Tonics with Purgatives. In the exhibition of tonic medicines it is frequently essential to accompany their operation with purgation; in intermittent fevers, for instance, when attended with a redundant secretion of bile, or any obstruction of the viscera, the bark must be given in combination with some laxative, for which purpose Boerhaave has recommended Muriate of Ammonia; Mead, Rhubarb; whilst in many cases, experience suggests the propriety of selecting some of the warmer cathartics, especially the Alöetic: and I shall take this opportunity to observe, that notwithstanding the opinion so strongly expressed by Sydenham, that “to add any thing to the bark argues either ignorance or craft,” the most respectable testimony may be adduced to demonstrate the great advantages which have arisen from the various combinations of this heroic remedy. Sir George Baker has said that “there is less of reason than of severity,” in the above remark of Sydenham; for that it was found in the cure of the intermittent fever, which he describes, that, according to circumstances, sometimes the Virginian snake root, and in other cases Myrrh, were added with propriety and advantage; and, according to the experience of several practitioners, a drachm of the rust of iron, and the same quantity of the powder of black pepper, added to each ounce of bark, were the means of subduing the most inveterate agues. Formula 44 presents a combination, which we learn from Dr. Petrie’s letter to Sir George Baker, constitutes a celebrated Dutch remedy for an ague, and which was tried with success in the hospital at Lincoln, in those obstinate intermittents which prevailed in the year 1781. Hillary speaks of an epidemic intermittent at Barbadoes, in which the bark was of no avail, unless combined with saline remedies, or some of the tonic bitters. Dr. Barton has stated that Bark combined with Mercury in a small proportion, is one of the best remedies for removing the swelling of the spleen after an intermittent.
Expectorants with Diffusible Stimulants. We have seen that expectorants may be usefully associated with tonics; it sometimes occurs that these remedies require the addition of some diffusible stimulant. In certain states of Peripneumonia notha, where the powers of life are ebbing, and the lungs become inundated with viscid mucus, I have experienced the value of a combination of some stimulating expectorant and ammonia.
Antacids with Tonics. In the cure of cardialgia we have obviously two indications; to neutralize the offending acid by some chemical agent, and to correct the morbid state of the digestive functions by some appropriate remedy. See Form. 152. The same observation will apply in the treatment of certain cases of chlorosis, where cardialgia is not unfrequently a very vexatious attendant, and solicits the union of emmenagogues with antacids, or absorbents, as in Form. 99.
Lithonthryptics with Narcotics. As a palliative in calculous irritation, the union of alkalies and opium proves a valuable resource. Henbane may likewise be advantageously combined with a Lithonthryptic; for, be it remembered, that few narcotics are more efficacious in allaying nephritic irritation. (Form. 156.) We have also frequently two important indications to fulfil in the treatment of urinary concretions; where the lithic acid diathesis prevails, it will be necessary to neutralize any acidity in the first passages, and at the same time to regulate the functions of the skin; we have moreover to give tone to the digestive organs; so that, in such cases, the art of medicinal combination is well calculated to extend our resources.
In the formation of these compounds we should rarely attempt to fulfil more than two indications, although cases may occur in which it will be eligible to assail the disease with an engine of triple powers, as exemplified by Form. 52 .
In constructing, however, such complex arrangements the practitioner must of course take care that he does not fall into the error of Contraindication, and combine substances which possess properties essentially different, and which are at variance with, or directly opposed to each other; it is an error of the most serious description, and unfortunately is one of too common occurrence in the lower walks of medical practice; “crimine ab uno disce omnes.” I lately met with a country practitioner who, upon being asked by a lady whom he attended, the intention of three different draughts which he had sent her, replied, that one would warm, the second cool her, and that the third was calculated to moderate the too violent effects of either; thus it is that discredit and contempt fall upon the use of medicines, which ought only to attach to the ignorant pretenders, or designing knaves who administer them.
Having, in the commencement of this inquiry, stated that all the principles of combination, capable of practical application in the construction of extemporaneous formulæ, are exemplified in the composition of the various productions of Nature, I shall conclude the present section by shewing, that many of our most valuable vegetables owe their useful properties to the joint operation of the several distinct and different ingredients which enter into their composition. How many substances does Nature produce in the vegetable kingdom, in which the permanent tonic quality of bitterness exerts its influence in union with the transient stimulating powers of an aromatic principle? indeed there is a series of vegetable remedies of this kind: commencing with those that are simply bitter, we gradually proceed through the different species, each blending as we advance an increasing proportion of aroma, until we arrive at those in which the aromatic quality greatly preponderates. Peruvian Bark may be said to combine within itself the properties of bitterness, astringency, and aroma; a fact which suggested the probability of our being able to produce an artificial compound that might emulate the effects of Cinchona, and to a certain extent the idea appears to have been realised; for we are told by Dr. Cullen, that he frequently succeeded in the cure of an intermittent by a combination of Oak Bark and Gentian, when neither bitters nor astringents, separately, produced the least impression; and I am informed by Dr. Harrison, that in the Horncastle Dispensary, of which he was for many years physician, he never employed any other remedy for curing the ague of Lincolnshire than equal parts of Bistorta (astringent) and Calamus Aromaticus (bitter and aromatic), neither of which plants, individually, ever produced the least benefit in such diseases. Berzelius attempted to produce a compound of this description by adding to the bark of the Ash some Tormentil root and Ginger; and he observes that it acted as an excellent tonic, and that according to the experiments of his friends it seemed to cure quartan agues.[[261]] In the aromatic barks and woods, such as those of the Canella, Orange-peel, Sassafras, &c. the aromatic principle[[262]] is combined with a bitter ingredient; a union which proves of singular service in the formidable bowel complaints so common in tropical climates.
The great superiority of the hop, as an ingredient in our malt liquors, depends upon the fact of its containing within itself several distinct and independent elements of activity, which the other bitter herbs that have at different times been employed as its substitute, do not possess. The philosophy of its operation may be adduced as a striking illustration of the present subject; first, then, it contains a bitter principle, which imparts to the beverage a tonic quality and an agreeable flavour; while at the same time an aromatic ingredient adds a warm and stimulant property and modifies the bitterness; the hop, moreover, contains an astringent ingredient (Tannin and Gallic Acid), the effects of which are to precipitate the vegetable mucilage, and thus to remove from the beer the active principle of its fermentation; every attempt therefore to substitute an ordinary bitter for that of the hop must necessarily fail, unless a compound can be so artfully constructed as to contain in due proportions, the principles of bitterness, astringency, and aroma. Quassia must therefore necessarily prove but a sorry substitute; it will impart bitterness enough, but it will not be modified by agreeable aroma; and as it contains no astringent principle, it will fail in precipitating the vegetable mucilage, or gluten; in consequence of which the beer so manufactured will be in a perpetual state of fermentation until it is entirely spoilt.[[263]] Rhubarb is another medical plant which may be brought forward in elucidation of the analogies subsisting between natural and artificial combinations; in this case Nature has presented us with a singular and most important union of medicinal powers,—that of an astringent, with a cathartic property! virtues, which we might, without the light of experience, have pronounced to be incompatible with each other; and yet we find that in this instance the property of astringency never interferes with, or opposes the purgative force, since the former does not display itself unless the substance be administered in small doses; or, when given in larger ones, not until it has ceased to operate as a cathartic.