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.
In reference to the administration of nux vomica and its preparations, a few preliminary observations regarding certain peculiarities in the operation of the remedy are necessary, in order properly to regulate its exhibition.
In the first place, it has been often noticed that the system becomes less rapidly habituated to this remedy than to most others, and that consequently it is not requisite, in order to maintain a given impression, to go on increasing the dose, as is necessary with the narcotics. After it has been ascertained how much is required to produce the characteristic effects, the dose may often be continued without augmentation for a long time. I have had patients for several weeks, if not for months, under the use of strychnia, without being able to increase the dose, unless at the risk of inducing troublesome muscular contractions. Nevertheless, it is probably only in degree that nux vomica differs from other medicines in this respect; and if, after having given evidence of its action, it should at length cease to do so, the dose should be cautiously increased up to the amount requisite for sensible effect.
It occasionally happens that, instead of becoming less susceptible to the influence of the medicine with its continued use, the system is apparently more so, and the same doses cannot be borne as at first This can be explained, without the necessity of considering nux vomica as an absolute exception to the otherwise almost universal rule. In the event referred to, the medicine may be conceived to have induced a positive irritation of the spinal marrow, perhaps in consequence of an existing predisposition, which irritation, having thus been set on foot by it, will continue altogether independently of its further influence, just as if it had been induced by cold, which does sometimes give rise to a similar condition, as in idiopathic tetanus. This irritation may continue for several days, giving rise to phenomena similar to those produced by the medicine, which seems therefore to sustain its action for a long period, though really at the time quite inoperative. In this condition, a further dose would aggravate the irritation, and seem, therefore, to be operating on an increased susceptibility: whereas the susceptibility might remain unaltered, or possibly even be lessened. The occasional result, therefore, above referred to, must be considered as exceptional, and by no means authorizing the conclusion, as a law of the action of nux vomica, that the longer it is given the greater is the susceptibility to its action.
A second very important consideration is the vast difference of susceptibility to its influence in different individuals. In this respect, though not quite peculiar, for there are several substances of which the same fact holds true, and some even to a greater extent than nux vomica, yet it differs so much from ordinary medicines that the greatest caution is requisite in regulating the dose, i have known a lady to be thrown into violent and even alarming spasms, almost threatening suffocation, by one-twelfth of a grain of strychnia : and instances have already been referred to of death from fifteen grains of the powder, and three grains of the extract of nux vomica; while Pereira once gave to a patient a grain and a half of the alkaloid, which was repeated several times, before the symptoms indicating that the system was affected came on. Though he began with smaller quantities, and gradually increased to that mentioned, and although no serious consequences ensued in the case, yet he states that subsequent experience had convinced him that so large a dose was dangerous. With our present knowledge of the action of this medicine, I do not think that a practitioner would be justifiable in administering such quantities, however cautiously they may have been reached. I have noticed the extreme susceptibility, above referred to, most frequently in nervous females-.
A third point worthy of attention is the question whether nux vomica is cumulative; that is, whether, alter having been given for some time in repeated doses, at the ordinary intervals, without any apparent effect, it can ever break forth suddenly with the full influence of the accumulated doses, and with danger to life. It has generally been thought not to be so; and no danger has been apprehended upon this score. But a case has been recorded by Dr. Pereira, which shows that the use of it is not so exempt from this danger as had been supposed. Strychnia was given to a man first in the dose of one-eighth of a grain, then of one-quarter, and finally of half a grain, in each instance being repeated three times a day, and the last dose was continued many days without perceptible effect. At length he was seized suddenly with violent spasms, and died with asphyxia in a very short time. (Mat. Med., 3d ed., p. 1497.) Un-combined strychnia is of extremely slight solubility in cold water, while in acidulated water it is readily dissolved. It might happen that acid in the primae vise should be wanting for a time, and the strychnia thus remain undissolved and accumulating; but at length the gastric juice, • reacquiring its normal acidity, might dissolve the whole at once, and enable it to be absorbed. The effects in the above case may thus be conjecturally explained. The lesson deducible from it is never to venture upon so large a dose; as present impunity, even though lasting for many days during the administration of the medicine, affords no certain guarantee against ultimate danger.
From all that has been stated above it is to be inferred that, in using any of the forms of nux vomica, we should begin with a very small dose, especially in persons of great nervous irritability, as nervous females and young children, and increase by minute increments, and at intervals not shorter than a day or two, until we have ascertained the active dose, and then increase no further, but rather fall back somewhat, or suspend for a time, especially if the symptoms should be of a rather decided character. If the first dose produce observable effect, it should not be repeated till these effects have ceased, and then in diminished amount. In no case should the quantity be increased, however cautiously the augmentation may be conducted, to an amount adequate to the destruction of life in ordinary persons.
When the medicine is administered as a tonic simply, it may be pushed, with the precautions just mentioned, to the point of observable effect on the system, and then diminished, so as to be maintained just within that point.
The following are the different forms which may be resorted to for exhibition.
The Powder. Nux vomica is not readily reduced to fine powder, and from this cause, as well as from its extremely bitter taste, and its uncertainty as regards strength, is seldom administered in that form. The dose is five grains three times a day, to be gradually increased till its effects are produced; but in no case should it be pushed beyond fifty grains; and it would be better to stop short at twenty or thirty grains. The dose of the bean of St. Ignatius should not be more than one-third that of nux vomica. Either of these may be given in pill if deemed advisable.