Topical agents such as talc, zinc oxide, calamine, zinc stearate, titanium dioxide, and silicone polymers are applied directly to the skin or mucous membranes to protect them from irritation, injury, or inflammation. Talc, zinc oxide, calamine, and zinc stearate are commonly used in dusting powders, ointments, and lotions as mild antiseptics and astringents to soothe skin conditions. Titanium dioxide and silicone polymers are also used as protective topical agents and in products as lubricants, sunscreens, or to prevent bedsores. These protective agents are finely powdered or viscous liquids that are generally inert, odorless, and tasteless when applied

1. TOPICAL AGENTS
PROTECTIVES
G.REVATHI, M.PHARM.,
ASSISTANT PROFESSOR
DEPARTMENT OF PHARMACEUTICAL CHEMISTRY

2. TOPICAL AGENTS
• Topical → pertaining to a particular locality or
place or simply a local application
• Substances are applied directly on the skin or
mucous membrane or any other surface.

3. PROTECTIVES
• Substances are applied over the skin for
protecting it from irritation, injury, inflammation
etc.,
• Used in the form of dusting powder

4. PROTECTIVE AGENTS
1. TALC
2. ZINC OXIDE
3. CALAMINE
4. ZINC STEARATE
5. TITANIUM DIOXIDE
6. SILICONE POLYMERS

5. TALC I.P
Synonym → French Talc, Purified talc
➢Molecular Formula: Mg6 (Si2O5)4 (OH)4
➢Standard : It should contain about 31% of MgO and 63.5% of SiO2
➢Description : It is a purified natural hydrated magnesium silicate,and may contain
small amounts of aluminum silicate.
• Properties
• Very fine, white or grayish white powder.
• It is smooth to touch.
• Odourless and tasteless.
• Its solution is neutral to litmus.
• Practically insoluble in water, dilute acids and alkalies.

6. ➢ Preparation
Native talc is finely powdered and boiled with dilute HCl (to remove impurities like
iron, Cao, iron etc.)
insoluble talc allowed to settle down
Supernatant liquid is removed
washed with water until it becomes free from acid.
Residue is then dried at 1000C

7. • Test for Purity:
✓ Acidity or alkalinity
✓ water soluble substances
✓ Iron
✓ Carbonates
✓ LOD
✓ Chloride

8. ➢ Storage
It should be stored in well closed container.
➢ Medicinal and Pharmaceutical Uses:
1. As a base for dusting powders.
2. As a lubricant for tablet making.
3. As a filtering and distributing agent.
4. Main ingredient for talcum and dusting powder.

9. 2. ZINC OXIDE
➢ Molecular Formula: ZnO
➢ Molecular weight: 81.34gm
➢ Synonym: Zincite
➢ Standard : It should contain Not less than 99% of ZnO
➢ Description : It occurs as mineral zincite
➢ Test for Purity:
• Arsenic
• Lead
• Zinc
• Sulphate
• Carbonate

10. ➢Preparation :
1. Large Scale: Heating metallic zinc, in a current of air to a high temperature. The
metal vapour burns to form the oxide, collected as a fine white powder.
2 Zn + O2 ⎯⎯→ 2 ZnO
2. Medicinal Grade : Zinc oxide is obtained by adding zinc sulphate to a boiling
solution of sodium carbonate. The precipitated zinc carbonate is washed until it
becomes free from sulphate. Now it is dried and ignited, loses CO2 and water, giving
the oxide.
ZnSO4 + Na2 CO3 → ZnCO3 + Na2SO4
ZnCO3 ⎯⎯→ ZnO + Co2

11. How to prepare to ZnO

12. Properties (Physical & Chemical)
1. White or faintly white very fine powder.
2. It is odourless and tasteless.
3. It is insoluble in water and alcohol.
4. It slowly absorbs CO2 from the air and forms basic zinc
carbonate.
5. It reacts with acids forming zinc salts.
ZnO + 2 NaOH → ZnCl2 + H2O
6. It reacts with base forms zincates.
ZnO + 2NaOH → Na2 ZnO2 + H2O

13. ➢Assay :
Back Titration Method
➢Storage
It should be stored in well closed container.
➢Medicinal and Pharmaceutical Uses :
1. as a mild antiseptic and an astringent.
2. for making dental cement.
3. used in various skin diseases.
4. manufacture of adhesive tapes and bandages.

