Topical Agents Manik

Topical Agents
Arranged By- Md. Imran Nur Manik,.B.Pharm.;M.Pharm.;(Thesis) RU Page 1
Prepared By- Shadid Uz Zaman At Tadir,.B.Pharm.;M.Pharm. (Professional) DU
Introduction:
Definition:
The compounds which are applied on body surface and are not absorbed into the
circulatory system are called topical agents.
Even though the pharmacological effects of topical products are evident primarily at the
surface to which they are applied there is no saying that the drug will not penetrate into deeper
tissue or enter the general circulation.
Classification
The compounds used topically can be classified into 3 categories based on their usual
action—
1. Protective agents
2. Antimicrobial agents
3. Astringents
Protectives:
Protectives are substances which may be applied to the skin to protect certain areas from
irritation, usually of mechanical origin.
They are applied to topical areas susceptible to constant irritation or already irritated or
inflamed due to moisture, friction, allergy etc.
Desirable properties of an ideal protective agent:
1. Insolubility: Insolubility is a desirable property of protectives because this limits the
absorption of the compounds.
2. Inertness: Protectives should be chemically inert. Compounds which are chemically
unreactive are necessary in order to prevent interactions between the protective
substance and the tissue. In other words, ideal protectives are biologically inactive.
3. Adsorbent action: Since removing moisture tends to lessen mechanical friction and
irritation, adsorbent action is an important property of protectives.
4. Particle size of the product should be small: Protective and adsorbent action is
maximized with decreasing particle size. Small particles offer a larger surface area,
allowing them to adhere to each other, adhere better to the surface of the skin and adsorb
moisture more efficiently. A fine state of subdivision of the particles also offer a smooth
substance which is soothing to apply and aids in preventing irritation due to rubbing or
friction.
Dosage form of protectives:
i. As dusting powders e.g. talc
ii. As suspensions containing, the insoluble protective substance e.g. Aluminum (Al)
iii. As ointments and lotions e.g. Calamine
It may be noted that these drugs may also be available for internal application due to
gastrointestinal irritations. But they will not be considered topical products.
Md.
Imran
Nur
Manik

Topical Agents
Protective products
Talc:
Talc U.S.P. is a hydrous magnesium silicate (3MgO.4SiO2.H2O), sometimes containing
a small proportion of aluminum silicate.
The actual composition of talc is somewhat variable, containing
As magnesium polysilicate.
Properties:
i. Talc is a very fine, white or grayish white, crystalline powder.
ii. It is unctuous, adheres readily to the skin, and free from grittiness.
iii. It has a smooth, greasy feeling to the touch.
iv. It is odorless, tasteless and chemically inert.
v. It is insoluble in water, dilute acids, and dilute bases.
vi. It has very low adsorptive properties (which is an important consideration for its use as a
filtering aid, allowing filtration without danger of removing important constituents,
e.g., alkaloids, dyes, etc)
Uses of talc:
In spite of its low adsorptive properties, the inert nature of talc makes it a useful
lubricating, protective dusting powder. It can he used to prevent irritation due to friction, and to
protect areas from further irritation.
Insoluble Zinc compounds
Zinc Oxide (ZnO)
Properties:
1. ZnO is a very fine, odorless, amorphous, white or yellowish white powder.
2. It is free from gritty particles.
3. It gradually absorbs carbon dioxide from the air to form a basic zinc carbonate
[Zn2(OH)2C03].
4. It is insoluble in water and alcohol.
5. When freshly ignited, it should contain not less than 99.0% and not more than 100.5% of
ZnO.
6. When heated to 400°C or 500°C, the oxide develops a yellow color that disappears on
cooling.
7. Chemically, zinc oxide reacts with dilute acids such as dilute hydrochloric acid to form
water soluble products.
OHZnCl2HCIZnO 22 
Acidic solutions of zinc oxide exhibit the properties of zinc ion.
MgO → 28.1 - 31.2%
SiO2 → 57 - 61.7%
H2O → 3 - 7%
Md.
Imran
Nur
Manik

