On Syrup of Senna.

Botanical name: 


This syrup, which was officinal in the U. S. P. of 1850, was omitted in that of 1860, the authors, perhaps, thinking that its place might be supplied by the fluid extract; but, as the syrup has been so long known and used, not only in professional but also in domestic practice, there still exists for it a lingering demand, which is likely to continue. To supply this demand the pharmacist is compelled to keep the syrup constantly on hand; and, as the formula of the U. S. Pharmacopoeia of 1850 yielded rather an uncertain preparation, which was very liable to spoil if long kept, I thought I would offer a formula for its preparation which I have used for several years, and which will afford a reliable and permanent syrup. As an evidence of this, I have samples of it which have kept for nearly three years unaltered. The demand for the syrup in some localities being limited, and the fact of its being an unstable preparation as made by the late officinal formula, some pharmacists have been led to the habit of making it, in small quantities, as needed, from the fluid extract; but this practice should not be encouraged, and it is only when the pharmacist makes correctly his own fluid extract, and is sure of its reliable quality, that this mode of preparing the syrup should ever be employed.

The following is the process which I have adopted:

Rx. Pulv. Sennae, No. 60, ℥ij troy,
Pulv. Foeniculi, No. 60, ℥j troy,
Sacchar. alb., sifted, ℥ix troy,
Glycerinae, f℥iv troy,
Alcohol. dil., sufficient quantity.

Mix the powders, and, having moistened the mixture with dil. alcohol, pack it firmly in a glass funnel prepared for percolation, and gradually pour diluted alcohol upon it until sixteen fluidounces are obtained, or until the mixture is exhausted. Set aside in a shallow dish, in a warm place, the first four fluidounces which pass, to evaporate spontaneously to two fluidounces. To the remainder of the percolate add the sugar, and evaporate it in a water-bath, at a temperature not exceeding 160°, with frequent stirring, until the whole measures, when cold, ten fluidounces. To this add the glycerin and reserved portion, mix well, and strain through muslin.

If the percolation is managed with care, the reserved percolate will contain at least four-fifths of the active properties of the senna and the aromatic qualities of the fennel. This, then, being evaporated spontaneously, and the remaining portion protected by the sugar from the injurious effects of the atmosphere during the concentration, furnishes a syrup embodying the virtues of the senna and fennel unimpaired.

One serious objection to the process of the U. S. P., 1860, was the prolonged exposure to heat necessary to reduce the syrup to the "proper consistence," during which a great portion of the volatile oil of the fennel must have been dissipated, and the purgative properties of the senna in a measure diminished, while at the same time its griping tendency was promoted.

This same objection applies with double force to the present British process, presented in the last edition of the U. S. D. In that process about one hundred fluidounces of infusion are directed to be reduced, by evaporation, to ten fluidounces. It can well be imagined what influence this torture, as it were, would exert upon the medicinal properties of the senna, if they are at all vulnerable to the effects either of heat or atmospheric oxygen.

Another very objectionable feature of the British syrup is that of its strength, which is about four times as great as that of the U. S. P., 1850. Upon this point, Dr. Wood, in his comments upon the process in the U. S. Dispensatory, very properly makes the following remarks: "The present British syrup, which has superseded the former syrups of the London and Edinburgh colleges, differs from them, as well as from that of the U. S. Pharmacopoeia of 1850, very greatly in strength, so that in prescribing it physicians accustomed to the doses of the former syrups must be on their guard not very seriously to overdose their patients." These remarks are equally applicable to its use in domestic practice; and, since it is chiefly given to children, its administration in excessive doses might be attended by mischievous results.

As the British process is the only one that the late edition of the U. S. Dispensatory offers to American pharmacists for their guide in the preparation of this syrup, and as it has an established reputation, they are obliged to keep it in stock, I think it highly important that it should be reinstated in the next edition of our Pharmacopoeia, and a good working formula given, which will yield a reliable and at the same time a permanent preparation, corresponding in strength with that of the U. S. P., 1850.

The proportions of senna and fennel, in the formula given above, correspond precisely with those of the formula of our late Pharmacopoeia; but in the latter process the volatile oil of the fennel was only partially extracted by the aqueous menstruum, and a portion even of that must have afterwards been lost in the evaporation of the syrup. This, therefore, necessitated the employment of a large excess of the fennel.

Now, since in the process proposed by me the aromatic properties of the latter are entirely extracted, and there is but slight if any loss by subsequent evaporation, I think that the quantity of the fennel might with propriety be reduced one-half, and still be sufficient to answer all purposes for which the aromatic is employed, without in the least impairing the virtues of the syrup.

It will be observed that in the above formula I have employed diluted alcohol as the menstruum in the place of water, which has heretofore been exclusively used. This has not been done unadvisedly, but from a strong conviction that the alcoholic menstruum possesses superior advantages over that of the aqueous one; for, by means of it there is obtained directly, by the process of percolation, a more highly concentrated solution, obviating the long and tedious application of heat necessary to reduce the aqueous solution to a proper strength, thus more than counterbalancing whatever advantages, if any, therapeutically, the aqueous may have been supposed to possess over the spirituous solvent.

It has doubtless been owing to the tedious and inefficient methods heretofore in vogue in the manufacture of this syrup, that has led to the discarding of its formula from our Pharmacopoeia, and to its partial disuse in professional practice. It is certainly, however, when properly prepared, an efficient, useful and convenient preparation for children, for whom it was originally intended; and, if a reliable and satisfactory formula, such as we present, should be adopted in its manufacture, its restoration to its former place in professional favor would doubtless follow.

Philadelphia, September, 1871.

The American Journal of Pharmacy, Vol. XLIII, 1871, was edited by William Procter, Jr. (Issues 1-4) and John M. Maisch (Issues 5-12).