Povidone Iodine -Revisited
Povidone Iodine -Revisited
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Povidone Iodine or polyvinyl pyrrolidone-iodine, commonly abbreviated as PVP-I was discovered by American scientists H. A. Shelanski and M. V. Shelanski. PVP- I was introduced to the pharmaceutical market as an antiseptic agent in the 1950’s and is found to be more effective than other iodine formulations and was less toxic
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10.5866/3.3.617
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INDIAN JOURNAL OF DENTAL ADVANCEMENTS
J o u r n a l h o m e p a g e : w w w. n a c d . i n
REVIEW
Povidone Iodine -Revisited
Sunil Kumar P1, Raja Babu P2, Jagadish Reddy G3, Uttam A4
doi:10.5866/3.3.617
Department of Periodontics
Kamineni Institute of Dental Sciences
Narketpally, Nalgonda Dist. A.P.
Sr Lecturer1
Professor & HOD2
Senior Lecturer3
PG Student4
Article Info
Received: April 15, 2011
Review Completed: May, 17, 2011
Accepted: June, 19, 2011
Available Online: October, 2011
© NAD, 2011 - All rights reserved
ABSTRACT:
Povidone Iodine or polyvinyl pyrrolidone-iodine is an iodophor
and a broad spectrum antimicrobial agent delivered in many forms
including powders, gels, lotions, ointments, sprays and mousses.
Compared to other similar compounds Povidone iodine is highly
soluble and less toxic making it widely suitable for surgical asepsis
and wound dressing. In dentistry it is used for pre surgical skin
preparation, pre procedural rinse to reduce bacteremia and
microbial load in aerosols, root canal irrigant and intracanal
medicament.
Key words: Povidone Iodine, Iodophor, Asepsis, Disinfection
Povidone Iodine -Revisited
Introduction:
Povidone Iodine or polyvinyl pyrrolidone-iodine,
commonly abbreviated as PVP-I was discovered by
American scientists H. A. Shelanski and M. V. Shelanski. PVPI was introduced to the pharmaceutical market as an
antiseptic agent in the 1950’s and is found to be more
effective than other iodine formulations and was less toxic.
Structure:
PVP-I is 2-Pyrrolidinone, 1-ethenyl-,
photopolymer, compound with iodine1
CHEMICAL STRUCTURE
Properties:
PVP iodine is a loose complex of elemental
iodine with a neutral, amphipathic organic
Email for correspondence:
drpsunilkumar@gmail.com
compound, poly vinyl pyrrolidone, which serves as a
sustained release reservoir of iodine. PVP-I is a broad
spectrum biocidal agent which is highly soluble than
other iodine compounds like Tincture of iodine and
Lugols solution. PVP-Iodine is also soluble in: ethyl
alcohol, isopropyl alcohol, glycols, glycerin, acetone
and polyethylene glycol.2 Povidone iodine is highly
stable when stored away from moisture and light.
PVP-I is effective in the range of pH 3 -6 and average
particle size ranges from 90 to 140μ.
Bio-Compatibility:
PVP-I differs from iodine, in that it is less irritating
to the skin and does not require iodides or alcohol
to dissolve. Additionally, PVP-I stains are waterwashable. Compared to other preparations, PVPiodine exhibits markedly lower oral toxicity.
Consequently, the accidental ingestion of PVP iodine
solution is much less hazardous that from equal
amounts of available iodine solutions. For this reason,
PVP-iodine solutions do not require the hazardous,
poisonous warning labels on bottle that iodine
products must have. PVP-I is delivered in many forms
including powders, gels, lotions, ointments, sprays
and mousses. However the efficacy of action is
dependent on available free iodine.
IJDA, 3(3), July-September, 2011
617
Povidone Iodine -Revisited
Mode of Action:
In the PVP-Iodine complex, the iodine does not
exist as a single species, and infact several forms of
iodine have been characterized:
•
•
•
•
Available iodine: Contains all the iodine species
which can be titrated with sodium thiosulfate
Iodide: Negatively charged ion; necessary for the
complexation of iodine
Total iodine: Given by the sum of available
iodine and iodide.
Free Iodine: The type of iodine which can be
extracted from aqueous PVP-Iodine solution.
