Antiseptics are the drugs which are used to prevent sepsis by preventing or inhibiting the growth of microorganisms. These are used in/on the body.

1. ANTISEPTICS & DISINFECTANTS
Presented By:
Mr. Abhay Rajpoot

2. INTRODUCTION
Antiseptics are the drugs which are used to prevent sepsis by preventing or
inhibiting the growth of microorganisms. These are used in/on the body.
 Disinfectants are the drugs that prevent infection by killing bacteria's.
These are used on equipment or surfaces and not on/ in the body, e.g.
phenol.
 Germicides is the common term used for both disinfectants and
antiseptics. e.g. Dettol, sevlon
 Sterilization is the process of killing pathogenic as well as non-pathogenic
microorganism along with their spores.

3. MECHANISM OF ACTION
Germicides may act by the following mechanisms:
 Oxidation of bacterial protoplasm.
 Denaturation of bacterial proteins including enzymes.
 Detergent like action increasing permeability of bacterial hormone.
 Competition with essential substrates for the important enzymes in the
bacterial cell.
A ideal germicide should have a wide antibacterial spectrum, should be
chemically stable, should have rapid action, non-irritant to the tissues, not
interfere with wound healing activity even in presence of pus, exudates and
tissue degradation products; it should not be absorbed into systemic
circulation.

4. FACTORS THAT INFLUENCE THE ACTIVITY OF GERMICIDAL AGENTS
 Concentration of the drug and duration of contact: In general,
higher the concentration of the antiseptic, greater in its effect. But
alcohol is an exception to this and at 70% concentration maximum
antiseptic effect is seen.
 Susceptibility of the organisms: Spores and viruses are resistant to
many antiseptics.
 Temperature: Rise in temperature will increase antiseptic activity.

6. ALCOHOLS
These act by denaturing proteins of microbes. e.g. Ethyl alcohol, Isopropyl
alcohol and Methyl alcohol, etc.
Advantages
 Alcohols are used as common antiseptics or precipitating bacteria
proteins.
 These are most effective against bacteria
 Isopropyl alcohol is preferred as fat solvent, bactericidal and less volatile.
 Ethyl alcohol is used to clean the skin before infections and surgeries;
prevention and treatment of bed sores.
 Isopropyl alcohol is used for disinfection of thermometers and sterilization
of skin and catgut
 Methyl alcohol is used for treating cabinets and incubators against fungal
spores.

7. Disadvantage
 It has poor activity against spores. some viruses and fungi.
 Irritant: Causes burning sensation when applied on open wounds.
 Alcohols are flammable. should be allowed to evaporate before using cautery
or laser surgery.

8. HALOGENS
Iodine
It is one of the oldest antiseptics. It has a broad spectrum of activity. It is a
powerful bactericidal, sporicidal, fungicidal and viricidal agent. The
activity is inhibited by organic material but enhanced by alcohol. Higher
concentration and longer duration is required. It kills amoeba.
The disadvantages of halogen are:
Iodides have no antibacterial action. It is irritating and painful. It delays
healing. It stains skin, Rashes, Fever and generalized skin eruptions may
develop in some patients who are sensitive to iodine. Prolonged systemic
use cause iodism.

9. Uses
 Tincture iodine (2% in alcohol) is used for cleaning unbraided skin before
surgery.
 Ointments are applied for treating ringworm.
 For purification of non-drinking water: 5 drops of iodine solution are added
to a litre of water. It is allowed to react for 15 minutes.
 Mandel's Paint (Compound Iodine Paint) is used in the treatment of
tonsillitis and pharyngitis.

10. POVIDONE-IODINE (BETADINE)
It is used for disinfection of skin before surgery. It is available as solution,
e.g. ointment and gel. If external use preparation is taken orally
accidentally causes severe irritation of gastric mucosa and may lead to
coma and death. Antidote available is 5% sodium thiosulfate.

