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.
Syn. White Vitriol.
In this capacity, sulphate of zinc is characterized by promptness, energy, and the production of comparatively little nausea. it operates more speedily than any other known emetic except sulphate of copper; and, though the operation is very energetic, it is soon over, and leaves little prostrating effect behind it.
Sulphate of zinc was formerly much used as an emetic, but has been almost entirely superseded by ipecacuanha and tartar emetic. Producing little of that relaxing and prostrating effect which renders tartar emetic so useful in certain cases, it would seem to be applicable, by its peculiar properties, mainly to the simple evacuation of the stomach; but here ipecacuanha has the advantage over it of greater mildness. it is much inferior to either of these medicines as a nauseant, and promoter of expectoration and perspiration.
There is, however, one condition in which its promptness and energy render it very useful. In cases of narcotic poisoning, especially by opium, it is the most efficient medicine, next possibly to sulphate of copper, in our possession; and is even preferable to that emetic, as less dangerous. I have used it often, and believe that I have never found it to fail; though I have always employed ipecacuanha as an auxiliary. The latter may be given almost indefinitely; a teaspoonful being administered at a time, and repeated several times if necessary. The dose of the former may be thirty grains; but I should hesitate to repeat it more than once, or, at the furthest, a second time, for fear that, though it may not vomit, it might possibly inflame the stomach. (See page 457.) Sulphate of zinc is also adapted to cases of poisoning by acetate of lead, in which it acts as an antidote, as well as emetic, converting the salt of lead, as far as it goes, into a comparatively inert sulphate, and itself being converted into the acetate of zinc, which performs the part of the emetic. I have seen it used with prompt success.
Another affection, in which it has been specially recommended, is pseudomembranous croup, in several cases of which it was employed by Dr. Francis, of New York, with success, after failure with ipecacuanha and tartar emetic, and under apparently hopeless circumstances. Of a solution, containing a drachm in an ounce of water, he gave a teaspoonful every ten minutes, which caused violent vomiting, and the rejection of the false membrane. (Eberle, Mat. Med. and Thérap., 4th ed.,i. 85.) This practice is well worthy of imitation in a similar condition of things. Sulphate of copper has been recommended as peculiarly efficacious; but the salt of zinc is much preferable, if it answer the purpose, as less likely to cause dangerous gastritis.
In any case requiring simple evacuation of the stomach, should ipecacuanha not be attainable, or be forbidden by idiosyncrasy of the patient, sulphate of zinc may be substituted.
The dose, under ordinary circumstances, is ten grains; in narcotic poisoning, it may be thirty grains; in either case, to be repeated at intervals of about fifteen minutes till it acts.