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.
After the crystallization of all the sulphate of quinia that can be obtained in that form, in the process for preparing the salt, there is left behind a mother liquor, by the evaporation of which a dark amorphous substance is obtained, which was formerly recognized by our Pharmacopoeia under the name of impure sulphate of quinia. This had been used, before being thus offieinally recognized, by the late Dr. Samuel Emlen, of Philadelphia, and by the author, with all the effects of the pure sulphate in the case of intermittents, though requiring to be given in about double the dose. It was supposed to consist of sulphate of quinia with a little sulphate of cinchonia, and colouring impurities. From the want of precise characters by which it could be recognized, it has been abandoned in the recent revisions of the Pharmacopoeia.
Serturner supposed that, in this residuary matter, he had found a new alkaloid, which was named quinoidin from its resemblance to quinia. According to Liebig this new alkaloid has the same composition as quinia, from which it differs only in being uncrystallizable, and imparting this same property to its salts. He therefore named it amorphous quinia. Pasteur ascertained that what was called quinoidin by Serturner, and amorphous quinia by Liebig, consists usually of two alkaloids, one called by him quinicia, because derived from quinia, the other cinchonicia, from the same relation to cinchonia. They are probably mainly the result of the process for extracting the alkaloids; the heat employed having the effect of modifying the state of quinia and cinchonia, as the same agency converts crystallizable into uncrystallizable sugar.
The substance called quinoidin in commerce, containing the amorphous quinia of Liebig, is obtained by precipitating the mother liquor of sulphate of quinia above referred to, by means of an alkaline carbonate, which decomposes the sulphates contained in it, and throws down the uncombined alkaloids. By repeated solution and precipitation, the alkaline matter may be obtained quite pure, and, in this state, consists of the two alkaloids quinicia and cinchonicia, together with whatever other organic alkali may have existed in the bark, as cinchonia, and possibly sometimes quinia, quinidia, and cinchonidia. When pure, it is an excellent preparation, and may be employed, in all cases, as a substitute for sulphate of quinia, in about the same dose.
Cinciionae Sulphas. U. S. This was first recognized as officinal in the present U. S. Pharmacopoeia. It may be made by directly combining its ingredients, or by crystallization from the mother waters of sulphate of quinia, after this salt has been wholly separated from them. It is in short, oblique, shining, prismatic crystals, with dihedral summits, which melt at 212° P., are soluble in 54 parts of cold, and a much smaller proportion of boiling water, are readily dissolved by alcohol, and scarcely soluble in ether, and have a very bitter taste. The salt is either a sulphate or disulphate, according to the opinion which may be adopted as to the equivalent of cinchonia; and, like the sulphate of quinia, may be converted into a more soluble salt by combination with an additional equivalent of acid It has been abundantly proved to have the therapeutic virtues of sulphate of quinia, though somewhat feebler. A general result of observation has been that it is less apt than sulphate of quinia to occasion buzzing in the ears, deafness, and disturbance of vision, at least in the same dose; though, according to Bouchardat, it produces, even in smaller doses and more certainly than that salt, a peculiar headache, rather severe, which is seated specially in the anterior part of the head, and is attended with a remarkable feeling of compression. (Ann. de Therap., 1857, p. 126.) To obtain the same effects from it, the dose should be about one-third, or at least one-quarter, greater than that of the salt of quinia.
Cinchonidiae Sulphas. This is the salt which a few years since first came into notice under the name of sulphate of quinidia, which name is commercially still applied to it. The fact is that, as sold, it is usually complex, consisting of the two sulphates of cinchonidia and quinidia, though with a great predominance of the former. It is obtained for use from the barks which most abound in cinchonidia, by the same process as that employed in the preparation of sulphate of quinia from Calisaya bark. Like the analogous salt of quinia, this is considered by some as a neutral, by others as a subsalt, and by the latter would be called a disulphate. It is in long, silky, acicular crystals, soluble in 130 parts of cold and 16 of boiling water, readily soluble in alcohol, but nearly insoluble in ether; and by these properties may be distinguished from the corresponding salt of quinia. It has the same effects as the sulphates of quinia and cinchonia, and may be employed in the same doses as the latter salt. That it is little if at all inferior, in the treatment of intermittent fever, has been abundantly proved by the trials made with it by Dr. J. S. Dorsey Cullen, in the Almshouse Hospital of Philadelphia (Am. Journ. of Med. Sci., N. S., xxix. 81); and those of Dr. Geo. L. Upshur, surgeon to the U.S. Marine Hospital at Norfolk (Med. Examiner, N. S., x. 740). From fifteen to thirty grains were employed between the paroxysms.
I am not aware that the proper sulphate of quinidia is used as a distinct preparation. It is contained occasionally in the sulphates of the other cinchona alkaloids, and is probably identical in therapeutic influence with sulphate of quinia, or so nearly so as to render its presence, in small proportions, of no practical importance.
Peruvian bark owes its special virtues to the peculiarity of its active tonic principles. Besides nectandra or bebeeru bark, recently admitted into the officinal catalogues, there are several substances of minor importance, supposed to possess peculiar virtues, which, if the claim be admitted, must rank in the same category. Among these are the dogwood and willow barks. It is true that these have a portion of tannic acid associated with the bitter principle; but it is not to this that the remedial effects ascribed to them, and to which they mainly owe what reputation they possess, can be attributed, any more than the characteristic remedial properties of Peruvian bark can be attributed to the tannic acid which it also contains. If they have special virtues, these reside, in all probability, in their bitter principle; and the medicines, therefore, may be appropriately considered here.