Astringents - it's types , uses , procedure.

Description about astringents.

1. ASTRINGENTS By- Dr. Chitranshi Hyanki Department of Pharmacology & Therapeutics King George’s Medical University

2. Introduction An astringent is a chemical that shrinks or constricts body tissues. The word derives from the Latin ‘adstringere’, which means "to bind fast". Calamine lotion, witch hazel, and yerba mansa, a Californian plant, are astringents. These are the drugs used to harden and protect the skin and to stop bleeding from minor scratches. These drugs cause contraction of cells by precipitating proteins from their surfaces, thereby, protect the skin.

3. Zinc sulphate Zinc sulfate is an inorganic compound. It is used as a dietary supplement to treat zinc deficiency and to prevent the condition in those at high risk. Side effects of excess supplementation may include abdominal pain, vomiting, headache, and tiredness. Formula : ZnSO4.7H20 Molar mass : 287.6 g/mol

4. Density: 3.54 g/cm? Boiling point: 740 °C ChEBI ID : 35176 Classification: Sulfate, Inorganic compound

5.  It is prepared by treating zinc chloride with sodium sulphate. ZnCl2 + NazSO4 = ZnSO4 + 2NaCI It is also prepared by boiling metallic zinc with dilute sulphuric acid Zn + H2S04 = ZnSO4 + H

6. Properties  It occurs as transparent crystals or white crystalline powder , odourless, has metallic or astringent taste. Soluble in water and the aqueous is acidic in nature. It is soluble in alcohol. It forms double salt with potassium and ammonium sulphate ( M2SO4 , ZnSO4 . 6H20 ) in dry air it is efflorescent in nature

7. Assay Dissolve an accurately weighted amount of substance in add ammonia water, add ammonia - ammonia chloride buffer to maintain pH 10, add erichrome black T as an indicator and titrate against 0.05m di-sodium EDTA until the color changes to yellow.

8. Uses It is used as an astringent and reflux emetic ( dose 0.6 to 2.0 gms ) Zinc sulphate astringent, used topically for skin wounds/ulcers to assist healing. Also included in some eye drops for minor allergic conjunctivitis. Orally it is an emetic , but is not used for this purpose due to it’s toxic effects. In smaller, sustained release doses, it is used for nutritional zinc deficiency

9. Zinc is a naturally occurring mineral. Zinc is important for growth and for the development and health of body tissues. Zinc sulfate is used to treat and prevent zinc deficiency.

10. Potash alum  Potash alum is a chemical compound widely used as the potassium sulfate dodecahydrate. It is A double salt that is used commonly in medicine and the water treatment process. Potash alum is also known as potassium alum or potassium aluminium sulfate. Potassium alum, potash alum, or potassium aluminium sulfate is a chemical compound: the double sulfate of potassium and aluminium, with chemical formula KAI(SO4)2. It is commonly encountered as the dodecahydrate, KAI(SO4)2.12H2O

11. Formula : KAI(SO4) 2 .12H 2 Molar mass : 474.39 g/mol Melting point: 92.5 °C Density: 1.76 g/cm 3 Solubility in water: 14.00 g/100 mL (20 °C); 36.80 g/100 mL (50 °C) Solubility in other solvents: Insoluble in acetone

12. It is prepared by mixing hot concentration solution of potassium sulphate with an equivalent quantity of hot solution of aluminium sulphate, after cooling, gives potash alum. Al2(SO4).18H20 + K2S04 = KAI(SO4)2-12H20 + 6H20

13. Properties It occurs as white powder or transparent crystalline mass. It is odourless and has sweet or astringent taste. It is soluble in water insoluble in alcohol. The burnt alum contains anhydrous aluminium and potassium sulphat

14. Assay Principle : The aluminium present in alum is first precipitated as aluminium hydroxide by ammonia, which is then ignited to leave the residue aluminium oxide. The weight of Al203 is calculated. 1 gm of residue is equivalent to 9.307 gms of alum

15. Procedure Dissolve an accurately weighted amount of substance in water, add ammonium chloride, few drops of methyl red sufficient ammonia solution. The reaction mixture is boiled and filtered. The residue is washed with 2.5% solution of ammonium nitrate until the washing is free from chloride. The remaining residue Al203 is dried at 120°C and weighed.

16. Uses Used as an astringent Used as a source of Al3 ion Used in styptic pencils to stop bleeding from small cuts. Used in the preparation of precipitated diphtheria and tetanus toxoids.

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