ANTISEPTICS & DISINFECTANTS
Freeing of an article, surface or medium by removing or killing all micro-organisms including vegetative form of bacteria, spores, viruses, fungii
Destruction or inhibition of growth of all pathogenic organisms (bacteria, viruses, fungii) on non living surfaces
If spores are also killed process is Sterlization
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
2.Non staining & good odour
3.Active against all pathogens
4.Active in presence of pus, blood & exudates
6.Non irritating to tissues / non corrosive
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
–phenol, cresol, hexachlorophene, chlorohexylenol (dettol)
–Iodine, chlorine, chlorophores.
Earliest used, reference standard
–injures tissues & cells at high conc causes skin burn
–denaturating bacterial protiens.
–To disinfect urine, faeces, pus, burns.
Extremely irritating, corrosive
Methyl Derivative of phenol, less damaging to tissues than phenol.
3-10 times more active
used for disinfection of utensils, excreta & for washing hands.
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%
Commonly incorporated in soap
Effectively only against Gm+ve
Slow but persistant action
>2% preparations banned
– 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
–liberates nascent oxygen which oxidizes necrotic matter & bacteria.
–Helps in loosening & removing slough, ear wax etc.
–Widely used drug for acne.
–liberates O2 in presence of water which kills bacteria, specially anaerobes
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
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.
potent germicide. Kills pathogens in 30 sec. used to disinfect urban water supplies.
0.1 to 0.25 ppm
(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
– 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
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)
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
–Antiseptic, cleansing agent at 40-90% conc.
–Act by precipating bacterial proteins
– Irritant, should not be applied on mucous membrane, ulcers, open wounds.
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
weak antiseptic , bacteriostatic.
used for mouth wash, irrigation eyes, glossitis.
Adverse effect: vomiting ,abdominal pain on systemic absorption.
Silver sulphadiazine is active against pseudomonas seen in burns patient.
Silver nitrate highly active against gonococci
Mild antiseptic, used as eye wash, ear drops.
– Active against bacteria (gram + ve), fungi
–Used on chronic ulcers, furunculosis, bed sores, ring worms.
–Active against gram +ve bacteria & gonocci
–suitable for chronic ulcers & wounds
–Do not retard healing, non irritant
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
(3) BENZYL BENZOATE
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.
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.
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.
low cure rates
Better results if applied for 5 days in children
Less irritation and toxicity
May be preferred in children as second choice
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.