Hello friends. In this PPT I am talking about antiseptics, disinfectants. If you like it, please do let me know in the comments section. A single word of appreciation from you will encourage me to make more of such videos. Thanks. Enjoy and welcome to the beautiful world of pharmacology where pharmacology comes to life. This video is intended for MBBS, BDS, paramedical and any person who wishes to have a basic understanding of the subject in the simplest way.

1. Antiseptics, Disinfectants and
other locally acting drugs
Dr. Karun Kumar
Senior Lecturer
Dept. of Pharmacology

2. • Antiseptics  Agents used on living surfaces (skin,
mouth)
• Disinfectants  Agents used for inanimate objects
(instruments, water supply)
• Germicide  Covers both
• Sterilization  Complete killing of all forms of
microorganisms
• Disinfection  Reduction in the number of viable
pathogenic microbes to a level that they do not pose
a risk to individuals with normal host defence.

3. • A good antiseptic/disinfectant should be:
1. Chemically stable.
2. Cheap.
3. Nonstaining with agreeable colour and odour.
4. Cidal and not merely static, destroying spores as
well.
5. Active against all pathogens—bacteria, fungi,
viruses, protozoa.
6. Require brief time of exposure.
7. Active even in the presence of blood, pus, exudates
and excreta.

4. • An antiseptic in addition should be:
1. Rapid in action and exert sustained protection.
2. Nonirritating to tissues, should not delay healing.
3. Nonabsorbable, produce minimum toxicity if
absorbed.
4. Nonsensitizing (no allergy).
5. Compatible with soaps and other detergents.

5. Spectrum of activity
• Selective  Hexachlorophene, chlorhexidine,
quaternary ammonium antiseptics, gentian violet
and acriflavin are more active on gram-positive than
gram-negative bacteria
• Silver nitrate is highly active against gonococci
• Benzoyl peroxide is highly active against P. acnes

6. Mechanisms of action
1. Oxidation of bacterial protoplasm
2. Denaturation of bacterial proteins including
enzymes
3. Detergent like action increasing permeability of
bacterial membrane

7. • Factors modifying the activity of germicides
1. Temperature and pH
2. Period of contact with the microorganism.
3. Nature of microbe involved.
4. Size of inoculum.
5. Presence of blood, pus or other organic matter

8. • Potency of a germicide  Expressed by its phenol
coefficient or Rideal Walker coefficient (Ratio of the
minimum concentration of test drug required to kill a
24 hour culture of B. typhosa in 7.5 minute at 37.5°C
to that of phenol under similar conditions)
• Therapeutic index of an antiseptic  Comparing the
concentration at which it acts on microorganisms
with that which produces local irritation, tissue
damage or interference with healing.

9. Classification
1. Phenol derivatives  Phenol, Cresol,
Hexylresorcinol, Chloroxylenol, Hexachlorophene
2. Oxidizing agents  Pot. permangnate, Hydrogen
peroxide, Benzoyl peroxide
3. Halogens  Iodine, Iodophores, Chlorine,
Chlorophores
4. Biguanide  Chlorhexidine
5. Quaternary ammonium (Cationic)  Cetrimide,
Benzalkonium chloride, Dequalinium chloride

10. 6. Soaps  of Sod. and Pot.
7. Alcohols  Ethanol, Isopropanol.
8. Aldehydes  Formaldehyde, Glutaraldehyde.
9. Acids  Boric acid, Acetic acid.
10. Metallic salts  Silver nitrate, Silver sulfadiazine,
Mild silver protein, Zinc sulfate, Calamine, Zinc oxide.
11. Dyes  Gentian violet, Acriflavine, Proflavine.
12. Furan derivative  Nitrofurazone

11. Phenol derivatives
1. Phenol
2. Cresol
3. Hexylresorcinol
4. Chloroxylenol
5. Hexachlorophene
6. Triclosan

12. Phenol (Carbolic acid)
• Antiseptic (static at 0.2%, cidal at >1%, poor action
on bacterial spores)
• Protoplasmic poison, injuring microbes and tissue
cells alike— at higher concentrations causes skin
burns and is a caustic
• Acts by disrupting bacterial membranes and
denaturing bacterial proteins

13. • Organic matter diminishes its action slightly while
alkalies and soaps do so profoundly (carbolic soaps
are not more germicidal than soap itself)
• Used to disinfect urine, faeces, pus, sputum of
patients and is sometimes included in antipruritic
preparations because of its mild local anaesthetic
action

14. Cresol
• It is methyl-phenol; more active (3–10 times) and
less damaging to tissues.
• Used for disinfection of utensils, excreta and for
washing hands