Topical Agents
Uses of zinc oxide:
1. his used as a protective in ointments (Zinc Oxide Ointment, U.S.P), pastes (Zinc Oxide
Paste, U.S.P.) and dusting powders in the treatment of skin ulcerations and other
dermatological problems.
2. As a dusting powder, it is frequently found in combination with oilier protectives or
antimicrobial agents, e.g., talc and boric acid.
3. Zinc oxide is the primary ingredient in Calamine (zinc oxide with a small proportion of
ferric oxide.)
Calamine:
Calamine U.S.P is zinc oxide with a small proportion of ferric oxide (ZnO.xFe2O3).
Properties:
1. The material is a fine powder, odorless, and practically tasteless.
2. It is insoluble in water, but almost completely soluble in mineral acids.
3. After ignition, it contains not less than 98.0% and not more than 100.5% of ZnO.
4. The presence of the ferric oxide [Fe2O3} gives the substance a pink color which varies
according to the method of preparation and the amount of ferric oxide present.
Uses of Calamine:
Calamine is classified by the U.S.P as a topical protective. It is used in dusting powders,
ointments, and lotions where it is applied to the skin for its soothing, adsorbent, protective
properties. Dermatological problems, particularly those involving the exudation of fluids,
respond reasonably well to the application of products containing calamine.
The only real difference between zinc oxide and calamine is the latter’s cosmetic acceptability.
Zinc stearate:
The U.S.P. describes Zinc stearate as a compound of zinc with a mixture of solid organic
acids obtained from rats, and consists chiefly or variable proportions of’ zinc stearate
([CH3(CH2)16CO2]2Zn) and zinc palmitate ([CH3(CH2)14CO2]2Zn). It contains the equivalent of
not less than 12.5% and not more than 14% of ZnO.
Properties:
1. It is a fine, white, bulky powder, free from grittiness and has a faint characteristic odor.
2. It is unctuous to the touch and readily adheres to the skin.
3. Zinc stearate either as a pure chemical or the official preparation, is insoluble in water,
alcohol and ether.
4. It can be hydrolyzed by heating in dilute mineral acids to form a soluble zinc salt and an
insoluble oily layer of stearic (and palmitic) acid.
Uses:
It is employed in dusting powders and ointments as a protective. It has a particular
advantage over many products, e.g., talc, in that it is not wetted by moisture. This property
makes the material more desirable in dermatological problems where large amounts of fluid are
exuded, because it will not form crusty patches over the areas being treated.
Titanium dioxide:
Titanium dioxide (Ti02) U.S.P. is a white amorphous, odorless, tasteless powder.
Md.
Imran
Nur
Manik

Topical Agents
Properties:
It is insoluble in water, hydrochloric acid, nitric acid and dilute sulfuric acid. Reaction of
titanium dioxide with hydrogen peroxide in dilute sulfuric acid produces titanium peroxide
(TiO3) which imparts an orange-red color to the solution. This reaction is used in the official
identification of the compound.
Uses:
The U.S.P. classifies Titanium Dioxide as a topical protective. This compound is used
primarily for its opacity due to its high refractive index (2.7). This high refractivity makes the
compound useful for screening out ultraviolet radiation; hence it is used in various sun screen
products. As a solar ray protective, it is used in a concentration of 5 to 25% in ointments or
lotions.
Using Aluminum as a protective agent:
Aluminum U.S.P is a very fine, free-flowing, silvery powder, free from gritty or
discolored partic1es having a density of 2.7. It is a very active element with a great affinity for
oxygen.
Aluminum is present in 10% concentration in Aluminum paste U.S.P which is prepared
using Zinc Oxide Ointment as the base is used as a protective to prevent irritation around
intestinal fistulae (an abnormal opening of the intestinal tract through the skin). A common
application is around the colostomy opening after surgery for intestinal cancer. The aluminum
protects the skin from the digestive action of intestinal fluids.
The metal reacts with atmospheric oxygen to form a superficial layer of aluminum oxide,
Al2O3 which protects the metal from further oxidation. It is insoluble in water & alcohol &
unreactive toward oxidizing acids, such as nitric acid & sulfuric acid. This is due once again to
the formation of a protective layer of aluminum oxide.
Antimicrobial agents:
Antiseptic: This term is generally applied to any agent which either kill or inhibits the growth
microorganisms i.e., bacteria, fungi, protozoa etc.
Germicide: The term germicide refers to a more specific agents which kill microorganisms, e.g.
bactericide (agents which kill bacteria), fungicide (agents which kill fungi), amoebecide etc.
Disinfectant: This term refers to the same type of activity as the term germicide. However its
usage differs in that it is applied to inanimate objects e.g. instruments, equipments, rooms etc.
Sterilization: Sterilization is the process to render an object completely free of microorganisms.
This frequently involves the use of chemicals or mechanical process (e.g. heat).
Mechanism of action of inorganic antimicrobial agents: The Mechanism of action of
inorganic antimicrobial agents can be divided into three general categories.
1. Oxidation
2. Halogenation
3. Protein precipitation
These represent the primary chemical interactions or reactions that occur between the agent and
microbial protein and result in the death of the microbe inhibition of its growth.
Md.
Imran
Nur
Manik

