Antimicrobials povidone-iodine

Povidone—iodine is a brown, water-soluble powder containing approximately 10% iodine. However, the amount of free iodine, which is responsible for the antimicrobial activity, is low in a concentrated solution, but is released as the solution is diluted (41). Concentrated solutions have actually been contaminated with bacteria (42). For use as an antiseptic, povidine—iodine is diluted with water or alcohol to a concentration of 1% iodine. Detergents are added if it is used as a surgical scmb. lodophors are important as broad-spectmm antiseptics for the skin, although they do not have the persistent action of some other antiseptics. They are also used as disinfectants for clinical thermometers that have been used by tuberculous patients, for surface disinfection of tables, etc, and for clean equipment in hospitals, food plants, and dairies, much as chlorine disinfectants are used. 

Superficial bacterial infections, e.g. impetigo, eczema, are commonly staphylococcal or streptococcal. They are treated by a topical antimicrobial for less than 2 weeks and applied twice daily after removal of crusts that prevent access of the drug, e.g. by a povidone-iodine preparation. Very extensive cases need systemic treatment. 

Three classes of antimycotic antibiotic are available polyenes, azoles and nucleoside analogs. In addition, non-specific antimicrobial agents such as povidone iodine, chlorhexidine and silver sulfadiazine can be adapted for ophthalmic use. 

Topical 2% povidone iodine solution and 0.2% chlorhexidine gluconate solution have broad antimicrobial profiles and may be used as cheap spectrum and effective antifungal agents in equine ketomycosis, particularly where Fusarium spp. are involved. A1% dermatological cream formulation of silver sulfadiazine has both antifungal and antibacterial properties and is reasonably well tolerated topically in the horse eye. Its use is advocated where cost restraints exist or for prophylaxis in comeal injuries involving embedded plant material (Hamor Whelan 1999). 

Antimicrobial compounds available in over-the-counter preparations are cetrimide, chlorhexidine, povidone-iodine, triclocarban and triclosan. 

Povidone-iodine is an iodophore in which povidone, a vinyl polymer, acts as a carrier for iodine, allowing its gradual release for antimicrobial and antiseptic effect. It is less potent than preparations containing free iodine but is less toxic. 

R Aly, HI Maibach. Comparative antimicrobial efficacy of a 2 minute surgical scrub with chlorhexidine gluconate, povidone iodine, and chloroxylenol sponge-brushes. Am J Infect Control 16(4) 173-177, 1988. 

Clinical Applications of Povidone-Iodine as a Topical Antimicrobial... 

H Vorheff, UP Vorheff, P Mehta, JA Ulrich, RH Messer. Antimicrobial effect of chlorhexidine and povidone-iodine on vaginal bacteria. J Infect 8 195-199, 1984. 

The sequential use of a chlorhexidine gluconate-containing detergent followed by an alcoholic disinfectant reduced the release of resident skin bacteria significantly better than did a sequence of unmedicated soap and alcohol used for the same periods. Paulson compared five surgical hand-scrub preparations (4% CHG brush, 2% CHG solution, povidone-iodine brush, parachlorometaxylenol brush, and alcohol-impregnated brush) [ 14]. Only the CHG products demonstrated antimicrobial effectiveness in all three parameters (immediate, persistent, and residual). A comparison also was made between a 5-minute povidone-iodine scrub and a 1 -minute povidone-iodine scrub, followed by alcohol foam [15]. The total number... 

Although all methods were initially comparable, with bacterial reductions of greater than 99%, recolonization of a test site was significantly reduced after 60 minutes when prepared with an alcohol and iodophor drape, compared with the other methods. Jeng and Severin investigated the performance of a povidone-iodine gel alcohol (5% povidone-iodine and 62% ethanol in gel form) as a 30-second, one-time application preoperative skin preparation [20]. The povidone-iodine gel alcohol formulation delivered rapid and persistent antimicrobial activity against a broad spectrum of bacteria, both in vitro and in vivo, and was found to be an effective skin preparation formulation for use in a single-step 30-second application. 

For the most part, there is considerably less risk of nosocomial infection for these applications because the device is inside the patient s body so briefly. It appears that 70% alcohol alone is adequate for this application. However, other antimicrobials, such as povidone iodine and chlorhexidine gluconate, are also used. 

