ANTISEPTICS & DISINFECTANTS

• Sterlization

• Freeing of an article, surface or medium by removing or killing all micro-organisms including vegetative form of bacteria, spores, viruses, fungii

• Disinfection

• Destruction or inhibition of growth of all pathogenic organisms (bacteria, viruses, fungii) on non living surfaces

• If spores are also killed process is Sterlization

• Antiseptics

• These are chemical substances which inhibit the growth or kill micro-organisms on  living surfaces such as skin & mucous membrane.

Properties of good antiseptic/ disinfectant

1.Cidal

2.Non  staining &  good odour

3.Active against all pathogens

4.Active in presence of pus, blood & exudates

5.Rapid acting

6.Non irritating to tissues / non corrosive

7.Non absorbable

8.Non sensitizing/

• Mechanisms of action of antiseptic and disinfectants

• Oxidation of bacterial protoplasm

–Potassium permagnate, H202, Halogens

• Co-agulation (denaturation) of bacterial proteins & disrupt cell membrane

–Phenols, chlorhexidine, alcohols, aldehydes

• Detergent like action ↑ permeability of bacterial cell membrane

–Cetrimide, soaps

• Classification

• Phenol derivatives:

–phenol, cresol, hexachlorophene, chlorohexylenol (dettol)

• Oxidizing agents:

–Hydrogen peroxide.

• Halogens:

–Iodine,  chlorine,  chlorophores.

• Biguanides:

–Chlorhexidine.

• Quaternary ammonium:

–Cetrimide.

• Phenol

• Earliest used, reference standard

• Protoplasmic poison,

–injures tissues & cells at high conc causes skin burn

• MOA:

–denaturating bacterial protiens.

• USES :

–To disinfect urine, faeces, pus, burns.

• Extremely irritating, corrosive

• CRESOL (Lysol)

• Methyl Derivative of phenol, less damaging to tissues than phenol.

• 3-10 times more active

• used for disinfection of utensils, excreta & for washing hands.

• Chloroxylenol (Dettol)

• Phenol derivative

• Does not co-agulate proteins,

• Non corrosive,Non irritating to skin

• Commercial 4.8 % solution used for surgical antisepsis

• Skin cream and soap: 0.8%

• Mouth wash 1%

• Hexachlorophene

• Commonly incorporated in soap

• Effectively only against Gm+ve

• Slow but persistant action

• >2% preparations banned

• Oxidizing agents

• Potassium permagnate:

– Purple crystals, highly water soluble, liberates oxygen which oxidizes bacterial protoplasm.

–Used for gargling, irrigating wounds, urethra (condy`s lotion diluted solution of 1:4000  to 1:10,000 )

–High conc cause burns

–It is also used to disinfect water in ponds.

–Stomach wash in alkaloidal poisoning

• Oxidizing agents

Hydrogen Peroxide

–liberates nascent  oxygen which oxidizes necrotic matter & bacteria.

–Helps in loosening  &  removing  slough,  ear wax etc.

Benzoyl Peroxide

–Widely used drug for acne.

–liberates O2 in presence of water which kills bacteria, specially anaerobes

• Halogens

• Iodine,

• Iodophores,

• Chlorine,

• Chlorophores

• Iodine

• Rapidly acting broad spectrum (bacteria, fungi,virus)

• Acts by iodinating and oxidizing microbial protoplasm.

• Used for cuts, degerming skin before surgery.

• Adverse effect: cause burns & blisters

• Iodophores

• Known as povidine iodine.

• Non toxic, non staining prolonged action.

• Used on boils, furunculosis, burns, ulcers, tinea, surgical srub, disinfecting surgical instruments, non specific vaginitis.

• Chlorine

• potent germicide. Kills pathogens in 30 sec. used to disinfect urban water supplies.

• 0.1 to 0.25 ppm

• Cholorophores

(1)  Chlorinated lime (bleaching powder)

–obtained by action of chlorine on lime.

–used to disinfect drinking water

(2)  Sodium hypochlorite

– Powerful  disinfectant used in dairies for milk  cans.

