收敛药

作用机制与药理效应

The primary reaction when using astringents is partial denaturation (coagulation) of proteins in the mucus or exudate on the wound surface. The coagulated proteins form a dense film that isolates the underlying tissues.

Due to this isolation, the following pharmacological effects develop:

• Analgesic: a direct consequence of protecting nerve endings from external irritants.
• Anti-inflammatory: the drugs cause local vasoconstriction, reduce vascular wall permeability, decrease exudate release, and generally suppress the inflammatory response.

The drugs are usually well tolerated, but the effect is short-lived and reversible. In rare cases (especially with prolonged use of metal-containing agents or individual intolerance), nausea, vomiting, and dyspepsia are possible.

Classification of astringents

Drugs are classified into two main groups based on their origin.

1. Organic (plant-derived) They act more mildly and are used predominantly in the form of decoctions, infusions, and enemas. These include preparations containing tannin. Sources include:

• Herbs: St. John's wort.
• Leaves: sage.
• Flowers: chamomile.
• Rhizomes: bistort, burnet, cinquefoil.
• Berries: blueberry, bird cherry.
• Bark: oak.

2. Inorganic (weak solutions of metal salts) This group includes bismuth subnitrate, dermatol (bismuth subgallate), xerform (bismuth tribromophenate basic), lead acetate, alums, as well as zinc and copper sulfates. An important feature of metal salts is their antiseptic (antimicrobial) action, which is achieved through the coagulation of proteins of the microbial cell itself.

Concentration-dependent effect: in low doses, inorganic salts act as astringents, while in high doses, they exhibit a caustic effect (silver, aluminum, zinc, copper salts). This property is used to remove excess granulations and stop bleeding in superficial cuts.

临床应用

Astringents are prescribed topically and internally (enterally) for various pathologies:

• Gastrointestinal diseases: for acute inflammation, gastritis, enteritis, and colitis, plant-based remedies are used (in case of infectious origin, along with antibiotics). For peptic ulcer disease, chronic gastritis, and duodenitis, both plant-based preparations and bismuth subnitrate (a component of the combination drugs Vikair and Vikalin) are used.
• Dentistry and ENT practice: for acute and chronic gingivitis, stomatitis, and pharyngitis, plant-based remedies for gargling are preferred.
• Dermatology and surgery: bismuth preparations in the form of ointments and powders are used to treat burns, ulcers, eczema, and dermatitis. Lotions with lead acetate and alums are applied to wounds.
• Ophthalmology and urology: irrigations and eye drops with zinc sulfate are used for urethritis, vaginitis, and conjunctivitis.

Characteristics of tannin

By chemical nature, tannin is gallotannic acid. It is obtained from nutgalls (Gallae turcicae — growths on the shoots of the Little Asian oak) and certain plants of the sumac family.

Application of tannin:

1. Topical: 1–2% solutions for rinsing the oral cavity and throat, 3–10% solutions and ointments for burns and ulcers.
2. Enteral (for diarrhea): pure tannin is not prescribed internally due to severe gastric irritation. Its protein compounds are used instead (Tanalbin, Tealbin preparations), which do not precipitate on the gastric mucosa, ensuring action directly in the intestine.
3. Toxicological: tannin is an important antidote. A 0.5% aqueous solution is used for gastric lavage in oral poisonings with heavy metal salts and alkaloids (morphine, cocaine, atropine, nicotine). It binds toxins, preventing their absorption.

课堂与考试常见问题

该主题的其他拓展内容

• Mechanisms of caustic and antiseptic action of inorganic salts
• Pharmacological properties of bismuth preparations and their place in the treatment of peptic ulcer disease
• Specifics of using astringents in dental practice
• Physicochemical features of the interaction of tannin with alkaloids
• Principles of combining organic astringents with antibiotics

“镇痛药”板块的其他主题

本资料由 WhiteCoat Pro 讲师根据医学院校教学大纲编写。仅供教育参考。