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For what purposes are they used?

They are used to check profuse secretion (e. g., ptyalism, etc.) or morbid discharges (e. g., diarrhoea), to overcome relaxation of the tissues, and as hæmostatics and styptics.

How may the astringents be classified?

They are divided into vegetable and mineral astringents.

VEGETABLE ASTRINGENTS.

What are the vegetable astringents?

They are tannic and gallic acids, and the various plants which are used as astringents on account of containing these principles.

Name the vegetable astringents.

Tannic acid, gallic acid, nutgalls, catechu, kino, krameria, hæmatoxylon, white-oak, geranium, witch-hazel, red and white rose, sumach, chestnut leaves.

ACIDUM TANNICUM-TANNIC ACID.

What is tannic acid?

Tannic acid (gallo-tannic acid-digallic acid) is an organic acid obtained from nutgall. It is widely distributed throughout the vegetable kingdom and exists under two forms, gallo-tannic acid (which is the official variety and strikes a blue-black color with the ferric salts) and kino-tannic acid (which produces a greenish-black color with the same salts). Gallo-tannic acid is a light yellowish, amorphous powder, usually cohering in the form of glistening scales or spongy masses, without smell, but having a strongly astringent

taste.

It is freely soluble in water and in alcohol, and may readily be dissolved in glycerin by the aid of moderate heat.

What are its physiological effects?

Tannic acid is a powerful astringent, coagulating albumins, contracting blood-vessels and constringing tissues with which it comes in contact. It checks the secretions of the alimentary canal when taken internally, and restrains peristalsis, thus tending to constipate. It is converted into an alkaline tannate and into gallic acid in the prima via and slowly absorbed. It is eliminated by the fæces and urine under its own form and as gallic and pyrogallic acids.

For what purposes is it used in medicine?

When remote astringent effects are desired gallic acid is preferable, but tannic acid is employed whenever the part to be acted on is so situated that the drug can come in direct contact with it. Thus, it is given to arrest morbid discharges from the bowels in diarrhoea and dysentery, both internally and by enema, and is used externally for the same purpose in leucorrhoea, gleet, colliquative sweating, and as an application to chronic ulcers. To counteract relaxation of tissues it is employed in the treatment of spongy gums, chronic pharyngitis and laryngitis, mercurial stomatitis and hemorrhoids. It is used also to arrest hemorrhages from the nose, gums, pharynx, stomach and bowels, and locally as a styptic; to harden tissues subjected to pressure, as in threatened bed-sores and tender feet, and as an antidote to antimony and other metallic poisons.

Dose, in diarrhoea, gr. j-xv (0.06-1.0) in pill; in hemorrhage, gr. v-xx (0.3-1.3) in powder. The troches (trochisci acidi tannici) each contain gr. j (0.06), and may be used in relaxed palate or sore throat. The ointment (unguentum acidi tannica) or the glycerite (glyceritum acidi tannici), a solution in glycerin, may be used locally.

ACIDUM GALLICUM-GALLIC ACID.

What is gallic acid?

Gallic acid is an organic acid, usually prepared from tannic acid, and is tannic acid + a molecule of water; thus, HC,H,O, (tannic acid) + 3H2O=2(HC,Н¿O¿+ H2O) (gallic acid). It occurs as white or pale fawn-colored, silky, interlaced needles or triclinic prisms; odorless, having an astringent or slightly acidulous taste. It is very soluble in boiling alcohol and boiling water, less so in cold alcohol, glycerin, ether, or cold water. It does not coagulate albumin, and hence is not as efficacious as a local astringent, but is preferred to tannic acid when it is desirable that the astringent should be absorbed and act through the blood on some remote part. It is used as a hemostatic in hemoptysis, hematuria, and uterine hemorrhage. It is also employed to lessen secretion, as in colliquative sweats and bronchorrhoea, and to check morbid discharges, as in chronic albuminuria. Dose gr. v-xxx (0.3-2.0), in powder, pill, or solution.

Describe the preparations, doses, and uses of the vegetable astringents which owe their virtues to tannic and gallic acids.

GALLA (nutgall) is an excrescence found on Quercus lusitanica, the gall oak (Nat. Ord. Cupuliferæ) caused by the punctures and deposited ova of a fly (Cynips Quercûs folii or Diplolepis Gallæ tinctoriæ). Before the maturity of the larvæ and their escape from the gall, they contain tannic acid (50-60 per cent.) and gallic acid (3 per cent.); afterward they are much inferior and contain comparatively little of these substances.

They are but little used except as the source of tannic and gallic acids. The tincture (tinctura galla) is chiefly used as a chemical test. The ointment (unguentum galla) combined with powdered opium is sometimes applied to hemorrhoids.

CATECHU, an extract prepared from the wood of Acacia Catechu (Nat. Ord. Leguminosa), contains kino-tannic and catechuic acids (catechin). It is a powerful astringent, much used in diarrhæas and to some extent in hemorrhages, and locally as an astringent in sore throat, as an injection in gonorrhoea and leucorrhoea, and as a styptic. Dose gr. x-xxx (0.6–2.0) in emulsion or capsules. Of the compound tincture (tinctura catechu composita) f3j-iij (4.0-12.0) may be given. The troches (trochisci catechu) each contain gr. j (0.06).