15. Hexylresorcinol
• It is a more potent derivative of the phenolic
compound resorcinol that is odourless and
nonstaining
• Used as mouthwash, lozenge and as antifungal

16. Chloroxylenol
• Commercial 4.8% solution (DETTOL) is prepared in
9% terpinol and 13% alcohol; used for surgical
antisepsis.
• A 0.8% skin cream and soap, 1.4% lubricating
obstetric cream (for vaginal examination, use on
forceps, etc.), and a mouthwash (DETTOLIN 1% with
menthol 0.45%) are also available.
• These preparations lose activity if diluted with water
and kept for a time

17. Triclosan
• Bactericidal (denaturation of membrane bound
enzymes)
• Hydroalc. Soln. is a mixture of phenolic volatile oils
thymol, menthol, eucalyptol along with benzoic acid
is a popular mouthwash LISTERINE
• Widely used for bad breath, dental plaque &
gingivitis

18. Hexachlorophene
• Chlorinated phenol acts by inhibiting bacterial
enzymes and (in high conc.) causing bact. Lysis
• Odourless, nonirritating and does not stain
• Activity is ↓ by organic matter but not by soap
• Commonly incorporated in soap and other cleansing
antiseptics for surgical scrub, patient’s skin, etc., but
is narrow spectrum; kills gram-positive but not gram-
negative bacteria or spores

19. • Degerming action is slow but persistent due to
deposition on the skin as a fine film that is not
removed by rinsing with water
• Incorporated in toilet products, it is a good
deodorant

20. Oxidizing agents
1. Pot. Permangnate
2. Hydrogen peroxide
3. Benzoyl peroxide

21. Potassium permanganate
• Occurs as purple crystals, highly water soluble,
liberates oxygen which oxidizes bacterial protoplasm.
• The available oxygen and germicidal capacity is used
up if much organic matter is present—the solution
gets decolourised
• A 1:4000 to 1:10,000 solution (Condy’s lotion) is used
for gargling, douching, irrigating cavities, urethra and
wounds.

22. • The action is rather slow and higher concentrations
cause burns and blistering—popularity therefore has
declined.
• It has also been used to disinfect water (wells,
ponds) and for stomach wash in alkaloidal poisoning
(except atropine and cocaine which are not
efficiently oxidized).
• It promotes rusting and is not good for surgical
instruments.

23. Hydrogen peroxide
• It liberates nascent oxygen which oxidizes necrotic
matter and bacteria
• A 3.0% solution produces 10 volumes of oxygen,
much of which escapes in the molecular form
• Catalase present in tissues speeds decomposition
resulting in foaming—helps in loosening and
removing slough, ear wax, etc.
• Hydrogen peroxide has poor penetrability and a
weak, transient antiseptic action

24. • Hydrogen peroxide mouthwash has been employed
in acute necrotizing gingivitis (anaerobic bacteria)
• Also used in periodontal disease
• A 20-30% solution in water or ether has been used as
a bleaching agent on teeth
• Frequent use can produce oral ulcers

25. Benzoyl peroxide
• Specifically active against P. acnes and used on acne
vulgaris

26. Halogens
1. Iodine
2. Iodophores
3. Chlorine
4. Chlorophores

27. Iodine
• Rapidly acting, broad-spectrum (bacteria, fungi,
viruses) microbicidal agent
• Acts by iodinating and oxidizing microbial
protoplasm.
• A 1 : 20,000 solution kills most vegetative forms
within 1 min. Even bacterial spores are killed with
higher concentrations/longer contact.
• Organic matter retards but does not abolish its
germicidal action.
• Solid iodine is corrosive, stronger solutions (> 5%)
cause burning and blistering of skin.

28. • Tincture iodine (2% in alcohol) stings on abrasions. It
is used on cuts, for degerming skin before surgery,
and to treat ring worm, etc.
• Mandel’s paint (1.25% iodine dissolved with the help
of Pot. iodide forming soluble I¯-ions) is applied on
sore throat.
• A nonstaining iodine ointment (IODEX 4%) is popular
as antiseptic and counterirritant.
• Some individuals are sensitive to iodine—rashes and
systemic manifestations occur in them.

29. Iodophores
• Soluble complexes of iodine with large molecular
organic compounds that serve as carriers—release
free iodine slowly.
• The most popular—Povidone iodine: is nonirritating,
nontoxic, nonstaining and exerts prolonged
germicidal action.
• Treated areas can be bandaged or occluded without
risk of blistering.

