Dental Pharmacology Lecture Slides on Astringents by Sanjaya Mani Dixit Assistant Professor of Pharmacology at Kathmandu Medical College

1. Astringents
Sanjaya Mani Dixit
Assistant Prof of Pharmacology

2. Astringents
The word "astringent" derives from Latin adstringere,
meaning "to bind fast".
Definition: Astringent is a drug that reacts chemically with
cellular proteins producing limited coagulation which is
accompanied by shrinkage of body tissues.
Astringent protects from external irritation and reduces
cellular permeability
It also possesses local styptic and local antiseptic actions
Examples:
 very cold water,
 rubbing alcohol and zinc oxide, and
 vegetable substances such as tannic acid

3. Astringents
Astringent medicines cause shrinkage of mucous membranes
or exposed tissues and are often used internally to check
discharge of blood serum or mucous secretions
 sore throat,
 hemorrhages,
 diarrhoea, or
 peptic ulcers.
 Externally applied astringents, cause mild coagulation of
skin proteins, dry, harden, and protect the skin
 Acne sufferers are often advised to use astringents if they
have oily skin

4. Uses of astringents
• Stop bleeding
• Clean the face and prevent Acne Breakouts
• Haemorrhoids
• Relieve the discomfort and itching caused by
• insect bites,
• minor abrasions and
• Athlete’s foot

5. Astringents
• Astringents are substances that precipitate proteins, but do
not penetrate cells and this affect the superficial layer of
mucosa only.
• Aluminum chloride and ferrous sulfate are preferred
astringents in dentistry since they cause minimum tissue
damage.
• Examples
– Alum
– Aluminium chloride
– Zinc chloride (8-20%)
– Tannic acid

6. Characteristics
Affect only the superficial layer.
Reduce cellular permeability.
Make the surface mechanically stronger, decrease exudation.
Protect from external irritation.
Possess local styptic and local antiseptic action.
May interfere with the function of pain receptors.
The pain relieving action is mild.

7. Astringents- Types
1. Vegetable astringents
Tannic acid, Gallic acid
2. Metallic astringents –
Aluminium salts – alum, aluminium chloride, aluminium
acetate
Zinc salts – zinc chloride, zinc sulfate
Ferric chloride
Strontium chloride
Silver nitrate and
Copper sulfate
3. Others – very cold water, alcohol

8. Classification based on MoA
1. Those that decrease the blood supply by narrowing
the small blood vessels, e.g. epinephrine, cocaine.
2. Those that abstract water from the tissue, e.g.
glycerol and alcohol.
3. Those that coagulate the superficial tissue layers into
a crust, e.g. metallic astringents such as calamine or
alum.

9. Action of Astringents
The general condensation of tissue.
Diminished caliber of the arteries, veins, capillaries, absorbents,
and ducts.
Diminished secretion, exhalation and absorption.
Constipation of the bowels; and increased firmness along with
contraction of the pulse.
Constrict blood vessels to stop bleeding.
Harden the epidermis creating a barrier against infection.
Increase in appetite and invigorate digestion.
Antioxidant.
Inhibit mutagenicity of carcinogens.

10. Indications
• To check morbid discharges – generally or locally
• To obviate morbid relaxation – generally or locally
• To check inflammation in its earliest stage – applied directly at
the site
• Swollen, inflamed and/or leaky tissues : -diarrhea, dysentery -
IBS, IBD -leukorrhea (thick whitish/yellowish vaginal
discharge)
• Catarrhal states -cough, bronchitis, sore throats -Canker sores
and other oral infections -Varicose veins
• Minor bleeding: -Menorrhagia (heavy flow) -Hemorrhoids -
Small wounds and burns

11. Clinical Uses
• Used internally to check discharge of blood,
serum or mucous secretions (in sore throat,
diarrhea, hemorrhage or peptic ulcers).
• Externally applied astringents, which cause
mild coagulation of skin proteins, dry, harden,
and protect the skin.
• Cleaning the face and preventing acne
breakouts.
• Stoppage of bleeding.

12. Astringents used in Dentistry
• Tannic acid and tannins
• Vegetable astringent.
• Source – nutgalls (tannic acid), tea, catechu,
betelnut (tannins).
• Actions : strengthen gums and check bleeding.
tannins bind salivary proteins, precipitate
them, causing dry sensation

13. Astringents used in Dentistry
• Their preparations are used as astringent mouth
wash, astringent dentrifices, local haemostatics,
mummifying agent and obtundant.
• Efficacy is dubious.

14. Zinc chloride - caustic astringent
• Actions : -Zinc reduces the permeability of cell
membrane, alters the capillary epithelium, inhibits
transcapillary movement of plasma proteins and
reduces local edema, inflammation, exudation and
mucus secretion.
• Ulcerative gingivitis, pyorrhoeal pockets and apthous
ulcers.
• Included in several mouthwashes and dental gels.

15. Zinc sulfate
 topical astringent for mucous membranes.
 indications :
 mastoiditis,
 stomatitis and
 chronic alveolar abscess.
 Included in mouthwashes and lotions.

16. Copper sulfate
Used as an astringent in indolent ulcer of gums.
Also used as a fungicide.
Disadvantage – stain the teeth. Alum
Has astringent, antiseptic and haemostatic
properties.
Indications : To harden the gums or for
inflamed/ulcerated gums.
Example- styptic pencils used to prevent bleeding
from shaving cuts.

17. Alum as Astringent
• Aluminium chloride, ferric chloride, strontium
chloride
• Included in many mouthwashes and gels.
• Provide symptomatic relief, heal lesions, reduce
dentinal sensitivity and bleeding of gums. Oak’s bark
• actions : tighten tissues and strengthen blood
vessels.
• indications : weak and bleeding gums, damaged
gums

18. Alum as Astringent
Hydrolysable tannins are not recommended for long-term
use.
Prolonged use can reduce absorption of nutrients, and cause
or worsen constipation.
Form complex with metal ions and reduce absorption.
Irritation of mucous membranes.
Carcinogenic when injected subcutaneously.

19. That’s All
ENJOY
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