14. 3. CALAMINE
➢Molecular formula:
ZnCO3,Fe2O3 or ZnO, Fe2O3
➢Synonym: Kaolinite
➢Description: Zinc oxide with a
small proportion of Ferric
oxide
➢Standard: contains NLT 98.0
% of ZnO

15. ➢Preparation
▪ Calamine is obtained by calcination( powdered by heating) of
the natural native zinc carbonate.
▪ prepared by mixing zinc oxide with ferric oxide
▪Sieved & fine powder is collected.

17. ➢ Properties
1. It is pink powder.
2. Almost odourless and tasteless.
3. Almost insoluble in water but dissolved completely in mineral acids.
➢ Assay
Acidimetry – alkalimetry titration
➢Storage condition:
It should be stored in well closed container.

18. TEST FOR IDENTITY
• Calamine + Boiled with HcL
• → filtered
→drops of ammonium thiocyanate is added to filtrate
• → Reddish colour is produced.

19. ➢ Test for Purity:
Barium
Calcium
Lead
Chloride
➢ Medicinal USES:
1. Topical protective
2. it is used in dusting powders, ointments and lotions (Calamine
Lotion) is applied on the skin for its soothing, adsorbent and
protective properties.
3. It has better cosmetic acceptability than zinc oxide.

20. 4. Various dermatological conditions including the exudation of
fluids respond reasonably well to calamine.
5. Mild astringent, antiseptic & protective for skin.
6. Phenolated calamine lotion contain 1% liquefied phenol which
provides local anesthetic antiseptic & antipruritic.

21. 4. ZINC STEARATE
➢ Molecular formula: (C17H35COO)2Zn
➢ Molecular weight: 632 gm
➢ Description: Is a compound of zinc with a mixture
of solid organic acids obtained from fat and
consists of zinc stearate and zinc palmitate with
excess of ZnO
➢ Standard: contains 10-12% of Zn

22. ➢Preparation:
Stearic acid is added slowly with constant stirring
To a hot solution of sodium carbonate
Mixture is cooled
And zinc acetate or zinc sulphate is added to sodium stearate formed
Zinc stearate is precipitated
Collected, washed and dried

23. Na2CO3 + 2C17H35COOH = 2C17H35COONa + H2O + CO2
2C17H35COONa + ZnSO4 = (C17H35COO)2Zn + Na2SO4
➢Physical Properties:
✓White bulky, fine powder
✓Characteristic odour
✓unctuous to touch and readily sticks to skin
✓Practicallly insoluble in water
➢Preparation:

24. ➢Chemical properties:
✓ When heated at high temperature → it fuses and give fumes which are
inflammable and smell of burning fat
✓ Residue of ZnO is left behind
✓ It is decomposed by hot mineral acids with liberation of stearic and
palmitic acids.
(C17H35COO)2Zn + 2HCl = 2 C17H35COOH + ZnCl2
Stearic acid

25. ➢Test for Purity:
✓Arsenic
✓Chloride
✓Heavy metals
✓Sulphate
✓Acidity or alkalimetry
➢Assay :
Complexometric titration
➢Storage :
Store in a well-closed container

26. ➢Medicinal and Pharmaceutical uses :
✓Used as a Dusting powder
✓Acts as a mild antiseptic and astringent
✓Used in the form of ointment in several skin conditions as soothing and
protective agent
✓Added as a lubricant in tablet making
✓Used as a solid diluent

27. 5.TITANIUM DIOXIDE
➢Molecular formula: TiO2
➢Molecular weight: 79.60 gm
➢Synonym: titania
➢Description: It is an oxide of Titanium (Ti )
➢Standard: contains not less than 98 % of TiO2

28. ➢Preparation
Titanium dioxide is prepared by heating ilmenite FeTiO3 with hydrogen chloride and chlorine.
2FeTiO3 + 4HCl + Cl2 = 2FeCl3 + 2TiO2 + 2H2O
➢Physical Properties
1. White powder, odourless and tasteless.
2. Insoluble in water and in dilute mineral acids.
3. It dissolves slowly in hot H2SO4 and ammonium sulphate forms double salt.