30. • It is used on boils, furunculosis, burns, otitis externa,
ulcers, tinea, monilial/trichomonal/ nonspecific
vaginitis and for surgical scrubbing, disinfection of
endoscopes and instruments.
• In dentistry, 1% povidone iodine oral rinse is
employed for gingivitis

31. Chlorine
• A highly reactive element and a rapidly acting potent
germicide
• 0.1–0.25 ppm kills most pathogens (but not M.
tuberculosis) in 30 sec
• Degerming action is soon exhausted, and it lacks
substantivity
• Used to disinfect urban water supplies

32. • Organic matter binds chlorine, so that excess has to
be added to obtain free chlorine concentration of
0.2–0.4 ppm
• This is known as the ‘chlorine demand’ of water
• Chlorine is more active in acidic or neutral medium

33. Chlorophores
• Compounds that slowly release hypochlorous acid
(HOCl)
• Ease of handling  Used in pref. to gaseous chlorine.
1. Chlorinated lime (bleaching powder)  Obtained
by the action of chlorine on lime
• Mixture of calcium chloride and calcium hypochlorite
• Used as disinfectant for drinking water, swimming
pools and sanitizer for privies, etc.
• Bleaching action is utilized for removing stains from
teeth & for their cosmetic whitening

34. 2. Sodium hypochlorite solution  Contains 4–6%
sodium hypochlorite.
• Powerful disinfectant used in dairies for milk cans,
other equipment and for infant feeding bottles.
• It is used in root canal therapy in dentistry.
• Irrigation of root canal with 2% Sodium hypochlorite
solution loosens & dissolves dead tooth pulp in
addition to exerting rapid antisepsis

35. Chlorhexidine (Biguanide)
• A powerful, nonirritating, cationic antiseptic that
disrupts bacterial cell membrane.
• Secondary action  Denaturation of microbial
proteins.
• More active against gram-positive bacteria.
• Present in SAVLON
• Extensively used for surgical scrub, neonatal bath,
mouthwash, obstetrics and as general skin antiseptic

36. • Most widely employed antiseptic in dentistry.
• As 0.12–0.2% oral rinse or 0.5–1% toothpaste, it is
highly active in preventing/treating gingivitis and
plaques
• Good results have been obtained in acute necrotizing
gingivitis
• Rinsing before the procedure, prev. inf. foll.
periodontal & other forms of oral surgery

37. • Twice daily chlorhexidine oral rinse markedly reduces
oral infections in immunocompromised patients,
including AIDS.
• However, it may leave an unpleasant after taste, and
repeated application causes brownish discolouration
of teeth and oral ulceration

38. Quaternary ammonium (Cationic)
antiseptics
1. Cetrimide
2. Cetylpyridinium chloride
3. Benzalkonium chloride

39. • Detergents; cidal to bacteria, fungi & viruses.
• However, many gram-negative bacteria (esp.
Pseudomonas), M. tuberculosis and bacterial spores
are relatively resistant.
• Alter permeability of cell membranes and denature
bact. proteins
• Soaps, being anionic, neutralize their action, while
alcohol potentiates

40. • Spread through oil and grease, have cleansing and
emulgent properties
• Nonirritating and mildly keratolytic
• Germicidal action is rather slow and bacteria may
thrive under a film formed by them on the skin.

41. • Pus, debris and porous material like cotton,
polyethylene reduce their activity.
• Occasionally sensitization occurs
• Widely used as sanitizers, antiseptic and disinfectant
for surgical instruments, gloves, etc, but should not
be considered sterilizing.

42. Cetrimide
• A soapy powder with a faint fishy odour.
• Used as 1–3% solution, it has good cleansing action,
efficiently removing dirt, grease, tar and congealed
blood from road side accident wounds.
• Alone or in combination with chlorhexidine, it is one
of the most popular hospital antiseptic and
disinfectant for surgical instruments, utensils, baths,
etc.

43. Cetylpyridinium chloride
• Similar to Cetrimide
• Incl. in mouth washes & lozenges to ↓ plaque formn.
• Leaves a bad taste & can cause oral ulceration

44. Benzalkonium chloride
• It is highly soluble in water and alcohol.
• A 1:1000 solution is used for sterile storage of
instruments and 1 in 5000 to 1 in 10,000 for
douches, irrigation, etc.

45. Soaps
• Anionic detergents; weak antiseptics, affect only
gram-positive bacteria.
• Their usefulness primarily resides in their cleansing
action.
• Washing with soap and warm water is one of the
most effective methods of preventing transmission
of infection by removing/diluting pathogenic
bacteria.
• Soaps can be medicated by other antiseptics.

