Antiseptics and disinfectants


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  • Germicide is an agent which covers both these agents Seimelweiss: chlorinated lime. Lister: phenol
  • Chemically stable and cheap
  • Static in 0.2 & cidal in >1% concAccidental poisoning: rapidly absorbed penetrate intact skin, GIT corossion pain, collapse, decreased body temperature, convulsions and death by respiratory failure. Not used as antiseptoc due to corrosive nature
  • Wider margin of safety
  • 0.8% skin cream and soap, 1.4% for mouth wash These preparations loose activity if diluted or kept in water for long period of time Loose activity if diluted in water and kept for long time
  • Around 1970 fatalities in US due to
  • includes k permanganate, H2O2 , benzoylperxide.Except atropine and cocaine which are not efficiently oxidized
  • Liberates nascent oxygen which oxidizes necrotic matter and bacteria 30 % solution produces 10 volumes of oxygen much of which escapes in molecular form Catalase present in tissue speeds decomposition resulting in faomoing and helps loosening and removing slough Benzoyl peroxide: induces desquamation, the comedones are shed & irritant fatty acids are reduced. Mild irritant, burning sensation is often felt .
  • Compounds that slowly release hypochorous acid
  • Prevention of gingivitisHow ever it may leave unpleasant taste and on repeated administration may cause brownish discoloration of teeth
  • Many gram negative bacteria like pseudomonas,mycobcaterium TB and spores are eresistantSoaps are anionic and neutralize their action while alcohol potentiates it, spread through oil and grease and cleansing properties
  • Can be medivcated by adding other antiseptics
  • Rapidity of action increases upto 70% and decreases above 90%Cotton swab soaked in 70% alcohol rubbed on skin kill 90% of bacteria in 2 min has been used before hypodermic injection
  • Diluted to 4 % and is used for hardening tissues Eczematoid reactions can reactions can occur
  • 10% ointment borocide is available for cuts and abrasion Acetic acid is relatively weak antiseptic only above 5% pseudomonas is susceptible . It is occasionally used for sub burn dressing and for douche in 1-3 % strength s
  • mercuric compounds - poor antiseptic & bacteria spore survive after contact. Not used
  • Triple dye lotion contains gentian violet brilliant green and acriflavineTRIPLE DYE LOTION: Contain gentian violet + brilliant green + Acriflavin used for burns & dressing umblical stump in neonates
  • Maximum 92 % cure rate
  • For pediculosis it should be applied to scalp taking care not to enter the eyes and washed off after 24 hours now it is second choice drug for scabies and seldom used for pediculosis its combination with lindane is highly effective
  • Antiseptics and disinfectants

    2. 2. Sterlization• Freeing of an article, surface or medium by removing or killing all micro-organisms including vegetative form of bacteria, spores, viruses, fungii
    3. 3. 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
    4. 4. Antiseptics• These are chemical substances which inhibit the growth or kill micro- organisms on living surfaces such as skin & mucous membrane.
    5. 5. Properties of good antiseptic/ disinfectant1. Cidal2. Non staining & good odour3. Active against all pathogens4. Active in presence of pus, blood & exudates5. Rapid acting6. Non irritating to tissues / non corrosive7. Non absorbable8. Non sensitizing/
    6. 6. 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
    7. 7. Classification• Phenol derivatives: • Alcohols: – phenol, cresol, hexachlorophene, – Ethanol, isopropanol chlorohexylenol (dettol) • Aldehyde:• Oxidizing agents: – Formaldehyde – Hydrogen peroxide. • Acids:• Halogens: – Acetic acid, boric acid – Iodine, chlorine, chlorophores. • Metallic salt:• Biguanides: – Mercuric compounds , silver – Chlorhexidine. & zinc salts • Dyes:• Quaternary ammonium: – Gentian violet, acriflavine – Cetrimide.
    8. 8. 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
    9. 9. 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.
    10. 10. 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%
    11. 11. Hexachlorophene• Commonly incorporated in soap• Effectively only against Gm+ve• Slow but persistant action• >2% preparations banned
    12. 12. 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
    13. 13. Oxidizing agentsHydrogen 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
    14. 14. Halogens• Iodine,• Iodophores,• Chlorine,• Chlorophores
    15. 15. Iodine• Rapidly acting broad spectrum (bacteria, fungi,virus)• Acts by iodinating and oxidizing microbial protoplasm.• Used for cuts, degerming skin beforesurgery.• Adverse effect: cause burns & blisters
    16. 16. Iodophores• Known as povidine iodine.• Non toxic, non staining prolonged action.• Used on boils, furunculosis, burns, ulcers, tinea, surgica l srub, disinfecting surgical instruments, non specific vaginitis.
    17. 17. Chlorine• potent germicide. Kills pathogens in 30 sec. used to disinfect urban water supplies.• 0.1 to 0.25 ppm
    18. 18. 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
    19. 19. BiguanidesChlorhexidine: (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
    20. 20. 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)
    21. 21. 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
    22. 22. 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.
    23. 23. 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
    24. 24. AcidsBoric acid• weak antiseptic , bacteriostatic.• used for mouth wash, irrigation eyes, glossitis.• Adverse effect: vomiting ,abdominal pain on systemic absorption.
    25. 25. Metallic saltsSILVER COMPOUNDS• Silver sulphadiazine is active against pseudomonas seen in burns patient.• Silver nitrate highly active against gonococciZN SALTS• Mild antiseptic, used as eye wash, ear drops.
    26. 26. DyesGentian 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
    27. 27. Ectoparasiticides• These are drugs used to kill parasites that live on body surfaces lice → cause pediculosis (hair infection) mites → cause scabies(skin infection)
    29. 29. 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.
    30. 30. 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.
    31. 31. 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.
    32. 32. 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
    33. 33. 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.