11. PHENOL DERIVATIVES
Phenol (carbolic acid) is one of the oldest antiseptics introduced by Lord
Lister in 1867. it is bactericidal and fungicidal but has poor action against
spores and viruses. It acts by denaturing the bacterial protein. It also has a
mild local anaesthetic action. Phenol rapidly penetrates even on intact skin
and mucous membrane. It is a protoplasmic poison. Phenol is extremely
irritant to exposed tissues (corrosive), when swallowed. It burns buccal,
oesophageal and gastric mucous membranes

12. Carbolic Acid
Have local anaesthetic effect along with antiseptic effect. Highly effective against
bacteria and fungi.
Uses
 Used to disinfect urine, feces and sputum of patients.
 Used along with camphor for relieving exposed tooth pulp ache.
 Used on dog bite and snake bite areas.
 Calamine containing carbolic acid is used to treat insect bites; chickenpox
eruptions and similar diseases.
 To relieve earache and ear itching, it is used as ear drops along with glycerine.
Disadvantages
 Highly irritant and may cause tissue necrosis.
 Effect is reduced in organic matter presence and also in combination with
glycerine or alcohol.
 Not effective against spores and viruses.

13. ALDEHYDES
Glutaraldehyde
It is a dialdehyde used as a 2% solution. It is less volatile, less pungent, less
irritating.
Uses
 It is a bactericidal, sporicidal, fungicidal and viricidal.
 Its pH should be between 7.4 and 8.5. it is less irritant than formaldehyde
and has greater sporicidal activity.
 It does not damage lenses and cementing material in endoscopes.
 Glutaraldehyde is superior to formaldehyde for sterilizing rubber. plastic and
meta] appliances
 2% solution is used for local application in idiopathic hyperhidrosis of palms
and soles.

14. Formaldehyde (40% Formalin)
Aldehydes is acted by alkylation of chemical groups in proteins and nucleic acids.
 Formaldehyde is a gas at room temperature used for fumigation.
 The 37% aqueous solution is non-corrosive and has a broad antimicrobial spectrum.
 It has a pungent odor and is highly imitating to respiratory mucous membranes and eyes.
 Formaldehyde is also a carcinogen and Occupational Safety and Health Administration
(OSHA) has set standards to limit exposure of health care workers to formaldehyde.
.

15. Uses
 Formaldehyde gas is used for fumigation and for sterilizing
instruments which cannot be moistened with solution: Formaldehyde
40% solution ( 100% formalin) in water is used for disinfection of
surgical instruments and gloves. embalming and preservation of
tissues.
 Fibre optics endoscopies. respiratory therapy equipment,
hemodialyzers and dental hand pieces which cannot withstand high
temperatures of steam sterilization are disinfected with
formaldehyde.
 It is used for dressing of root canals.
 Effective against mycobacterium tuberculosis. This makes it useful for
sterilization of sputum and excreta of tuberculous patients

16.  Disadvantages
 Solution of this drug is extremely irritant.
 On ingestion of formaldehyde acute poisoning is produced characterized by
abdominal pain, vomiting, diarrhea and renal failure. It is treated symptomatically.

17. DISINFECTANTS/SURFACTANTS
Disinfectants/Surfactants are chemicals that lower the surface tension of
solution and are termed as detergents. They may be anionic, cationic,
ampholytic surfactants or polysorbates.
Anionic Surfactants
They dissociate in aqueous solutions to form a large and complex anion which
lowers the surface tension, e.g. soaps. Effective for gram positive and acid fast
organisms. Microorganisms are enmeshed in the lather and washed away on
rinsing. Anionic surfactants have a narrow spectrum; precipitate in hard water;
cause drying of the skin.

18. Cationic Surfactants
e.g. Benzalkonium chloride, cetrimide, cetylpyridinium chloride,
dequalinium chloride. Cationic surfactants dissociate into the large
cations. These are:
 Active against gram +ve and gram -ve organisms (less active against
spores, viruses and fungi).
 Most effective in neutral solution.
 Non-irritating and safe.
 Incompatible with anionic surfactants.
 Absorbed by cotton and rubber.
 One of the most commonly used germicidal agents.

19. Benzalkonium chloride (Zephiran) has an aromatic odour and is soluble in
water.
 1:1000 solution for cleansing skin.
 1:2000 for mucous membranes and denuded skin.
 1:20.000 for irrigation of the bladder and urethra.
 It is also used for (1:1000-4000) storing sterilized surgical instruments.
But instruments should be thoroughly washed before use.

20. Thank You