Topical Agents
Oxidation:
Those compounds capable of functioning as antimicrobial agents through oxidative
mechanism are generally nonmetals and certain type of anions. Most common among these are
hydrogen peroxide, metal peroxide, permanganates halogens etc (i.e. chlorine and iodine) and
certain oxo-halogen anions.
The effective oxidative actions of these compounds involves the reducing present in most
proteins e.g., the sulfhydryl (SH) group in cysteine.
Figure 1: An illustration of the action of oxidizing agents on protein containing sulfhydryl groups.
A. The protein before oxidation showing the presence of free sulfhydryl group.
B. The protein after oxidation showing the formation of a disulfide bridge between two-
SH groups.
The protein has a specific function in the microorganism. The formation of the disulfide
bridge will alter the conformation (shape) of the protein and thereby alter its function. The
overall change or destruction of function in specific proteins is responsible for the ultimate
destruction of the microorganism.
Halogenation:
The reaction occurring with antiseptics of hypo halite type and in particular hypo
chloride, OCl -
. These compounds cause chlorination with the peptide linkage of protein
molecule. An example of this is shown below-
This reaction is ultimately destructive to the function of specific proteins because the
substitution of the chlorine atom for the hydrogen produces changes in the forces (hydrogen
bonding) responsible for the proper conformation of protein molecule.
Protein precipitation
This type of mechanism involves the interaction of proteins with metallic ions. The
nature of the interaction is one of complexion in which the various polar groups on protein act
as ligands. The complexion of the metal results in a radical change in the properties of protein
or protein precipitant.
Protein-CO-NH-Protein
Protein-CO-NCl-ProteinMd.
Imran
Nur
Manik

Topical Agents
Examples:
Oxidative antimicrobial agents:
1. Hydrogen peroxide:
Hydrogen peroxide solution U.S.P contains in each 100 mL, not less than 2.5 g
and not more than 3.5 g of H2O2.
Mechanism of action:
The primary use of H2O2 solution is as a mild antiseptic. This action is produced when the
solution comes in contact with open or abraded tissue, exposing the chemical to the enzyme,
catalase. This enzyme catalyzes the decomposition of H2O2 to water and oxygen.
2H2O2 2H2O + O2
This oxygen acts as an oxidizing agent on bacteria providing antiseptic action particularly on
those organisms obliged to survive through anaerobic metabolism e.g. Escherichia coli,
Staphylococcus aureus etc.
Use:
 Gives mild antiseptic and cleansing effect on wounds.
 As mouthwash, gargle etc.
2. Zinc peroxide:
It is officially a mixture of Zinc peroxide, zinc carbonate and zinc hydroxide. This mixture
contains about 55% zinc peroxide.
It appears to be highly soluble in water, however it will slowly hydrolyze to produce zinc oxide
and hydrogen peroxide. This reaction is responsible for antimicrobial action, as the hydrogen
peroxide solution under the influence of catalase will release oxygen at the site of infection and
the remaining zinc oxide will exert astringent action.
Use:
 Antibacterial and mild astringent in the treatment of various kinds of wounds. Its
effectiveness is greater on anaerobic organisms particularly on those having a strict
restriction in their metabolic oxygen requirement.
 It has been used in oral infections. 25% suspension or direct application of powder may
be used.
3. Iodine solution N.F. and Iodine Tincture U.S.P:
Iodine solution and iodine tincture contain the same concentration of ingredients i.e. in each
100 mL they contain not less than 1.8 gm and not more than 2.6 gm of sodium iodide.
They differ in the nature of the solvent i.e. Iodine solution is aqueous having prepared with
purified water and Tincture contains approx. 50% alcohol as final solvent.
The antimicrobial agent common to both of these preparations is iodine.
The mechanism of action is likely to involve oxidation or iodination of microbial
protein.
Md.
Imran
Nur
Manik

