Synonym.—Witch Hazel Bark.
Hamamelis bark is obtained from Hamamelis virginiana, Linn. (N.O. Hamamelideae), a shrub common in the United States and Canada. It is also official in the U.S.P. The bark should be collected in the spring, and dried. It occurs in thin channelled or curved pieces, about 1.5 millimetres thick, and 0.5 to 2 decimetres long, sometimes covered with a smooth (or, in older pieces, scaly) grey cork marked with transverse lenticels. The cork is often removed, and the cortex, which then forms the outer layer, is pale reddish-brown in colour and smooth. On its inner surface the bark is pale reddish-pink, and finely striated longitudinally, with small pieces of white wood occasionally adhering to it. The cork breaks with a short fracture, but the bast is fibrous. Though without odour, the bark has an astringent and slightly bitter taste. It yields on incineration about 5 per cent. of ash.
Constituents.—The bark contains about 6 per cent. of tannin, of which part is crystalline hamamelitannin, and part amorphous. Gallic acid, resin, fat, phytosterol, and other bodies are also present.
Action and Uses.—Hamamelis bark is a local astringent and haemostatic. The tincture is used, diluted with water, as a lotion to small wounds, bruises and inflammatory swellings, and applied externally or injected into the rectum for piles. Tincture of hamamelis, and extract of hamamelis, are given internally, quite irrationally, to check bleeding from the lungs or other organs. It has been pointed out that the tannins which form the active constituent are changed into sodium gallate on reaching the blood. Sodium gallate has no astringent properties, and none of the drugs which owe their action to tannin exert any remote astringent action.
Dose.—1 to 3 grammes (15 to 45 grains).
- Aqua Hamamelidis, U.S.P.—HAMAMELIS WATER.
- Hamamelis bark, 100; water, 200; alcohol (95 per cent.),15. Macerate the bark in the water for twenty-four hours; distil 85, add the alcohol, and mix thoroughly. Average dose.—8 mils (2 fluid drachms).
- Extractum Hamamelidis, B.P.C.—EXTRACT OF HAMAMELIS. Syn.—Extract of Witch Hazel.
- A soft extract prescribed in pills, often with extract of ergot or extract of hydrastis (see also Hamamelinum). Dose.—3 to 12 centigrams (1/2 to 2 grains).
- Gossypium Hamamelidis, B.P.C.—HAMAMELIS WOOL. 1 (tincture) in 4.
- Tinctura Hamamelidis, B.P.—TINCTURE OF HAMAMELIS.
- Hamamelis bark, in No. 20 powder, 10; alcohol (45 per cent.), sufficient to produce 100. Add 5 of the alcohol to the drug, to moisten it, and proceed with the percolation process. Tincture of hamamelis is a useful astringent and styptic, and is applied as an astringent lotion or injection diluted with 10 or 20 parts of water to stop bleeding or check mucous discharges, and for haemorrhoids. It has no action after absorption. Dose.—2 to 4 mils (1/2 to 1 fluid drachm).
- Unguentum Extracti Hamamelidis, B.P.C.—EXTRACT OF HAMAMELIS OINTMENT. 1 in 8.
The British Pharmaceutical Codex, 1911, was published by direction of the Council of the Pharmaceutical Society of Great Britain.