Antiseptic & Disinfectant

Antiseptic & Disinfectant

Antiseptics: Antiseptics are the agents that are used on living tissues & act as antimicrobial but don’t kill them necessarily.

Disinfectants: - Disinfectants are agents which are applied on inanimate objects & kill the microbes outright.     

When the word end with

 -cide   means to kill the microbes e.g. bactericide means to kill bacteria

  -stat means to prevent the growth (multiplications) of microbes

E.g. bacteriostatic means to prevent the growth of bacteria.

Classification of Antiseptic & Disinfectant:-

Phenols & related compound: Phenol, Chlorocresol. Chloroxylenol, Hexachlorophene

Alcohols & related compound: Ethanol, Isopropyl alcohol

Aldehyde: Formaldehyde

Carboxylic acid and their derivatives: Benzoic acid, Methyl P- hydroxy benzoate.


a) Chlorophors: e.g. Chloramines.

b) Iodophors:   e.g. Povidone –iodine, Iodoform

Heavy metal compound:

a) Organic mercurial’s:  Thiomarsal

b) Silver compound: Silver sulphadiazine, silver protein

Quaternary ammonium compound /cationic compound: Benzalkonium chloride, cetrimide.

Dyes: Proflavin, brilliant green.

Miscellaneous agents

a) Topical – Nitorfurazone ,Icthamol

b) Urinary antiseptic –Nitrofurantoin

Proflavin /Proflavin Hemisulphate / Neutral Hemisulphate

Structure of Proflavin:

3, 6 acridine diamine/3, 6 Diamino acridine, 

It is an acridine derivative.

The acridine cation is largely responsible for antibacterial activity.

The presence of two amino group, at position 3 and 6 brings about the resonance stabilization of the cation which increase the base strength.

This lead to the higher conc. Of cation at pH (7.3) thus providing increased bacteriostatic activity.     

Physical Properties of Proflavin:

It occurs as orange to red crystalline hygroscopic powder.

It is odourless.

It is sparingly soluble in water.

Very soluble in hot water.

It is practically insoluble in a chloroform and ether.

Chemical properties of Proflavin:

When it is treated with potassium fericynide in slightly acidic medium it is precipitate as its fericynide salt.

K3Fe (CN) 6 +3HCL       -------------         H3Fe (CN) 6+3KCL

Stability &Storage of Proflavin:

 It is hygroscopic and affected by light; hence it is stored in tightly closed light resistant container.

Uses of Proflavin:

It is slow acting antiseptic.

It is effective against many gram positive and gram negative bacteria.

It is used in the treatment of infected wound.

For the dressing of wound and burns.

For the treatment of local infection of external ear, mouth, throat and skin.

Pharmaceutical formulations: Proflavine cream

Brand names: Triple Dye, Kerr Triple dye

Benzalkonium chloride

Structure of Benzalkonium chloride:

It is the mixture of alkyl benzyl dimethyl ammonium chloride .in this alkyl group has 8 to 18 carbon atoms.

I.e. R= C8H5 to C18H37

Quaternary ammonium compound is the derivatives of an ammonium salt having general formula N+R4X-

Where R= alkyl or other organic radical, X= acid radicals like CL, Br, OH

Properties of Benzalkonium chloride:

It is white to pale yellow gel.

It has aromatic odour.

Very bitter in taste.

It is miscible with water.

The aqueous solution is alkaline to litmus and foams strongly on shaking.

Stability and Storage of Benzalkonium chloride:

It is decomposed by alkali hydroxide and affected by light .hence it is stored in tightly closed light resistant containers.

Uses of Benzalkonium chloride:

It is an antiseptic and detergent

For cleansing intact skin.

For irrigation of bladder, urethra and vagina.

To get relief from painful infection of mouth and throat.

It is also used as preservative in eye drops.

Pharmaceutical formulations: Benzalkonium chloride, Benzalkonium chloride lozenges.

Brand names: Azep Nasal, Tanac, Herpetrol (benzalkonium chloride/menthol topical)


Structure of Cetrimide:

It is cetyl trimethyl ammonium bromide.

In smaller proportion; it contains dodecyl and hexadecyl trimethyl ammonium bromide.  

Properties of Cetrimide:

It is white or creamy white free flowing powder.

It has faint and characteristic odour

It is freely soluble in water.

Soluble in alcohol.

Practically insoluble in ether.

Storage of Cetrimide:

Stored in well closed containers.

Uses of Cetrimide: 

It is an antiseptic and detergent and hence it is used as

To treat the burns and wounds.

To remove scabs


Structure of Phenol:

Properties of Phenol:

It is colourless liquid which may turn pinkish blue on keeping.

It has characteristic, somewhat aromatic odour.

It is caustic.

It gives clear solution when 15, parts of water is added to 1 part to it.

It is miscible with glycerin.

Storage & Stability of Phenol:

Stored in a well closed light resistant container.

The crystal may get deposited if stored at a temperature below 4 degree C.

In such cases it should be completely melted before use.

Uses of Phenol: 

It is bactericidal and germicidal. It is used

For a dressing of small wound.

