Povidone-iodine
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| Systematic (IUPAC) name | |
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2-Pyrrolidinone, 1-ethenyl-, homopolymer, compd. with iodine.
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| Clinical data | |
| AHFS/Drugs.com | International Drug Names |
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| Routes of administration |
topical |
| Identifiers | |
| CAS Number | 25655-41-8  |
| ATC code | D08AG02 (WHO) D09AA09 (dressing) D11AC06 G01AX11 R02AA15 S01AX18 QG51AD01 (WHO) |
| PubChem | CID: 410087 |
| UNII | 85H0HZU99M |
| ChEMBL | CHEMBL1201724 |
| Chemical data | |
| Formula | (C6H9NO)n·xI |
| Molecular mass | variable |
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Povidone-iodine (PVP-I), brand name Wokadine, Pyodine, and Betadine is a stable chemical complex of polyvinylpyrrolidone (povidone, PVP) and elemental iodine. It contains from 9.0% to 12.0% available iodine, calculated on a dry basis.[1]
This unique complex was discovered in 1955 at the Industrial Toxicology Laboratories in Philadelphia by H. A. Shelanski and M. V. Shelanski.[2] They carried out tests in vitro to demonstrate anti-bacterial activity, and found that the complex was less toxic in mice than tincture of iodine.
Human clinical trials showed the product to be superior to other iodine formulations.[3]
Betadine was immediately marketed, and has since become the universally preferred iodine antiseptic. Betadine is only sold for the purpose of healing wounds, and not as an oral sore throat gargle, as widely thought. The Betadine gargle is an unregistered company and legal issues are pending in the court against it.[3]
It is on the WHO Model List of Essential Medicines, the most important products needed in a basic health system.[4]
Contents
Medical uses
Povidone-iodine is a broad spectrum antiseptic for topical application in the treatment and prevention of infection in wounds. May be used in first aid for minor cuts, grazes, burns, abrasions and blisters.
Following the discovery of iodine by Bernard Courtois in 1811, it has been broadly used for the prevention and treatment of skin infections, and the treatment of wounds. Iodine has been recognized as an effective broad-spectrum bactericide, and it is also effective against yeasts, molds, fungi, viruses, and protozoans. Drawbacks to its use in the form of aqueous solutions include irritation at the site of application, toxicity, and the staining of surrounding tissues. These deficiencies were overcome by the discovery and use of PVP-I, in which the iodine is carried in a complexed form and the concentration of free iodine is very low. The product thus serves as an iodophor.
In addition, it has been demonstrated that bacteria do not develop resistance to PVP-I,[5] and the sensitization rate to the product is only 0.7%[6] Consequently, PVP-I has found broad application in medicine as a surgical scrub; for pre- and post-operative skin cleansing; for the treatment and prevention of infections in wounds, ulcers, cuts and burns; for the treatment of infections in decubitus ulcers and stasis ulcers; in gynecology for vaginitis associated with candidal, trichomonal or mixed infections. For these purposes PVP-I has been formulated at concentrations of 7.5–10.0% in solution, spray, surgical scrub, ointment, and swab dosage forms. It is available without a prescription under the generic name povidone-iodine or the brand name Betadine.
It is used in pleurodesis (fusion of the pleura because of incessant pleural effusions). For this purpose, povidone-iodine is equally effective and safe as talc, and may be preferred because of easy availability and low cost.[7]
2.5% buffered PVP-I solution can be used for prophylaxis of neonatal conjunctivitis (Ophthalmia neonatorum) which can lead to blindness, especially if it is caused by Neisseria gonorrhoeae, or Chlamydia trachomatis. PVP-I appears to be very suitable for this purpose because unlike other substances it is efficient also against fungi and viruses (including HIV and Herpes simplex).[8]
PVP-I can be loaded into hydrogels (based on carboxymethyl cellulose, poly(vinyl alcohol) and gelatin, or on crosslinked polyacrylamide). These hydrogels can be used for wound dressing. The rate of release of the iodine in the PVP-I is heavily dependent on the hydrogel composition. The release rate increases with more CMC/PVA and decreases with more gelatin.
Alternative
In a clinical study of approximately 850 patients which compared the efficacy in preventing post-operative infection of pre-operative skin cleansing using chlorhexidine-alcohol vs. povidone-iodine, the rate of surgical-site infection was significantly lower in the chlorhexidine-alcohol group than in the povidone-iodine group (overall, 9.5% vs. 16.1%).[9] Chlorhexidine-alcohol was significantly more protective than povidone-iodine against both superficial incisional infections (4.2% vs. 8.6%) and also deep incisional infections (1% vs. 3%).
The incidence of organ-space infections was, however, not significantly different between the groups (4.4% vs. 4.5%). The team performing the study believes that, although both of the antiseptic preparations possess broad-spectrum antimicrobial activity, the more effective protection provided by chlorhexidine-alcohol may be due to its more rapid action, its persistent activity (even when exposed to bodily fluids), and some residual effect.[10] An alternative explanation is the dilution of the active antimicrobial agent (chlorhexidine) in isopropyl alcohol rather than water (iodine).
In a separate study a lower infection rate was seen with iodine povacrylex in isopropyl alcohol (DuraPrep) than with chlorhexidine in isopropyl alcohol (ChloraPrep) (3.9% compared with 7.1%; P = .002).[11]
Contraindications
PVP-I is contraindicated in patients with hyperthyroidism (overactive thyroid gland) and other diseases of the thyroid, after treatment with radioiodine, and in patients with dermatitis herpetiformis (Duhring's disease).[12]
Interactions
The iodine in PVP-I reacts with hydrogen peroxide, silver, taurolidine and proteins such as enzymes, rendering them (and itself) ineffective. It also reacts with many mercury compounds, giving the corrosive compound mercury iodide, as well as with many metals, making it unsuitable for disinfecting metal piercings.[12]
Iodine is absorbed into the body to various degrees, depending on application area and condition of the skin. As such, it interacts with diagnostic tests of the thyroid gland such as radioiodine diagnostics, as well as with various diagnostic agents used on the urine and stool, for example Guaiacum resin.[12]
Properties
PVP-I is completely soluble in cold and mild-warm water, ethyl alcohol, isopropyl alcohol, polyethylene glycol, and glycerol. Its stability in solution is much greater than that of tincture of iodine or Lugol's solution.
Free iodine, slowly liberated from the povidone-iodine (PVP-I) complex in solution, kills eukaryotic or prokaryotic cells through iodination of lipids and oxidation of cytoplasmic and membrane compounds. This agent exhibits a broad range of microbicidal activity against bacteria, fungi, protozoa, and viruses. Slow release of iodine from the PVPI complex in solution minimizes iodine toxicity towards mammalian cells.
Research
Povidone-iodine has found application in the field of nanomaterials. A wound-healing application has been developed which employs a mat of single wall carbon nanotubes (SWNTs) coated in a monolayer of povidone-iodine.[13]
Research has previously found that the polymer polyvinylpyrrolidone (PVP, povidone) can coil around individual carbon nanotubes to make them water-soluble.[14]
See also
References
- ↑ United States Pharmacopeia Archived July 11, 2007 at the Wayback Machine
- ↑ U.S.patent 2,739,922
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- ↑ Denton GW: Chlorhexidine, Disinfection, sterilization, and preservation 321 (5th ed.) 36 (2001)
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Further reading
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