46. Ethanol
• It is an effective antiseptic and cleansing agent at 40–
90% concentration.
• The rapidity of action increases with concentration
upto 70% and decreases above 90%.
• Acts by precipitating bacterial proteins.
• A cotton swab soaked in 70% ethanol rubbed on the
skin kills 90% bacteria in 2 min.; has been used
before hypodermic injection and on minor cuts.

47. • Irritant; not be applied to mucous membranes or to
delicate skin (scrotum), ulcers, etc.
• On open wounds it produces a burning sensation,
injures the surface and forms a coagulum under
which bacteria could grow.
• It is a poor disinfectant for instruments—does not kill
spores and promotes rusting
• Usefulness is limited in dentistry
• Eff. conc. cannot be applied on gums, oral mucosa

48. • Conc. present in mouth rinses (5-10%) has no
antiseptic efficacy
• Low conc. enh. the antiseptic activity of iodine and
chlorhexidine when used as solvent for these
• Used to sanitize working surfaces in dentistry but a
poor disnf. for instruments – does not kill spores &
promotes rusting
• Isopropanol  Less volatile; can be used in place of
ethanol

49. Formaldehyde
• Pungent gas—sometimes used for fumigation.
• A 37% aqueous solution called Formalin is diluted to
4% and used for hardening and preserving dead
tissues.
• It denatures proteins and is a general protoplasmic
poison, but acts slowly.
• A broad-spectrum germicide, but use as antiseptic is
restricted by its irritating nature and pungent odor

50. • Though the desens. acn. is weak, low conc. are incl.
in some desens. toothpastes
• It is occasionally employed to disinfect instruments
and excreta.
• Also used to precipitate toxoids from toxins
• Ppl handling formalin can develop eczematoid
reactions

51. Glutaraldehyde
• Less volatile, less pungent, less irritating and better
sterilizing agent than formalin.
• Broad-spectrum activity against bacteria, fungi and
viruses, but needs to be activated by alkalinization of
the solution.
• Organic matter does not inactivate it
• A 2% solution is used to disinfect surg. instruments
and endoscopes, but prolonged contact is needed

52. • Should not be used to disinf. working surfaces
because repeated inh. of its vapours can induce
asthma
• Repeated application on skin can cause sensitization.
• The alkalinized solution has a short shelf life (2
weeks) unless stablilizing agents are added.

53. Boric acid
• Bacteriostatic and a very weak antiseptic.
• Nonirritating; used for irrigating eyes, mouthwash,
douche, etc.
• Boroglycerine paint (30%) is used for stomatitis and
glossitis.
• A 10% ointment (BOROCIDE) is available for cuts and
abrasion.

54. • Included in prickly heat powders and ear drops.
• Systemic absorption causes vomiting, abdominal
pain, diarrhoea, visual disturbances and kidney
damage

55. Silver nitrate
• Rapidly kills microbes, action persisting for long
periods because of slow release of Ag+ ions from
silver proteinate formed by interaction with tissue
proteins.
• Tissues get stained black due to deposition of
reduced silver.
• Uses  Hypertrophied tonsillitis & aphthous ulcers
• Highly active against gonococci—1% solution is used
for ophthalmia neonatorum.

56. Ophthalmia neonatorum

57. Silver sulfadiazine
• Highly active against Pseudomonas and has been
used on burns.

58. Zinc salts
• Astringent and mild antiseptics.
1. Zinc sulfate  Used for eyewash and in eye/ear
drops. Applied to skin, it decreases perspiration.
2. Calamine and zinc oxide  Mildly antiseptic ;
dermal protectives and adsorbants.

59. Gentian violet (crystal violet)
• Active against staphylococci, other grampositive
bacteria and fungi, but gram-negative organisms and
mycobacteria are insensitive.
• Aqueous or alcoholic solution (0.5–1%) is used on
furunculosis, bedsores, chronic ulcers, infected
eczema, thrush, Vincent’s angina, ringworm, etc.
• It has become unpopular due to deep staining

60. T
H
R
U
S
H

62. Acriflavine and Proflavine
• Active against gram-positive bacteria and gonococci.
• Efficacy is not reduced by organic matter and is
enhanced in alkaline medium.
• Solutions lose efficacy on exposure to light—store in
amber bottles.
• Nonirritant and do not retard healing—particularly
suitable for chronic ulcers and wounds.
• Bandage impregnated with acriflavine-vaseline is
used for burn dressing

63. • The triple dye lotion contains gentian violet 0.25% +
brilliant green 0.25% + acriflavine 0.1% (TRIPLE DY),
has been used for burns and for dressing umbilical
stump in neonates.