The disinfecting characteristics of iodine arise
from its ability to substitute for covalently bound
hydrogens in compounds containing -OH, -NH, -SH,
or CH functional groups. PVP-I being a polymeric
iodophor, reacts with oxygen containing functional
groups. The difference between a conventional
iodine solution and an iodophor is that the latter
carries practically all the iodine in a complexed form,
so that the concentration of the free iodine in the
solution is always very low. This property has the
effect of reducing the drawbacks associated with the
presence of elemental iodine i.e. high toxicity, high
level of irritation and staining power. 3
Biocidal action:
PVP-Iodine is used in both human and veterinary
medicine to kill on contact a wide variety of bacteria,
viruses, fungi, protozoa and yeasts. The determining
factor of the bactericidal action of PVP-I remains the
concentration of free iodine. 3 In pharmaceutical
formulations that contain both iodine and iodide, the
bactericidal effect can almost entirely be attributed
to free molecular iodine.3
The microbiocidal action of PVP-Iodine, as
discussed earlier, is related to the non-complexed,
freely mobile elemental iodine, I2, the active form of
which is polarized by water and hence can be
considered to be H2OI+ in its final state. This activated
iodine reacts in electrophilic reactions with enzymes
of the respiratory chain as well as with amino acids
from the cell membrane proteins both located in the
cell wall. As a result, the well-balanced tertiary
structure necessary for maintaining the respiratory
chain is destroyed and the microorganism
irreversibly damaged. Consequently, PVP-Iodine has
a nonspecific mode of action.
PVP-I at concentrations more than 0.5% has shown
618 IJDA, 3(3), July-September, 2011
Sunil Kumar, et, al.
to be rapidly virucidal. Studies have shown that PVP-I
0.25% surgical scrub and solution inactivated HIV
within seconds in-vitro, and if used in clinically
achievable concentrations could serve as a surface
disinfectant in hospital settings where HIV may be
present. PVP-I was the most effective when compared
with benzalkonium chloride and chlorhexidine
digluconate, since it also yielded negative results in the
HIV-specific plaque forming assay.4
Table: 1 Efficacy of PVP-I against different
micro-organisms5
Organisms
Staphylococcus
Pseudomonas
Streptococcus
Escherichia
Salmonells
Candida
Enterobacter
Klebsiella
Clostridium
Corynebacterium
Mycobacterium
PVP-I
Contact
(available iodine kill time in
range in ppm)
seconds
66-2500
25-2500
200-2500
200-2500
1000-2500
3.75-2500
1000-2500
500-2500
1000
2500
2500
15-180
15-80
15-30
30-120
15-60
10-120
60
60
30-60
60
60-120
Uses of Povidone Iodine:
i.
As Skin Disinfectant: The patient’s skin is a
major source of pathogens that cause infection.
Traditional aqueous-based iodophors, such as
povidone-iodine, are one of the few products
that can be safely used on mucous membrane
surfaces.6 PVP-I as 10% solution(1% available
iodine) is widely used for skin disinfection and
7.5% PVP-Iodine solution (0.75% available
iodine) is used for wound cleansing. The resultant
broad spectrum of antimicrobial activity is well
documented and its efficacy, particularly in
relation to resistant micro-organisms such as
methicillin-resistant Staphylococcus aureus, has
been shown.7
ii. Pre Operative skin preparation: Procedural
and surgical site infections create difficult and
complex clinical scenarios. A source for
pathogens is often thought to be the skin
surface, making skin preparation at the time of
Povidone Iodine -Revisited
Sunil Kumar, et, al.
the procedure critical. The most common skin preparation agents used today include products containing
iodophors. PVP-Iodine products have been widely used for pre-operative skin preparation and in various
surgical procedures and shown to significantly lower subsequent infection rates.8 In the aqueous form,
most commercially available iodophors require a 2-step application in a scrub-and-paint technique, and
their activity is limited by the amount of time the agent is in contact with the skin.9
iii. Topical Application: PVP-I in the form of ointments, sprays, lotions is used to prevent microbial
contamination of wounds, ulcers, burns etc. PVP-Iodine effectively controls bacterial growth and protects
the developing epithelium. Unlike many antibiotic agents it has the added advantage in that its continued
use does not result in the generation of resistant organisms.10
Table 2: The topical application of different PVP-I preparations and their uses:
Application
PVP-I Preparation
Pre and post-operative antiseptic skin cleanser for major
and minor surgical procedures.
Topical Solution 10% w/v
Topical Alcoholic Solution 10% w/v
Where quick drying effect is required
Liquid Soap 4% w/v
Skin cleanser for treatment of acne vulgaris,
General disinfection of the skin.
Quick drying antiseptic for the treatment and prevention
of infection. Useful against herpes simplex, herpes zoster,
grazes, abrasions, cuts and wounds.
Treatment and prevention of infection in minor cutsand
abrasions, minor surgical procedures and small areas of burns.
Treatment of infections in decubitus and stasis ulcers.
Antiseptic skin cleansers for pre-operative
scrubbingand washing by surgeons and theatre staff
and preoperative preparation of patients’ skin.
