Povidone-iodine

Systematic (IUPAC) name
2-Pyrrolidinone, 1-ethenyl-, homopolymer, compd. with iodine.
Identifiers
CAS number	25655-41-8
ATC code	D08AG02 D09AA09 D11AC06 G01AX11 R02AA15 S01AX18 QG51AD01
PubChem	410087
Chemical data
Formula	(C6H9NO)n·xI
Mol. mass	variable
Pharmacokinetic data
Bioavailability	?
Metabolism	?
Half life	?
Excretion	?
Therapeutic considerations
Pregnancy cat.	?
Legal status
Routes	topical|-	Y(what is this?)  (verify)

Povidone-iodine (PVP-I) 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 at the Industrial Toxicology Laboratories in Philadelphia by H. A. Shelanski and M. V. Shelanski^[2]. They carried out invitro tests to demonstrate antibacterial activity, and found that the complex was less toxic than tincture of iodine in mice. Human clinical trials showed the product to be superior to other iodine formulations.^[3]

It was first sold in 1955, and has since become the universally preferred iodine disinfectant. ^[3]

[edit] Properties

PVP-I is completely soluble in cold 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 povoiodine-iodine (PVPI) 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.

[edit] Uses

Wound area covered in povidone-iodine. Gauze has also been applied.

Povidone-iodine applied to an abrasion using a cotton swab.

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 povidone-iodine, 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^[4], and the sensitization rate to the product is only 0.7%^[5] 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.

[edit] Nanotechnology

Recently povidone-iodine has been incorporated into the field of nanotechnology. A wound-healing application has been developed which employs a mat of single wall carbon nanotubes (SWNTs) coated in a monolayer of povidone-iodine^[6]. It has been previously shown that the polymer polyvinylpyrrolidone (PVP, povidone) can coil around individual carbon nanotubes to make them water-soluble^[7]. This povidone-iodine coated carbon nanotube mat serves an electrically conductive bandage with antiseptics properties. Traditionally povidone-iodine is soaked into absorbant materials for application to wound sites, but this can lead to contact burns if excessive amounts of povidone-iodine are used. Additionally, traditional methods can allow large quantities of povidone-iodine to be released from the bandage material upon contact with fluids at the wound site. Meanwhile, the carbon nanotube supported povidone-iodine is prevented from escaping from the bandage in large amounts, and after an initial release of excess povidone-iodine to the wound site, a secondary slow release of iodine from the carbon nanotube bound povidone takes place.

Schematic of povidone-iodine complex wrapping a single wall carbon nanotube (black).^[6]

[edit] See also

• Tincture of iodine
• Lugol's iodine
• Betadine
• Iodophor

[edit] References