Topical Agents
Uses:
 Topical antiseptic. Useful against bacterial and fungal infection.
 They have been used as antiseptic on the skin prior to surgery. Iodine tincture
may be more suitable for this purpose, since alcohol seems to improve the
penetration of iodine as well as providing some additional antibacterial effect.
 Iodine solution is preferred for application to wounds because the alcohol in
the tincture is irritating to open tissue.
 Tincture may be used to disinfect drinking water.
Protein Precipitant anti microbial agents:
1. Sulfurated potash:
Sulfurated potash N.F. is a mixture composed chiefly of potassium polysulfides and potassium
thiosulfate.
This preparation is prepared by heating potassium carbonate and sulfur to a temperature not
higher than 185°C.
3K2CO3 + 8S = 2K2S3 + K2S2O3 + 3CO2
Uses:
 It is an ingredient of white lotion.
 It is used as a parasiticide (scabicide) and in the treatment of acne and
psoriasis.

2. Selenium sulfide:
Selenium sulfide N.F. (SeS2) contains not les than 52% and not more than 55.5 % selenium.
Uses:
Used in shampoo in concentrations of 1-2.5% as an antiseborrheic.
3. Silver sulfadiazine:
H2N
O2
S N
Ag N
N
It is a white powder which is practically insoluble in water.
Uses:
 It combines the antibacterial properties of silver and sulfadiazine, particularly
effective against Pseudomonas aeruginosa.
 It is used in the treatment of wound sepsis in patients with secondary or
tertiary burns.
Astringents
Definition:
The agents which have binding or constricting properties/effects are known as
astringents. These compounds coagulate protein primarily on the surface of the cell, an action
that does not result in the death of the cell.
Md.
Imran
Nur
Manik

Topical Agents
Uses of astringents:
 They act as styptic to stop bleeding from small cuts by promoting coagulation of
blood and constricting capillaries and small blood vessels.
 They are used to reduce the volume from exudates from wounds and skin eruptions.
They are used as antiperspirants in deodorants to decrease secretion of perspiration
by constricting pores at surface of the skin.
 Corrosive effects of astringents can be used to remove undesirable tissue.
Astringent compounds:
 Aluminum chloride
 Aluminum sulfate
 White lotion
 Zinc chloride
 Zinc sulfate
Aluminum chloride (AlCl3.6H2O):
 It is a white or yellowish white, deliquescent, crystalline powder.
 It is odorless, sweet and has astringent taste.
 Its aqueous solutions are acid to litmus.
Uses:
 Local astringent
 Mild antiseptic
.
Aluminum sulfate [Al(SO4)3.14H2O]:
It is white crystalline powder; it may exist as shining plates or crystalline fragments. It is
stable in air, sweet in taste and it is odorless. It is soluble in water, insoluble in alcohol.
Uses:
 mild antiseptic
 The solutions contain 5-25% of the salt which are used for their astringent and
antiseptic properties.
White lotion:
It is a combination of zinc sulfate and sulfurated potassium diluted in purified water.
Preparation:
A solution of sulfurated potash (40gm in 450mL water) is added slowly zinc sulfate
(40gm in 450mL water) and then adding water to a volume of 1000 ml. The resulting product is
a suspension of zinc sulfides.
K2S + ZnSO4 = ZnS + K2SO4
The suspension is shaken properly before use because the precipitate tends to become
lumpy upon standing.
Md.
Imran
Nur
Manik

Topical Agents
Uses of white lotion:
 Parasiticide as it contain sulfide ion, S
 Astringent action as it contain Zn
 It is used in the treatment of acne vulgaris, seborrhea, dermatitis and other
dermatological problems.
Zinc chloride (ZnCl2):
As it contain Zn, a strong protein precipitant and strong astringent, this compound is
used as escharotic. (An agent which causes coating of tissue, aiding in the formation of scar
tissue to improve healing)
Use:
 It is mild antiseptic. The metal ion in this compound reacts with bacterial
enzymes and inhibits its action.
 The solution containing 0.5 to 2 % zinc chloride is applied as topical agents.
The lower concentration of the drug is used as a nasal spray to aid drainage from
infected sinuses.
 The compound act as a desensitizer of dentin. For this purpose, a 10% solution is
applied topically to the teeth.
Zinc Sulfate (ZnSO4.7H2O):
Major use of Zinc sulfate is as ophthalmic astringent in 25% aqueous solution.
The solution is used in 0.1mL doses to the conjunctiva.
Md.
Imran
Nur
Manik

Topical Agents Manik

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Topical Agents Manik

Similar to Topical Agents Manik (20)

More from Imran Nur Manik

More from Imran Nur Manik (20)

Recently uploaded

Recently uploaded (20)

Topical Agents Manik