Senegae Radix, B.P. Senega Root.
Senega root (Senega, U.S.P.) consists of the dried root and root-stock of Polygala Senega, Linn. (N.O. Polygaleae), a plant which is widely distributed over the United States. The drug is greyish-brown or yellowish-brown, slender, frequently curved, and surmounted by a knotty crown, to which the remains of slender, aerial stems are attached. Most of the roots are distinctly keeled, and break with a short fracture. A transverse section exhibits a horny, translucent cortex, and a wood that is often irregularly developed, one or sometimes two wedge-shaped portions consisting entirely of parenchymatous tissue; the cortex contains numerous minute oil globules, but no starch. The odour of senega recalls that of wintergreen; the taste is it first sweetish, but afterwards acrid. The powdered drug is very irritating when inhaled, and imparts to water the property of frothing. Several varieties of senega root occur in commerce, viz. (1) Western Senega: this is the official variety as above described. (2) Northern Senega, obtained from P. Senega, var. latifolia. It is considerably larger than Western senega, darker in colour, less contorted, and less markedly keeled, but it has a very acrid taste, and is an active drug. (3) Southern Senega, from P. alba, Nuttall. It is smaller and more slender than Western senega, paler in colour, with normal wood. It is much less acrid in taste, and presumably, therefore, less active, and may not be substituted for the official drug. The presence of methyl salicylate does not necessarily indicate a genuine drug, as some samples of true senega do not contain it, while it is contained by others which are not genuine. The amount present appears to increase as the drug is kept, probably due to a gradual decomposition of a glucoside. On incineration, senega root yields about 4 per cent. of ash.
Constituents.—The chief constituents of the root are the two glucosidal saponins, senegin and polygalic acid, which resemble, but are riot identical with, quillaja-sapotoxin and quillajic acid. The drug is said to contain other glucosides which, however, have not yet been sufficiently investigated. Polygalic acid is sternutatory, and produces frothing, while senegin is decidedly toxic. The odour of the drug is due to the presence of a small quantity of methyl salicylate. Senega root also contains about 5 per cent. of fixed oil.
Action and Uses.—The action of senega is attributed to its glucosidal saponins, which are irritants to the gastric mucous membrane, and give rise to a reflex secretion of mucus in the bronchioles. It is employed as a stimulating expectorant in chronic bronchitis. The drug is administered chiefly as Infusum or Decoctum Senegae and Tinctura Senega,, and is usually given with other expectorants, such is ipecacuanha, squill, and ammonium carbonate. It is not absorbed into the system.
- Fluidextractum Senegae, U.S.P.—FLUIDEXTRACT OF SENEGA.
- Senega, in No. 40 powder, 100; solution of potash (5 per cent.), 3; alcohol, (71 per cent.), sufficient to produce 100. May be used in place of tincture of senega for its expectorant properties. Average dose.—1 mil (15 minims).
- Infusum Senegae, B.P.—INFUSION OF SENEGA.
- Senega root, in No. 10 powder, 5; distilled water, boiling, 100. Infuse the drug in the water for 30 minutes, in a covered vessel and strain. Infusion of senega is a vehicle for diaphoretics and expectorants. Dose.—14 to 30 mils (½ to 1 fluid ounce).
- Infusum Senegae Concentratum, B.P.C.—CONCENTRATED INFUSION OF SENEGA.
- A product closely resembling infusion of senega is obtained by diluting 1 part of this preparation with 7 parts of distilled water. Dose.—2 to 4 mils (½ to 1 fluid drachm).
- Liquor Senegae Concentratus, B.P.—CONCENTRATED SOLUTION OF SENEGA.
- Senega root, in No. 20 powder, 50; alcohol (20 per cent.), 84; alcohol (45 per cent.), 42. Mix the alcohols, moisten the drug with 26 of the mixture and pack in a percolator; after an interval of three days, percolate with 100 of the mixture, which should be added in 10 equal portions at intervals of twelve hours, and continue the percolation, if necessary, with more of the alcohols mixed in the same proportions, in order to produce 100 by volume. This preparation may, with advantage, be replaced by Infusum Senegae Concentratum. Dose.—2 to 4 mils (½ to 1 fluid drachm).
- Syrupus Senegae, U.S.P.—SYRUP OF SENEGA.
- Fluidextract of senega, 20; syrup, 80. A gastric expectorant for use in chronic bronchitis. Average dose.—4 mils (1 fluid drachm).
- Tinctura Senegae, B.P.—TINCTURE OF SENEGA.
- Senega root. in No. 40 powder, 20; alcohol (60 per cent.), sufficient to produce 100. Add 20 of the alcohol to the drug to moisten it, and proceed with the percolation process. Tincture of senega is employed is a stimulating expectorant in chronic bronchitis, usually combined with other expectorants. Dose.—2 to 4 mils (½ to 1 fluid drachm).