29. ➢Chemical properties:
TiO2 in dil. Sulphuric acid reacts with hydrogen peroxide → gives orange
red colour due to formation of titanium peroxide and is used for test for
identity for TiO2.
➢ Test for Purity:
✓Arsenic
✓Barium
✓Heavy metals
✓Iron
✓Acidity or alkalinity

30. ➢Assay :
By Complexometric Method
➢Storage :
It is stored in well closed container.
➢Use:
1. Very good topical protective.
2. Used as a white pigment in paints
3. Because of high refractive index it is used in sun-tan preparations.

31. 6. SILICONE POLYMERS
• They are polymers having the general formula
✓ Compounds that are formed as a result of the bonding of silicon, oxygen and carbon by condensation are
known as silicones.
✓ One of the building blocks of silicones is dimethyldihydroxysilane (CH3)2Si(OH)2
✓ Two dimethyldihydroxysilane molecules undergoes condensation with elimination of a molecule of
water

32. Repeated condensation → formation of macro molecules or polymers.
These are known as Silicones.
Si-O-Si linkage in these molecules is very strong
General formula of silicones → [(CH3)2SiO-)]n
Si
CH3
C
H3
O
H
Si
CH3
O O
Si
O Si
CH3
O
Si
C
H3
CH3
O CH3
CH3
C
H3
CH3
C
H3

33. ➢Properties:
1. Highly viscous liquids.
2. Viscosity increases with increase in molecular weight.
3. They are stable towards heat and chemical reagents.
4. They can be used as lubricants over a wide range of temperature.
5. Stable even at very high and very low temperatures and are water repellant.
➢Uses:
It is used for making water-proof cloth and lubricants which donot freeze even at low temperatures.

34. ACTIVATED DIMETHICONE
➢Molecular formula: (CH3)2Si-[OSi(CH3)2]-CH3
➢Molecular weight: 237 gm
➢Synonym: Simethicone
➢Description: It is an Activated polydimethylsiloxane
➢Standard: contains not less than 90 % of polydimethylsiloxane and not more than 7% of SiO2

35. ➢Preparation
Is prepared by hydrolysis and polycondensation of dichlorodimethylsilane (CH3)2SiCl2
and chloro trimethylsilane (CH3)3SiCl.
➢Properties
1. Grey, translucent viscous liquid.
2. Odourless and tasteless
3. Insoluble in water and methyl alcohol
4. Soluble in Organic solvents such as CCl4, Chloroform and ether

36. DIMETHICONE PREPARATON…..

37. ➢Official test for identity:
sample treated with CCl4 and dil.HCl
Shaken well for 5 minutes
lower layer is shaken with anhydrous sodium sulphate to remove any water
Mixture is centrifuges till the clear supernatant liquid is obtained
IR absorption spectrum of resulting solution → exhibits maxima at same
wavelength as in spectrum of R.S (PDMS)

38. ➢Test for purity:
✓Acidity
✓Heavy metals
✓Defoaming activity
➢Storage:
Stored in a tightly closed container

39. ➢Medicinal and Pharmaceutical uses:
1. Protective and Defoaming agent
2. Antacid mixtures in the treatment of flatulence
3. Are used a Water repellant and have low surface tension
4. Used in barrier creams for protecting skin against water soluble irritants
5. Creams, lotions, ointments containing silicone polymers employed for
prevention of bedsores and napkin rash and to protect the skin against
trauma due to colostomy discharge
6. Also used in lubricants for hypodermic syringes