–Too Irritant to be used as antiseptic.

–Root canal therapy in dentisry

• Biguanides

Chlorhexidine: (Savlon)

– Acts by disrupting bacterial cell membrane & denaturation of bacterial proteins

– Non irritant ,more active against gram +ve     bacteria.

–Used in for surgical scrub, neonatal bath, mouth wash &  general skin antiseptic.

–Most widely used antiseptic in dentisry 0.12-0.2% oral rinse or 0.5 -1 % tooth paste

• Quarternary ammonium antiseptics cetrimide

• Detergents: Cidal to bacteria, fungi & viruses.

• Act by altering permeability of cell membrane

• Efficiently remove dirt and grease

• Widely used as antiseptics & disinfectants for surgical   instruments, gloves etc

• Combined with chlorhexidine (savlon)

• Soaps

• Anionic detergents

• Weak antiseptics with cleansing action

• Washing with soap and warm water one of the most effective methods of preventing disease transmission

• Affect only Gm+ bacteria

• Alcohols

• Ethanol

–Antiseptic, cleansing agent at 40-90% conc.

–Act by precipating bacterial proteins

– Irritant, should not be applied on mucous membrane, ulcers, open wounds.

• Aldehydes (Formaldehyde)

• Used for fumigation.

• 37 % aqueous solution called as formalin.

• Protoplasmic poison , denaturates protiens.

• Used for preserving dead tissues.

• Use as antiseptic  restricted due to bad odour & irritation

• Glutaraldehyde is a better sterlizing agent

• Acids

Boric acid

• weak antiseptic , bacteriostatic.

• used for mouth wash, irrigation eyes, glossitis.

• Adverse effect: vomiting ,abdominal pain on systemic absorption.

• Metallic salts

SILVER COMPOUNDS

• Silver sulphadiazine is active against pseudomonas seen in burns patient.

• Silver nitrate highly active against gonococci

ZN SALTS

• Mild antiseptic, used as eye wash, ear drops.

• Dyes

Gentian violet:

– Active against bacteria (gram + ve), fungi

–Used on chronic ulcers, furunculosis, bed sores, ring worms.

Acriflavine

–Active against  gram +ve bacteria & gonocci

–suitable for chronic ulcers & wounds

–Do not retard healing, non irritant

• Ectoparasiticides

• These are drugs used to kill parasites that live on body surfaces

lice → cause pediculosis (hair infection)

mites → cause scabies(skin infection)

• Drugs used are

(1)  PERMETHRIN

(2)  LINDANE

(3) BENZYL BENZOATE

(4) IVERMECTIN

(5) CROTAMITON

(6) SULFUR

• Permethrin

• Broad spectrum causes neurological paralysis in insects.

• 100 % cure rate nearly

• Single application needed in most  cases.

• Few patients experience itching ,burning.

• first drug of choice for scabies & pediculosis.

Scabies: apply  all over the body except face & head . Wash  after 8- 12 hrs.

Head louse: massage about 30 g in to scalp  and wash  after  10 min.

• Lindane

• Broad spectrum insecticide which kills lice and mites by penetrating their chitinous cover

• Properties similar to permethrin.

• Cure rate low & resistance seen.

• Disadvantage: being lipid soluble CNS toxicity like vertigo , convulsions seen.

• Application similar to permithrin.

• combination with benzyl benzoate is more effective.

• Benzyl benzoate

• Oily liquid with aromatic smell.

• Cure rate 76 – 100% ; second application required after 24 hrs.

• Toxicity is low. Application similar to permethrin.

• Use has declined due to skin irritation.

• Contra indicated in children because of neurological symptoms & skin irritation.

• combination with lindane highly effective.

• Crotamiton

• low cure rates

• Better results if applied for 5 days in children

• Less irritation and toxicity

• May be preferred in children as second choice

• Ivermectin

• Anti helminthic drug which has been recently found effective against scabies & pediculosis.

• A single 0.2 mg /kg ( 12mg in adults) has 91- 100 %  cure rate.

• Contra indicated in children < 5yrs , preganant & lactating women.

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