KINO, the inspissated juice of Pterocarpus Marsupium (Nat. Ord. Leguminosæ) and other trees; contains kino-tannic acid, kinoïn, pyrocatechin, etc., and has similar properties and uses to catechu. Dose of the powder gr. x-xxx (0.6-2.0); of the tincture (tinctura kino) f3j-ij (4.0-8.0).

KRAMERIA, the root of K. triandra and of K. Ixina (Nat. Ord. Polygalea), S. American shrubs; contains kramero-tannic acid, and is a powerful astringent, similar to kino and catechu. Dose of the extract (extractum krameria) gr. v-xv (0.3–1.0); of the fluid extract (extractum krameric fluidum) f3ss-j (2.0-4.0); of the tincture (tinctura krameria) f3ss-ij (2.0-8.0); of the syrup (syrupus krameria) f3j-jv (4.0-15.0). The troches (trochisci krameria) each contain gr. j (0.06).

HÆMATOXYLON, logwood or Campeachy wood, is the heart wood of H. campeachianum (Nat. Ord. Leguminosa), containing annic acid, hematoxylin, etc. It is a good astringent in diarrhoeas due to relaxation, especially in children, but the discharges will stain the linen blood-red. Of the extract (extractum hæmatoxyli) the dose is gr. x-xxx (0.6-2.0).

QUERCUS ALBA, or white oak (Nat. Ord. Cupulifera). The bark is official, and contains querci-tannic acid. It is occasionally used in diarrhoeas, but more often as an enema in hemorrhoids and prolapsus ani, or as a vaginal wash in leucorrhoea or relaxed conditions with tendency to cystocele or rectocele. It makes an indelible stain on linen.

GERANIUM, the rhizome of G. maculatum, crow's foot or crane's bill (Nat. Ord. Geraniacea); contains tannic and gallic acids, and is an efficient indigenous astringent. Dose of the fluid extract (extractum gerani fluidum) f 3ss-j (2.0-4.0).

HAMAMELIS, the leaves of H. virginica or witch hazel (Nat. Ord. Hamamelacea); contains tannic acid and a bitter principle. It is an astringent and seems to contract the veins of the skin and mucous membranes. It has been used in passive hemorrhages as a hemostatic, as an astringent enema in hemorrhoids, and locally in congestions and inflammations. Dose of the fluid extract (extractum hamamelidis fluidum) f3ss-j (2.0-4.0).

ROSA GALLICA (red rose); ROSA CENTIFOLIA (pale rose), (Nat. Ord. Rosacea). Their petals are official. The former is a very

mild astringent, but they are principally used as flavoring ingredients and vehicles. The preparations of red rose are a fluid extract (extractum rosa fluidum), a honey (mel rosœ), a syrup (syrupus rosœ) and a confection (confectio rosa); those of pale rose are a triple or stronger rose water (aquæ rosa fortior), and another milder water (aquæ rosae) from which is made an ointment (unguentum aquæ rose-cold cream).

RHUS GLABRA (sumach) (Nat. Ord. Anacardiex). The fruit

is official. It is a good astringent in sore mouth and pharyngitis. The fluid extract (extractum rhoïs glabræ fluidum) may be diluted with two or more parts of water and used as a gargle.

CASTANEA, the leaves of C. dentata or chestnut (Nat. Ord. Cupuliferæ), is astringent and supposed to possess antispasmodic properties. It is chiefly used in whooping-cough. Dose of the fluid extract (extractum castanea fluidum) f3ss-ij (2.0-8.0).

MINERAL ASTRINGENTS.

Name the mineral astringents.

Most of the metallic salts possess astringent properties, but those especially used for this purpose are the lead salts; alum ; aluminium sulphate; the salts of copper, of zinc, of silver, and of bismuth; and cerium oxalate.

PLUMBUM-LEAD.

What is the source of lead?

Lead is obtained by roasting galena, the native sulphide.

What are its physiological actions?

Metallic lead is inert, as are probably also the sulphide and sulphate. All other salts of lead, when applied locally in solution, are astringent, or if the solution be strong, irritant. In medicinal doses they are astringent to the alimentary canal, decreasing its secretions and also the secretion of bile. They are but slowly absorbed. When taken for some time they reduce the volume and frequency of the pulse by stimulation of the cardio-inhibitory centre and the peripheral filaments of the vagi. They are eliminated by the liver and kidneys.

What are its toxicological actions?

In large doses several of the lead salts are capable of causing acute poisoning, the symptoms being intense gastro-intestinal irritation, vomiting, coma, paralysis and collapse.

Chronic poisoning is caused by saturation of the system with lead, either by drinking pure water conveyed in lead pipes (the contained air forming a soluble oxide), constantly eating substances adulterated with lead salts, exposure in lead factories, etc. Lead colic (or

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