Hops (Humulus, U.S.P.) are the dried fruits (strobiles) of Humulus Lupulus, Linn. (N.O. Urticaceae), collected from cultivated plants. The hop is a climbing plant growing in Europe generally, but largely cultivated in England, Germany, Russia, California, etc. It is dioecious, but the pistillate plant only is cultivated. The hops are picked when they are fully developed, dried in kilns, and frequently exposed to the fumes of burning sulphur. They are then packed into bales known as "pockets." The strobiles are about 3 centimetres long, ovoid in shape, and consist of a number of imbricated yellowish-green membranous bracts and stipules attached to a hairy zigzag axis. Each of the bracts enfolds at the base a small fruit (achene), both fruit and bract being sprinkled with yellow, translucent glands. Fresh hops possess a bitter, aromatic taste, and a strong, characteristic aromatic odour. The latter, however, changes and becomes distinctly unpleasant as the hops are kept. This change is ascribed to oxidation of the soft resin with production of valerianic acid. On account of the rapid change in the odour of hops, the recently dried fruits should alone be used; these may be recognised by the characteristic odour and distinctly greenish colour. Hops yield about 7 per cent. of ash.
Constituents.—The aromatic odour of hops is due to volatile oil, of which they yield about 0.3 to 1.0 per cent.; it appears to consist chiefly of the sesquiterpene humulene. Petroleum spirit extracts a soft resin (7 to 14 per cent.), and ether a hard resin. The petroleum spirit extract contains the two crystalline bitter principles, α-lupamaric acid (humulone), and β-lupamaric acid (lupulinic acid). These bodies are chiefly contained in the glands. The leafy organs contain about 5 per cent. of tannin, which is not a constituent of the glands.
Action and Uses.—Hops have the action of the aromatic bitters. The infusion is employed as a vehicle especially for bitters and tonics; the tincture is stomachic and is used to improve the appetite and digestion. Both preparations were formerly believed to be sedative and were given in nervousness and hysteria, and at bedtime to induce sleep. Hops are also made up into pillows on the supposition that they induce sleep; any such action must be attributed to suggestion rather than to any effect of the volatile principles. Hop poultices are sometimes used for application to inflammatory swellings. Preparations of hops are incompatible with mineral acids and metallic salts.
Dose.—1 to 2 grammes (15 to 30 grains).
- Extractum Lupuli, B.P., 1885.—EXTRACT OF HOPS.
- Hops, 1 pound; rectified spirit, 1 1/2 pints; distilled water, 1 gallon. Macerate the hops with the spirit for seven days; then press, filter, and distil off the spirit, leaving a soft extract. Boil the marc with the water for one hour; then press, strain, and evaporate on a water-bath until a soft extract is obtained. Finally, mix the two extracts, and evaporate at a temperature not exceeding 60°, until a mass of pilular consistence is obtained. Extract of hops is used in pills as a tonic and bitter, in a similar manner to extract of gentian. Dose.—3 to 10 decigrams (5 to 15 grains).
- Infusum Lupuli, B.P.—INFUSION OF HOPS.
- Hops, freshly broken, 5; distilled water, boiling, 100. Infuse the drug in the water for fifteen minutes, in a covered vessel, and strain. infusion of hops is used as an aromatic bitter and vehicle for tonics; also as a mild sedative. Dose.—30 to 60 mils (1 to 2 fluid ounces).
- Infusum Lupuli Concentratum, B.P.C.—CONCENTRATED INFUSION OF HOPS.
- A product closely resembling infusion of hops is obtained by diluting 1 part of this preparation with 7 parts of distilled water. Dose.—4 to 8 mils (1 to 2 fluid drachms).
- Tinctura Lupuli, B.P.—TINCTURE OF HOPS.
- Hops, 20; alcohol (60 per cent.), 100. Macerate for seven days, and complete the maceration process. Dose.—2 to 4 mils (1/2 to 1 fluid drachm).
Lupulin consists of the glandular trichomes separated from the strobiles of Humulus Lupulus, Linn. (N.O. Urticaceae). It is also official in the U.S.P. The glands, which are distributed over the bases of the bracts, over the fruits, and, to a less degree, over the stipules, may be separated by shaking and beating the hops. The drug occurs in a granular, brownish-yellow powder, with the strong odour and bitter, aromatic taste characteristic of hops. Examined under the microscope, the glands are seen to be more or less rounded or broadly ovoid, and to measure from 140μ to 200μ in diameter; the upper portion is bounded by a thin cuticle, the lower by a single hemispherical layer of cells. They readily burst on the application of slight pressure, and discharge their granular oleoresinous contents. Lupulin should contain not more than 40 per cent. of matter insoluble in ether, and should yield not more than 12 per cent. of ash on incineration. Commercial lupulin is often of very inferior quality, and may consist of the sifted sweepings from the floors of hop kilns. A dark colour and disagreeable odour indicate an old drug, the latter character being attributed to the presence of valerianic acid, which is produced gradually from the resin; the ash may rise to .25 per cent., or even more, while the percentage insoluble in ether may be more than 40.
Constituents.—The chief constituent of lupulin is about 3 per cent. of volatile oil, which consists chiefly of the sesquiterpene humulene, together with various oxygenated bodies, to which the oil owes its peculiar odour. Other constituents are α- and β-lupamaric acids, choline, resin, and wax (see Lupulus).
Action and Uses.—Lupulin is an aromatic bitter, and is reputed to be mildly sedative. It is occasionally administered as a hypnotic, either in pills, with alcohol as an excipient, or enclosed in a cachet. Preparations of lupulin are not much used in this country.
Dose.—1 to 3 decigrams (2 to 5 grains), or more.
- Fluidextractum Lupulini, U.S.P.—FLUIDEXTRACT OF LUPULIN.
- Lupulin, 100; alcohol (95 per cent.), sufficient to produce 100. Average dose.—5 decimils (0.5 milliliters) (8 minims).
- Oleoresina Lupulini, U.S.P. and B.P.C.—OLEORESIN OF LUPULIN.
- A thick liquid which will barely pour. It should be preserved in a well-stoppered bottle. It has the properties of lupulin. Dose.—1 to 3 decigrams (2 to 5 grains).
The British Pharmaceutical Codex, 1911, was published by direction of the Council of the Pharmaceutical Society of Great Britain.