol, using only half as much of the extract in proportion as there is of opium employed in the preparation of the tincture. An elixir thus made would have the same strength as laudanum, and would be destitute of whatever matter, insoluble in water, alcohol may extract from opium. This suggestion has been more than met by the Deodorized Tincture of Opium of the present U. S. Pharmacopoeia.