Astringents: Zinc Sulphate, Potash Alum : Pharmaguideline -->

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Astringents: Zinc Sulphate, Potash Alum

As well as shrinking and drying the tissues, the effects of an astringent are tissue contraction and shrinkage.


As well as shrinking and drying the tissues, the effects of an astringent are tissue contraction and shrinkage. Astringents can be categorized into the following groups based on how they act:
  • Epinephrine and cocaine are two drugs that narrow the small blood vessels and decrease blood supply.
  • Alcohol and glycerol abstract water from the tissues.
  • Those substances cause the superficial tissue layers to coagulate, such as calamine or alum (e.g., metallic astringents).
As well as reducing swelling of mucous membranes resulting from inflammation and infection in the nose, digestive tract, and urinary tract, astringents are frequently used as styptics to stop bleeding and drying up excess secretions.

In other words, Astringents are drugs and lotions that cause body tissues to contract, control blood flow, or prevent fluids from flowing. Astringents have the effect of contracting tissues. Bleeding can be treated with an astringent by stopping the flow of blood.


  • Only affect the superficial layers of the skin.
  • Reduce the permeability of the cell membrane.
  • Have a local antiseptic and styptic effect.
  • Protect the skin from external irritations.
  • Stop bleeding by constricting the blood vessels.
  • Mechanically strengthen the surface to reduce exudation.
  • Pain receptor function may be affected. There is a slight pain relief effect.


  • Metallic astringents
  • Vegetative astringents

Zinc sulfate

Treatment or prevention of low zinc levels with the aid of this medication is based on low zinc levels alone or with oral rehydration therapy. Topical astringents are also possible with this medication. Sodium sulfate injection, USP is intended for use in conjunction with intravenous solutions for transplantation. To aid in the healing of skin wounds and ulcers, astringents with zinc sulfate as active agents are applied topically. A variety of eye drops also contain this ingredient to treat minor allergic conjunctivitis. It can act as an emetic when taken orally but is not recommended for this use due to toxic side effects. For nutritional zinc deficiency, it is used in smaller dosages with sustained release. Zinc deficiency is treated more successfully with soluble formulations, as they cause fewer gastrointestinal disturbances. RNA and DNA polymerases, alkaline phosphatases, and lactic dehydrogenases are some of the enzymes that require zinc. Zinc assists in wound healing promotes normal growth rates, maintains normal skin hydration, and stimulates the sense of smell and taste.

Zinc absorption - Zinc from the diet is absorbed about 20 to 30%, mainly from the duodenum and ileum. Food bioavailability determines how much zinc is absorbed. Zinc's bioavailability is best found in red meat and oysters. At an alkaline pH, phytates may interfere with zinc absorption by chelating and forming insoluble complexes. Afterward, zinc is bound to the protein metallothionein in the intestine. The ileum and colon can restore zinc's entero-pancreatic circulation if endogenous zinc is reabsorbed.

Potash alum

Alum consists of the chemical formula KAI(SO4)2.12H2O. Along with this, the boiling point is said to be 200° C whereas the melting point is 92-95° C.

Mucous membranes that have swollen due to inflammation of the nasal, digestive, or urinary passages, or that have excessive secretions are reduced by potassium alum. In addition to stopping bleeding, the coagulation cascade is induced. In drugs, potassium alum has mainly astringent, antiseptic, and adjuvant properties. Astringent action occurs as a result of the induction of coagulation within the superficial tissues until a crust is formed. Upon the formation of alum ions, the plasma proteins are neutralized, causing coagulation.

Absorption - It produces a very large molecule when potassium alum is dodecahydrate. When this substance is used as an astringent in topical OTC, the large molecule cannot be absorbed by the skin. Aluminum salts are readily soluble in the stomach, generating aluminum hydroxide or poor absorption of basic aluminum salts as a result of their consumption.

Properties of potash alum

Crystals of potassium alum have an octahedral structure. Water readily dissolves potassium alum crystals. The material becomes red when heated at a certain temperature and forms a porous, cold substance called 'burnt alum. It consists of alumina and potash sulfate. When exposed to very high temperatures, hot water molecules evaporate, releasing sulfuric acid. Crystallization water made of potassium aluminum sulfate melts at 92°C. The blue litmus changes color when exposed to it because it is acidic.
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Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of, a widely-read pharmaceutical blog since 2008. Sign-up for the free email updates for your daily dose of pharmaceutical tips.
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