Astringent

It may provide some more valueable information about inorganic drugs used as astringents for the pharma students in various aspects

1. Ms. Revathi Gnanavelou., M.Pharm.,
Assistant Professor,
Department of Pharmaceutical chemistry,
SVCP
ASTRINGENT

2. INTRODUCTION
AstringentArethesubstanceswhichprecipitatestheprotein.
Isadrugwhichmakesthecellshrinkbyprecipitatingtheproteinsfromtheirsurfaces.
Usedinlotionstohardenandprotecttheskinandtoreducebleedingfromminorabrasions
Otherpreparations,inwhichtheyareusedareanti-perspirantpreparation,mouthwashes,eye
drops,throatlozengesetc.,
Itstimulatesgrowthofnewtissues,whentheyappliedtopicallyandproducescorrosiveeffectin
concentratedsolutionstoremoveundesireabletissuegrowtheg:Warts.

3. Examples
* Alum
* Zinc Sulphate

4. 1. SYNONYM: Potash Alum, Aluminiumpotassium sulphate
2. MOLECULAR FORMULA: KAl(SO
4)
2, 12H
2O
* Alum is potassium aluminiumsulphate.
* It is a double salt containing potassium and
aluminiumsulphatewith 12 molecules of water of hydration.
3. MOLECULAR WEIGHT: 474 gm
4. STANDARD: Contains 99-100.5% of Alum
1. ALUM

5. 5. PREPARATION:
It is prepared by adding a hot concentrated solution of potassium sulphateto a hot solution of
an equal amount of aluminiumsulphateconcentrated, cooled and crystallizes out
K
2SO
4+ Al
2(SO
4)
3+ 24 H
2O →2KAl (SO
4)
2. 12H
2O
6.PHYSICAL PROPERTIES:
1. Colourlesstransparent crystals having a sweet astringent taste.
2. It is soluble in water but insoluble in alcohol.
3. At 200
0
C it loses its water at crystallization and becomes anhydrous.
4. Acidic to litmus and pH 4.6

6. 7. CHEMICAL PROPERTIES:
when alum is melts at 90
0
C and heated at 200
0
C losses all water leaving as white
residue known as Burnt Alum containing anhydrous aluminiumand potassium sulphates.
8. OFFICIAL TEST FOR IDENTITY:
Small quantity of solution is treated with water + NaHCO
3 gives Reaction of Potassium
9.Test for Purity:
Arsenic
Heavy metals
Iron
Zinc
Ammonium Salts

7. 10. ASSAY:ComplexometricTitration Method
11. STORAGE:
Stored in a well-closed container
12. MEDICINAL AND PHARMACEUTICAL USES:
1. Antiseptic and local styptic (to stop bleeding from cuts)
2. Precipitates the protein and protects to harden the skin
3. Used in Biological preparations of such as alum precipitated tetanus toxoid and alum
precipitated diphtheria toxoid.

8. 1. MOLECULAR FORMULA: ZnSO
4. 7H
2O
2. MOLECULAR WEIGHT: 288 gm
3. STANDARD: Contains 99% of ZnSO
4. 7H
2O
4. PREPARATION:
Prepared by boiling the slight excess of Metallic zinc with dilute sulphuricacid.
Zn + H
2SO
4ZnSO
4+ H
2
Solution is filtered to remove unreacted zinc , concentrated and crystallized.
2. ZINC SULPHATE

9. 5. PROPERTIES:
Colourless, transparent crystals or crystalline powder
Odourless and astringent or metallic taste
Efflorescent in dry air
Easily soluble in water and insoluble in alcohol and glycerine
6. OFFICIAL TEST FOR IDENTITY:
Gives the characteristic reactions of zinc and of sulphates

10. 7. TEST FOR PURITY:
Arsenic
Purity and colour of solution
pH
Iron
Chloride
8. ASSAY:
Complexometrictitration
9. INCOMPATIBILITY:
Alkali carbonates, hydroxides and astringent decoctions and infusions.

11. 10.STORAGE:
Since,itis efflorescent , store in a well-closed, non-metallic container.
11.PHARMACEUTICAL AND MEDICINAL USES:
Internally used as a Emetic
Externally used as Astringent in lotions and eye drops
Treat conditions associated with zinc deficiency such as acrodermatitisenteropathica.
Used as a ophthalmic ingredient in ophthalmic solution

12. References
1.Inorganic chemistry by
Mohammed Ali
2. Pharmaceutical chemistry by
Rajasekaran
3. Inorganic chemistry by
Paradkar
Contact: [email protected]

13. ASTRINGENT
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