Figure 3 Test data for two different antimicrobial body wash treatments, povidone iodine (7.5%, PVPI) or a novel alcohol-based formulation (TSPN), followed with a preoperative preparation of like composition painted onto the test subjects immediately following the time = 0 hours sampling. Note that with the PVPl-based treatment regimen, the minimum 3 logio reduction from baseline microbial counts at 0.17 hours (10 min) is not obtained, whereas with the TSPN system the required reduction is obtained at both the 0.17-hour sampling as well as the 6-hour (end of typical surgical procedure) sampling. The average baseline microbial count for the subjects in this study was 5.4 logio organisms per cm" (n = 13).

Before surgical procedures are performed, it is standard that the proposed operative site be prepared with an effective antimicrobial to reduce the microbial populations residing on the skin and, thereby, the potential for surgery-associated infection. Povidone iodine and chlorhexidine gluconate (CHG) have been the two most prevalent antimicrobial choices for preoperative patient skin preparation over the years. In efficacy trials using human volunteers whose baseline counts exceed 10 microorganisms/cm on moist skin sites, both antimicrobial products commonly demonstrate at least a 3 logio reduction in resident skin flora within 10 minutes of skin preparation [1]. When a formulation contains at least 60% alcohol, these reductions are observed within seconds. 

Figure 1 Example performance data for a brushless surgical hand scrub formulation containing alcohol (TSN) that meets the FDA s current tentative monograph criteria in terms of initial (Day 1) use over a six-hour period. Antimicrobial average log reductions are shown, respectively, relative to the performance of typical 7.5% povidone iodine (PVPI) and 4% chlorhexidine gluconate (CHG) formulations that were tested in accordance with their label instructions using a brush.

This chapter presents neutralization procedures for six topical antimicrobial compounds [9] chlorhexidine gluconate (CHG), iodine (tinctures and povidone-iodine), alcohols (ethyl and isopropyl), triclosan, parachlorometaxylenol (PCMX), and quaternary ammonium compounds (QAC). 

Nowadays, iodine is widely used for the manufacturing of X-ray contrast media, antimicrobial products, as tinctures of polyvinylpyrrolidone-iodine (Povidone-iodine), catalysts in chemical processes (e.g. for the production of acetic acid by carbonylation of methanol in the presence of a rhodium iodide-catalyst (Monsanto process) or an iridium iodide-catalyst (Cativa process)), and also on a smaller scale for the production of pharmaceuticals like thyroid hormones. [ 83 ]... 

Povidone-iodine (PVP-I, polyvinyl pyrrolidon-iodine complex, Betadine, Betaisodona, Braunol, Braunosan H, Disadine D.P., Disphex, Efo-Dine, Inadine, Isodine, Proviodine, Traumasept, Videne, CAS no. 25655-41-8). This is the most widely used iodophor and does not have the irritant properties associated with iodine solutions. At a strength of 7.5% in a surfactant base, povidone-iodine is applied as a surgical scrub, and at 4% is used as a shampoo or skin cleanser. Because of the small amounts of free iodine (less then 1 ppm in a 10% solution), antimicrobial effects are moderate in comparison with iodine solutions. 

Antimicrobial agents can be combined with a suitable thickening and gelling agent to prepare creams and ointments with antimicrobial properties. For example, Betadine Solution and Betadine Cream contain 10 and 5% povidone-iodine respectively. It has been shown that these products are effective against MRS A. 

When iodine and povidone are combined, a chemical reaction takes place forming a complex between the two entities. Some of the iodine becomes organically linked to povidone though the major portion of the complexed iodine is in the form of tri-iodide. Dilution of this iodophor results in a weakening of the iodine linkage to the carrier polymer with concomitant increases in elemental iodine in solution and antimicrobial activity. 

Povidone is an iodophor, that means an iodine carrier which in solutions and on heating releases iodine. However, the disadvantages of iodine (i.e. unpleasant odour, skin irritation, staining of tissue and corrosions of metal surfaces) are diminished. On dilution in water I2, HOI, OI" and I3 are set free, which are responsible for the antimicrobial action of Povidone. The disinfecting effect extends to different classes of micro-organisms including spores and viruses. The most important application of Povidone is the medical disinfection of skin. 

Eye lotions are defined as aqueous solutions. Thus active substances must be soluble at the concentration needed. Eye lotions must be sterile. According to Ph. Eur. eye lotions intended for use in surgical procedures or in first-aid treatment do not contain an antimicrobial preservative and are supplied in single-dose containers, see for example an eye lotion with iodinated povidone (Table 10.11). 

---