64. Nitrofurazone (Nitrofural)
• Cidal to both gram-positive and negative, aerobic
and anaerobic bacteria, even in high dilutions, but
activity is reduced in the presence of serum.
• Acts by inhibiting enzymes necessary for
carbohydrate metabolism in bacteria.
• Highly efficacious in burns and for skin grafting.
• Local toxicity is negligible—but sensitization occurs
frequently.

65. Use & sel. Of A/D in dentistry
Purposes Pref. agents
Cleaning & disinf. of working
surfaces, instrument trays,
oper. light handles
Alc., Ammon. antispetics
Cold steriliz. Of certain
instruments & storage of
steriliz. equipment
Glutarald., Ammon.
antispetics
Decontamination of the
dentist’s & assistant’s hands
Soaps, alc, Chloroxylenol,
Ammon. antispetics
Prev. & t/t of dental plaque
& periodontal disease
Chlorhexidine, Ammon.
Antispetics, Triclosan

66. Purposes Pref. agents
T/t of ANUG, aphthous
ulcers & other inf. oral
conditions
Povidone iodine,
Chlorhexidine, H2O2,
Boric acid, silver nitrate
RCT Sod. hypochlorite
Preop. prep. of oral
mucosa by ↓ bact. load
so as to minimise local as
well as distant inf.
Povidone iodine,
Chlorhexidine
As an ingredient of
certain dentrifices
Chlorhexidine, Triclosan,
Amm. antiseptic

67. Locally acting drugs
• Variety of drugs topically applied to the skin or
mucous memb.  Produce therap. eff. localized to
the site of application
• Act by virtue of their physical / mechanical /
chemical / biological attributes

68. Demulcents
• Inert subst. which sooth inflamed/denuded mucosa
or skin by preventing contact with air/irritants in surr
• HMW subst. applied as thick colloidal / viscid soln. in
water
1. Glycyrrhiza
2. Glycerine
3. Methylcellulose
4. Gum acacia
5. Propylene glycol

69. • Glycyrrhiza  Sweet tasting root of liquorice used to
sooth throat & as flavouring / sweetening agent
• Glycerine  Clear, sweet, viscous liquid used as
vehicle for gum/throat paints & as emollient on
dry/cracked lips
• Undil. glycerine is dehyd. & prod. a warm sens. in
mouth. Also, has mild antispetic prop.

70. Emollients
• Bland oily substances which sooth & soften skin
• Form an occlusive film over the skin prev. evapor.
• Used as vehicle for topically applied medicaments &
as ointment bases
1. Olive oil
2. Sesame oil
3. Liquid paraffin
4. Hard & soft paraffin
5. Bees wax

71. Adsorbants & protectives
• Adsorbants  Finely powdered, inert & insoluble
solids capable of binding to their surface (adsorbing)
noxious & irritant substances
• Also called protectives because they afford physical
protection to the skin or mucosa
• Other protect. form a continuous, adherent &
flexible occlusive coating on the skin
• Demulcents & emollients also serve as protectives

72. • Mg stearate, Zn stearate, talc, calamine, ZnO, starch,
aloe vera gel, dimethicone & sucralfate are used as
protectives
• Sucralfate is an Aluminium salt of sulfated sucrose
used as PU protective
• Topical gel of Sucralfate applied on aphthous ulcers,
burns, bedsores, excoriated skin, diabetic ulcers

73. Astringents
• Subst. that ppt. proteins but do not penetrate cells
(affect the superficial layer only)
• Toughen the surface making it mech. stronger &
decrease exudation
1. Tannic acid
2. Zn chloride
3. ZnSO4
4. AlCl3
5. Ferric chloride

74. • Incl. in several mouthwashes & dental gels to afford
symptomatic relief & promote healing of oral lesions
as well as to ↓ dentine sensit. & gum bleeding
• Alc. unsuitable for use in mouth (burning sens.);
rubbed on skin to prev. bedsores
• Other uses
1. Bleeding piles
2. Antiperspirant / deodorant

75. Caustics
• Corrosive chem. causing local tissue destr. &
sloughing
• Conc. solns. of AgNO3, ZnCl2, Phenol, Trichloroacetic
acid & Podophyllum resin are used to remove moles,
warts, papillomas & necrotic material (To be applied
carefully on the lesions only)

76. • Use is limited in dentistry
1. Occasional applic. on aphthous ulcers
2. AgNO3 painted on exposed necks of teeth can
reduce dentine sensitivity (not favoured due to
black staining)
3. Carefully applied trichloroacetic acid can reduce
pain of pericoronitis