The Purgative Action of Aloes.
Related entry: A Few Notes on Aloes
By T. AND H. SMITH.
In the 19th number of the Pharmaceutical Journal, there is published the report of a paper read by Mr. William Tilden, B. Sc., before the British Pharmaceutical Conference at Liverpool, entitled "A few Notes on Aloes." (see page 34, Amer. Journ. Pharm, Jan. 1871.) In this paper Mr. Tilden gives some very valuable information concerning the chemical properties of the drug, and we have much pleasure in bearing testimony to the ability of his researches, but, at the same time, we feel called upon to notice one or two points in his paper, on which we conceive his deductions to be erroneous.
He states that the active constituent of aloes is still unknown; that Robiquet first showed that the purgative property was not due to aloin; and he asserts that this latter substance is in complete disuse.
On these points we entertain entirely diverse opinions, and as the discoverers, and as far as we know the only manufacturers of aloin, we claim to some little knowledge of its chemical and therapeutical properties.
Mr. Tilden enumerates and describes four 'substances said to be present in aloes of the best quality, viz.:—
- Aloetin, aloesin, amorphous aloin, bitter principle of aloes.
- Crystallized aloin,
- Aloesic acid.
Of these four Mr. Tilden disbelieves in the existence of one, viz. aloesic acid, and adduces a reason why (3) resin should be related to the soluble portion of aloes. Of aloetin he remarks that it is very important as to quality, and there can be no doubt it is the product of the alteration of crystallized aloin. He regards it as a mixture of crystallized aloin, capable of recovering its crystalline condition in presence of water, and brown oxidized matter. We have many and various reasons for at present coinciding to some extent with Mr. Tilden in these remarks, but we are entirely at a loss to imagine to what substance he could attribute the purgative action of aloes, since he denies that aloin has any such effect, and yet concludes that aloes absolutely consists of that substance and products of its decomposition.
It is well known that the medicinal powers of aloes are not equal in different samples; that of two samples of the same variety, one may possess twice the purgative action of the other, and that when the varieties are different, the difference in medicinal value is in many cases even more marked.
The idea of an active principle is generally tenaciously associated with something such as strychnia or aconitia, of infinite power in small doses; but there are very many active principles, it must be remembered, the powers of which are not very many times greater than those of the drugs from which they are obtained, and in this present case, taking Mr. Tilden's results, he could not possibly expect that aloin would have more than five times the power of good aloes, inasmuch as he obtains more than 20 per cent. of the principle from the drug.
If it be admitted that aloin is the active purgative principle of aloes, one manifest advantage from using it would be that we have therein a medicine of unvarying strength, and we possess what we judge to be conclusive evidence that there is no other substance of value in aloes, and that in all cases where aloes of best quality will produce purgation, a proportionate dose of aloin will be of equal and more certain effect.
When Robiquet, in 1856, published his research on Aloetin (Journal de Pharmacie, tome xxix.), he denied that that substance (which he seems to have supposed identical with aloin) had any purgative effect. At the time we contemplated publishing a denial of this, but the late Sir James Simpson happening to visit our works, we mentioned our intention to him, when he dissuaded us, observing that medical men were quite sufficiently convinced of the power of aloin, and that he frequently prescribed it and often took it himself, and with unvarying good effect. We could name very many other medical men, of undoubted eminence, who constantly prescribe it in preference to aloes, finding that it has in no case any ill effect, and that there is never any need to give an increased dose when its use is regular and long continued. Our own personal experience bear out these statements, and our commercial transactions give most emphatic testimony that the demand is not decreasing. Since its first discovery, our manufacture has increased from a few pounds to many thousand ounces yearly, and, although we have not arrived at Mr. Tilden's gratifying result of 20 per cent., yet, by recent improvements in our manufacture, we shall be able to produce it at about two-thirds its present price, and we find the dose requisite to be aloin to aloes, as 1 is to 5. We should be happy to forward that gentleman a few doses for purpose of trial, should he wish it.—Pharm. Journ., London, Nov. 19th, 1870.
Edinburgh, November 12th, 1870.