Antiseptic Paint 10% w/v
Ointment 10%w/v
Dry Powder Spray 2.5% w/v
Ointment 10%w/v Dry Powder Spray 2.5% w/v
Surgical Scrub 7.5% w/v
with non-ionic surfactants
Oro-Dental Uses:
i. Anti-Caries Action: For prevention of dental caries, S. mutans numbers must be reduced and prevented
from returning to the original level. An antibacterial agent that is effective and also acceptable to young children
can help to establish a favorable oral environment and halt the caries process. In children suffering from early
childhood caries, 10% povidone iodine applied in 3 month intervals over a period of one year has resulted in
significant reduction in the rise of Streptococcus mutans levels decreasing the oral load of the organisms.
Reduction in counts; in turn decreased the relapse of caries in these children.11,12
ii. Pre-procedural Rinse: Antimicrobial mouth rinses used by patients before a dental procedure are intended
to reduce the number of microorganisms released by a patient in the form of aerosols or spatter that subsequently
can contaminate equipment, operatory surfaces, and dental health care personnel. Pre-procedural rinse with
povidone iodine can reduce the level of oral microorganisms generated in aerosols or spatter during routine
dental procedures with rotary instruments (e.g., dental handpieces, ultrasonic scalers).13 Antimicrobial mouth rinses
used by the patient before a dental procedure can decrease the number of microorganisms introduced into the
patient’s bloodstream during invasive dental procedures. The scientific evidence is not clear concerning the
incidence and nature of bacteremia from invasive dental procedures, the relationship of bacteremia to disease,
and the preventive benefit of antimicrobial rinses. However, the American Heart Association suggests that patients
at risk for bacterial endocarditis use an antimicrobial mouth rinse before dental treatment.14
iii. Anti-plaque action: Povidone iodine appears to have no significant plaque inhibitory activity when used as
1% mouthwash and 30 to 40 % overall reduction in aerobes and anaerobes occurred with the active preparation
which was significant.15 The absorption of significant levels of iodine through the oral mucosa may make this
compound unsatisfactory for prolonged use in the oral cavity. Also, it could cause a problem of iodine sensitivity
in sensitised individuals. This property combined with reversible staining and unpalatable taste made PVP-I
disadvantageous when compared to Chlorheidine and essential oil mouth washes.
IJDA, 3(3), July-September, 2011
619
Povidone Iodine -Revisited
iv. Endodontics: The essential role of
microorganisms in the development and
perpetuation of pulp and periapical diseases has
clearly been demonstrated in animal models and
human studies. Application of PVP-I solution as
an endodontic irrigant was proposed based on
its rapid antiseptic action against a broad range
of
microorganisms,
low
toxicity,
hypoallergenicity, and greatly reduced tendency
to stain dentin than other iodine containing
antiseptics.16 10% PVP-I is often employed for
tooth surface disinfection and operating field
which includes tooth, rubberdam and clamp.
Fungi may be involved in cases of persistent and
secondary infections associated with recalcitrant
periradicular lesions; therefore the spectrum of
antimicrobial activity of endodontic
medicaments and irrigants should include these
organisms. 2% PVP-I 4% killed all C albicans cells
within 30 seconds, and a 10-fold dilution showed
complete killing within 5 minutes.
Effect on fibroblasts: The fibroblast is the
predominant cell type in the soft connective tissues
of the periodontium and consequently plays a central
role in normal function and in pathologic alterations.
PVP-I has shown dose dependant reduction in
cellular proliferation of fibroblasts. It was also seen
that at dilute concentrations Povidone-Iodine
showed insignificant effect on fibroblasts.17
Comparision with Chlorhexidine: Numerous
studies exist in the literature comparing PVP-I with
Chlorhexidine. In surgical site asepsis, PVP-I was found
to be more effective in controlling the infection.
However Chlorhexidine-alcohol was significantly
more protective than povidone-iodine against both
superficial incisional infections and deep incisional
infections but not against organ-space infections. 18
PVP-I lacks the persistent action of chlorhexidine but
is less toxic and can be safely used in areas with ulcers
and burns. PVP-I has broader microbicidal property
especially on resistant bacteria like M tuberculosis
and other spore forming bacteria. Protein-rich
biomaterial and other organic materials can
neutralize the germicidal activity of povidone-iodine,
where as they have little effect on the antibacterial
activity of chlorhexidine.
Conclusion: Since its discovery Povidone Iodine
remains a commonly used disinfectant, and has been
widely used in its different forms. The highly soluble
nature, low toxicity, widest bactericidal range has
made it a trusted agent in maintaining asepsis. The
620 IJDA, 3(3), July-September, 2011
Sunil Kumar, et, al.
recent emergence of single wall carbon nanotubes
coated in a monolayer of povidone-iodine and its
effect on wound healing holds a promising future for
this compound.
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