On the Preparation of Suppositories.
By WILLIAM G. EWING.
(An Inaugural Essay.)
I have read most of the articles that have appeared in the Amer. Journ. Pharmacy for several years, upon the subject of suppositories and have gained many valuable suggestions from Messrs. J. B. Moore, Chas. L. Eberle and others; but I have fallen upon a process not alluded to by any of them, that greatly facilitates this tedious, and sometimes very difficult, and troublesome class of prescriptions. The plan I have adopted is as follows:
First, procure a large, coarse tin grater—such as may be had of any tinner—and with it grate the cacao butter into a coarse powder, pass through sieve No. 20, and put it into a wide mouth bottle ready for use; next, take some pure white wax, grate, sift, bottle, and set it aside in the same manner as above. The fragments that will not pass through the sieve can be melted, and grated again after cooling. With these two substances on hand, the prescriptionist is prepared for any formula in the suppository line.
The management of the melting point of suppositories has been a matter of great difficulty, annoyance and delay, varying as it does with the seasons; but with this (grated material) we have a ready means of regulating it at will; for if the mass should be too hard—as in winter—the addition of a little olive oil will be found advantageous; or, if too soft—as in summer—the addition of the grated wax will bring it to the right consistence. In addition to the above ready means of controlling the melting point, it has the advantage of being much more easily manipulated. For instance, take the following suppository from the U. S. Dispensatory, 13th edition, viz.:
|Rx||Tannic Acid||grs. 36.|
|Benzoated Lard||grs. 44.|
|White Wax||grs. 10.|
|Oil of Theobroma||grs. 90.|
The directions are to melt the wax and oil of theobroma, with a gentle heat, and add the tannic acid and benzoated lard, previously rubbed together in a mortar, and mix all the ingredients thoroughly; pour the mixture, while it is still fluid, into suitable moulds of the capacity of 15 grains, or the fluid mixture may be allowed to cool, and then divided into 12 equal parts, each of which shall be made into a conical, or other convenient form for a suppository.
The above formula is easily expressed, but not so easily complied with in all cases, owing to the variable nature of the oil of theobroma, and also to the temperature of the season; but, accepting it as it stands, the advantage of the grated wax and cacao butter is very perceptible, since instead of melting one portion together, and rubbing the other portion in a mortar as prescribed, the whole may be at once mixed and rubbed together in a mortar, forming a plastic mass as easily rolled into lengths and divided as an ordinary pill mass; and each piece formed by the fingers into a conical shape, or, if desirable, pressed into suitable moulds previously dusted with lycopodium, as suggested by Mr. J. B. Moore. The following is a copy of a far more difficult prescription, that was brought to me by a patient to be filled one very warm night.
|Rx||Carbolic Acid||grs. xxx.|
Mix and make suppositories No. 10.
Here the prescriptionist is in a dilemma. If the carbolic acid and cacao butter are melted together they will not solidify on cooling; if wax be melted with the mixture, considerable time is occupied in adjusting the proportions, as it is necessary to test it by allowing portions to cool from time to time, and adding wax by degrees until the proper consistence is attained; meanwhile the carbolic acid is evaporating, and the efficacy of the suppositories being impaired. Having the grated materials at hand, and no other recourse but to add a sufficiency of wax, it was immediately and easily done by rubbing it in until the proper consistence was attained, the amount of wax required being 70 grains; the prescription was much more quickly dispensed than by any of the usual methods, and as there was no heat employed in the process there could have been no evaporation of the carbolic acid. In the above case, the grated wax and carbolic acid were first well rubbed together, and the cacao butter added last.
As no allowance was made for the addition of wax, the size of each suppository was slightly increased, (though not materially) and, as each contained the exact proportion of its active ingredient, the design of the prescription was executed. The weight of each suppository might have been left unchanged by omitting enough cacao butter to balance the wax that was added.
It is needless to repeat examples, though many difficult ones might be given from actual experience; it is sufficient to state a few general principles.
When dry substances are prescribed, they should be reduced to fine powders (if not already so) then thoroughly incorporated with the grated cacao butter, and rubbed in a mortar until the mixture becomes a plastic mass easily rolled into lengths, divided and formed into suppositories. Should moist substances, such as extracts or any articles not dry, be prescribed, they may be rubbed first with about an equal bulk of the grated cacao butter, and afterwards readily combined with the remaining ingredients.
As a general rule, all substances used in medicating suppositories must be either in the state of a fine powder, or a uniform paste; the prescriptionist must decide upon the more easily attainable state.
The advantages of using the cacao butter in the grated state are numerous. It furnishes the means of easy manipulation, of readily adjusting the melting point, of avoiding the delay of melting and cooling, and the use of ice which is not always procurable, of thorough and perfect incorporation of its ingredients, of exactness with which the mass may be divided; besides the satisfaction it gives the prescriptionist of knowing that no separation nor subsidence of any of its ingredients can possibly take place, which certainly cannot be felt when the substance is melted and moulded.