Pharmacologia / Fourth American, from the Seventh London Edition

by John Ayrton Paris

Explanation of the Key Letters.

The Modus Operandi of the different elements of each formula is designated by a Key Letter, or Symbol, which is printed in a different type, (thus B) and placed in the margin opposite to each. This letter refers to a corresponding one in the Synopsis, and thereby shews the division containing an exposition of the principles upon which the operation of the ingredient is supposed to depend.

Two or more Key Letters denote that the element against which they are so placed has several modes of operation, whilst the order in which the letters succeed each other, serves to shew the relative importance of them.

Where any one of the letters is small, i. e. not a capital, it denotes that the operation which it is intended to express is only incidental to, or subordinate in, the general scheme of the combination.

When any number of elements are included within a vinculum or bracket, it is intended to shew that they operate but as one substance, or, that the virtues of each are not independent of the other; in this case the Key Letter within the bracket expresses upon what principle this unity depends, whilst that on the exterior shews the action of such a combination upon the base, or the part which it performs in the general scheme of the Formula.

Let us exemplify it by a reference to Formula 78 which presents us with a Purgative, in conjunction with a Stimulant. The base is Aloes, which is succeeded by Scammony, and Extract of Rhubarb; these substances appear by the bracket, to act in unison, a concurrence which the interior letter B shews to depend upon their being Similar Remedies; the letter also on the exterior shews that its operation upon the base depends upon the same principle. We next come to powdered Capsicum, and Oil of Cloves; these ingredients are also shewn by a bracket to act in unity, and the letter B in the interior, denotes that it is in consequence of their possessing a similar mode of action, whilst the letter G on the exterior, announces that they act in the general scheme for the purpose of fulfilling a second indication; at the same time the smaller letter e informs us that the combination likewise acts as a corrector of the base.[^[315]]

A SYNOPSIS
OF THE
Principles of Combination,
AS INVESTIGATED IN THE PRECEDING PAGES,
ARRANGED IN A TABULAR FORM
SO AS TO AFFORD THE STUDENT AN EASY
REFERENCE TO THE KEY LETTERS.

A Synopsis of the Principles of Medicinal Combination.

OBJECT I.
TO PROMOTE THE ACTION OF THE BASIS.

Key Letters. A A.—By combining the several different forms, or preparations of the same Substance. B B.—By combining the Basis with Substances which are of the same Nature, i. e, which are individually capable of producing the same effects, but with less energy than when in combination with each other. C C.—By combining the Basis with Substances of a Different Nature, and which do not exert any Chemical influence upon it, but are found by experience, or inferred by analogy, to be capable of rendering the stomach, or system, more susceptible of its action.

OBJECT II.
TO CORRECT THE OPERATION OF THE BASIS, BY OBVIATING ANY UNPLEASANT EFFECTS IT MIGHT BE LIKELY TO OCCASION, AND WHICH WOULD PERVERT ITS INTENDED ACTION, AND DEFEAT THE OBJECT OF ITS EXHIBITION.

D A.—By CHEMICALLY neutralizing, or MECHANICALLY separating, the offending ingredient. E B.—By adding some substance calculated to guard the stomach, or system against its deleterious effects.

OBJECT III.
TO OBTAIN THE JOINT OPERATION OF TWO, OR MORE MEDICINES.

F A.—By uniting those Medicines which are calculated to produce the SAME ULTIMATE RESULTS, but by modes of operation totally different. G B.—By combining Medicines which have entirely different powers, and which are required to obviate different symptoms, or to answer different indications.

OBJECT IV.
TO OBTAIN A NEW AND ACTIVE REMEDY, NOT AFFORDED BY ANY SINGLE SUBSTANCE.

H A.—By combining Medicines which excite different actions in the stomach and system, in consequence of which NEW, or MODIFIED RESULTS are produced. B.—By combining substances which have the property of acting CHEMICALLY upon each other; the results of which are— I   a. The Formation of New Compounds. K   b. The Decomposition of the Original Ingredients, and the developement of their more active elements. C.—By combining Substances, between which no other change is induced than a diminution, or increase in the Solubility of the principles in which their Medicinal virtues reside. L   a. By the intervention of Substances that act CHEMICALLY. M   b. By the addition of Ingredients whose operation is entirely Mechanical.

OBJECT V.
TO AFFORD AN ELIGIBLE FORM.

N   a. By which the Efficacy of the Remedy is enhanced. O   b. By which its Aspect or Flavour is rendered more agreeable, or its mode of administration more convenient. P   c. By which it is Preserved from the spontaneous decomposition to which it is liable.