A striking illustration of this may be found in the natives of Hindostan. Their power of bearing the action of evacuants, particularly of blood-letting, is very limited; and the same vigorous antiphlogistic treatment which may be necessary to save the life of an Englishman, in any acute disease - in dysentery for example - would, if followed out in the Hindoo or Mussulman Sepoy, most probably so greatly exhaust the nervous energy, that a fatal result would follow. I believe that there are very few medical officers in India, who have employed blood-letting to any extent on the natives, who have not had cause, subsequently, to regret having had recourse to it.
7. Passions and Affections of the Mind have a great influence in modifying the action of medicines, particularly that of narcotics. A dose of Opium, which, under ordinary circumstances, would produce profound narcotism, would exercise no such influence if administered to a person labouring under any great mental excitement, especially anger or grief. Hope and confidence exercise a most powerfully beneficial action; and faith either in a particular medicine, or in a certain practitioner, in some instances really appears to remove mountains of apparent difficulties. How else can we account for the miraculous cures (?) effected by the bread pills and coloured water, sold under some fine-sounding soubriquet? Other circumstances which modify the action of Medicines: -
- A judicious combination of drugs is often more effectual in its operation than a single medicine, however well selected. This is particularly the case with diuretics and anthelmintics; and it is an object of considerable importance, that the practitioner should make himself well acquainted with those several combinations which either increase or diminish the action of certain remedies. Most of these combinations will be mentioned in the following pages, under their respective headings; in this place, therefore, a few examples will suffice to show the influence which this circumstance exercises. Digitalis frequently fails to act as a diuretic, until combined with the Sesquicarbonate of Ammonia, or with Squills. Jalap, Colocynth, Scammony, &c, are rendered more efficiently purgative by the addition of Calomel; and diaphoresis is more certainly induced by a combination of Ipecacuanha and Opium, than by either medicine singly. On the other hand, the purgative action of Adoes is rendered milder by the addition of Ipecacuanha; less griping by Ext. Hyoscyami; whilst it is modified by Soap, the aromatic oils, and by the alkalies. In some spasmodic affections, the operation of a cathartic is promoted by a combination with Opium; and lastly, this drug is stated to render almost inert the action of the Iodide of Potassium. In forming a combination of medicines, great care should be taken to avoid combining drugs whose action is directly opposed to each other; a diuretic and a diaphoretic for example, in one mixture, are as a rule no less incompatible therapeutically than the Nitrate of Silver and a solution of the chlorides are chemically. Do not attempt to fulfil too many indications at one time, or it is not improbable that the remedies may antagonize each other, and render your treatment perfectly inert.
2. Combination of Medicines chemically incompatible - As a general rule, it is inadvisable to prescribe in the same formula, ingredients which are chemically incompatible, unless the resulting compound be the one which the practitioner wishes to administer; thus, if the Citrate of Potash is to be given, it may effectually be done by giving, in one draught, Citric Acid and the Bicarbonate of Potash in solution; these mutually decompose each other; the Carbonic Acid is evolved, and the Citrate of Potash is obtained. It does not necessarily follow that, because the ingredients are chemically incompatible, the resulting compound is rendered inert; on the contrary, it may often happen that it is much more violent in its operation than either of the ingredients used in its formation. Here we have to call Chemistry to our aid, in order thoroughly to understand the changes which take place, and to ascertain what the compound resulting from the mixture is. Having ascertained this point, the next thing is to find out with what medicinal properties it is endowed. Many unchemical combinations are highly useful and valuable, e. g. yellow wash, a compound resulting from a mixture of Corrosive Sublimate and Aqua Calcis; black wash, that of Calomel and Aqua Calcis; and the Mistura Ferri Co., or Griffith's Mixture, in which the Carbonate of Potash and the Sulphate of Iron are mutually decomposed, a simple Carbonate of the Protoxide of Iron and the Sulphate of Potash resulting. But of all unchemical combinations, perhaps the most signally useful is that of Opium and the Acetate of Lead. These agents react chemically on each other, and produce the Acetate of Morphia, and Meconate of Lead; yet experience proves the combination to be one of the highest value in hAemorrhages and other diseases.