To get relief from itching (due to anesthetic property.)

As an analgesic in dentistry

As an antiseptic and analgesic in mouth ulcers and tonsillitis.

In the treatment of boils in ears.


Properties of Chloroxylenol:

It occurs as a white crystalline powder.

It has characteristic odour.

It is practically insoluble in water.

Soluble in alkali hydroxide solution, fixed oil, alcohol.

It is volatile in steam.

Stability and storage of Chloroxylenol:

It is affected by light; hence it is stored in tightly closed light resistant container.

Uses of Chloroxylenol:

It is relatively non-irritant antiseptic, for cuts, wound and abrasions.

It is also used as a disinfectant.

Pharmaceutical formulations: Chloxylenol solutions

Brand names: Fairgenol


Structure of Chlorocresol:

Chemical names: 4-Chloro-3-methylphenol

Chemistry of Chlorocresol:

It is substituted phenol in which methyl group and chloro group are attached at C3 and C4 respectively.

Introduction of –CH3 group at 3 positions and chloro group at 4 position increase antibacterial activity.

The disadvantage is that water solubility is reduced.

Physical properties of Chlorocresol:

It occurs as colourless or faintly coloured crystals.

It having characteristic odour.

It is slightly soluble in water, soluble in hot water

It is readily soluble in alcohol and ether.

It is steam volatile.

Stability and storage of Chlorocresol:

It is oxidized by air or oxygen and hence it is stored in tightly closed containers.

Uses of Chlorocresol:

Used as powerful bactericide and fungicide.

Used as preservative in creams in pharmaceutical preparations.

Pharmaceutical preparations:

Chlorocresol solution


Properties of Formaldehyde Solution:

It is colourless liquid.

It’s having characteristics irritating odour.

It’s having burning taste.

It is miscible with water and alcohol. 

Chemical properties of Formaldehyde Solution:

When formaldehyde solution is treated with 2% sulphuric acid and the vapor are condensed quickly, a trimer, trioxane or trioxymethylene is formed.

When formaldehyde solution is evaporated, a white friable mass of polyformaldehyde is obtained.

Stability and storage of Formaldehyde Solution:

It is oxidized readily in air and oxygen.

It undergoes polymerization on storage and the process is accelerated in cool place.

Hence it is stored in tightly closed containers in moderately warm place.

Contact with rubber, plastic, polythene is avoided.

Uses of Formaldehyde Solution: 

it is powerful antibacterial agent hence it is used as

In treatment of chronic skin disease.

As an antiseptic (in mouthwashes and gargles).

To disinfect rooms, instruments, clothing, hands or site of operation.

It is also used as preservative for pathological specimens.

Hexamine (formaldehyde + ammonia) use as urinary antiseptics.

Pharmaceutical formulations: Formaldehyde Lotions, Formaldehyde Gels

Brand names: Kanpip


Structure of Hexachlorophene:

Chemistry of Hexachlorophene:

It is biphenolic Compound.

Two phenol rings are bridged through a methylene group (-CH2-) through C2 of each.

It contains 6 chlorine atoms attached to 3, 3’, 5, 5’, 6 and 6 carbon atoms.

Due to higher chlorine contents and less water solubility it is used as antiseptic in low concentration and activity is prolonged.

Properties of Hexachlorophene:

It occurs as white or pale buff crystalline powder.

It is odourless.

It is practically insoluble in water and soluble in dilute solution of alkali hydroxide.

Chemical Properties of Hexachlorophene:

When it is treated with sodium hydroxide at pH 9 it is converted to monosodio derivatives.

It gives purple colour with ferric chloride.

Storage of Hexachlorophene:

It is affected by light hence it is stored in tightly closed, light resistant containers.

Uses of Hexachlorophene: 

It has antibacterial property hence it is used as,

To reduce the bacterial flora on skin (in the form of soaps)

To reduce the bacterial infections

To disinfect the hands of surgeon

Pharmaceutical formulations: Concentrated hexachlorophene solution, dusting powder, drench (mixture), cleansing emulsion, and liquid soap.

Brand names: Sterzac, Zalpon


Physical properties of Nitrofurantion:

It occurs as yellow crystal or crystalline powder.

It is odourless.

It has bitter taste.

It is very slightly soluble in water.

Storage of Nitrofurantion:

It is affected by light hence it is stored in tightly closed

Light resistant containers temperature not exceeding 25 degree Celsius.

Uses of Nitrofurantion:

It is broad spectrum antibacterial agents.

It is used in treatment of urinary tract infection.

Pharmaceutical formulations: Nitrofurantoin suspension, capsules, tablets

Brand names: Furadantin, Urantoin, NFT

Antiseptic & Disinfectant Question banks:

Define and classify antiseptic and disinfectants giving a suitable example.

Write the structure and describe Chemistry, Properties, and Uses of Proflavine or Chlorocresol.

Give the pharmaceutical preparations and uses and brand names of following  

a.       Proflavine

b.      Benzalkonium chloride

c.       Chloroxylenol

d.      Nitrofurantoin

e.      Hexachlorophene

Write the structure and chemical name of acridine

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