Povidone-iodine complex

In 1985 a working group of the Federal German Medical Association issued a number of recommendations for the safe use of povidone-iodine complexes (13). They remain valid and can be summarized as follows ... 

A simple and rapid method for the quantitative determination of povidone is by photometry of the povidone-iodine complex [18,19] ... 

The most versatile method for quantitatively determining povidone is probably the photometric measurement of the povidone-iodine complex described in Section 2.3.i.2. It has been successfully tested on samples that also contained a series of auxiliaries and drugs [18]. 

A calibration curve must be established to determine the copovidone content from the absorbance (Fig. 100). The absorbance of the iodine complex is slightly less than that of the povidone-iodine complex. 

Consider using organic complexes like iodophors and povidone-iodine that get trapped in surfactant micelles and release iodine as a disinfectant upon dilution, for products that contact human skin. 

Iodophors are complexes of iodine with a surface-active agent such as polyvinyl pyrrolidone (PVP povidone-iodine). Iodophors retain the activity of iodine. They kill vegetative bacteria, mycobacteria, fungi, and lipid-containing viruses. They may be sporicidal upon prolonged exposure. Iodophors can be used as antiseptics or disinfectants, the latter containing more iodine. The amount of free iodine is low, but it is released as the solution is diluted. An iodophor solution must be diluted according to the manufacturer s directions to obtain full activity. 

It is widely employed as a disinfectant in medicine (Povidone-iodine) because of its mildness, low toxicity, and water solubility. According to the U.S. Pharmacopeia, l ovidone-iodme is a free-flowing, brown powder dial contains from 9-12% available iodine. 11 is soluble in water and lower alcohols. When dissolved in water, the uncomplexed free iodine level is very low however, tine complexed iodine acts as a reservoir and by equilibrium replenishes the free iodine lo the equilibrium level. This prevents free iodine from being deactivated because the free form is continually available at effective biocidal levels from this large reservoir. PVP will interact with other small anions and resembles serum albumin and other proteins in this regard. It can be salted in with anions such as NaSC.N or out with NasSOa much like water-soluble proteins. 

Iodophors are labile complexes of elemental iodine with macromolecular carriers that both increase the solubility and provide sustained release of iodine. Povidone-iodine is a water-soluble iodophor that is used as an antiseptic and is said to be free of the undesirable effects of iodine tincture. However, iodine can be absorbed from it through burned areas (17), vaginal mucosa (18), oral mucosa (19), and in children even with normal skin (20). Povidone-iodine is discussed in a separate monograph under the title Polyvidone. 

Povidone-iodine is a macromolecular complex (poly-I(I-vinyl-2-pyrrolidinone) that is used as an iodophor. It is formulated as a 10% applicator solution, a 2% cleansing solution, and in many topical formulations, for example aerosol sprays, aerosol foams, vaginal gels, ointments, and mouthwashes. Because it contains very little free iodine (less than 1 ppm in a 10% solution) its antibacterial effectiveness is only moderate compared with that of a pure solution of iodine. 

When povidone-iodine is used as a rinsing solution in body cavities, absorption of the whole macromolecular complex is possible. The complex has a molecular weight of about 60 000 and cannot be eliminated by the kidneys or metabolically. It is filtered by the reticuloendothelial system (4,8,9). 

Povidone-iodine causes concentration-dependent damage to cells and clusters. The effect is most pronounced for isolated cells, but it is also detectable in more complex tissues. Clinical experience with burn victims cannot rule out the possibility that the healing process may be slightly retarded. However, this deficiency may be balanced by an appropriate microbicidal effect on the healing edge (22). 

The molecular adduct formation properties of povidone may be used advantageously in solutions, slow-release solid-dosage forms, and parenteral formulations. Perhaps the best-known example of povidone complex formation is povidone-iodine, which is used as a topical disinfectant. 

The only known exceptions, i.e. substances that become less soluble or even precipitate, are polyphenols, e.g. tannin, and hexylresorcinol [10,108]. In general, all complexes with povidone are formed only under acidic conditions and are unstable and can decompose in the alkaline pH range. Typical examples are cobalt [388] and the disinfectant, povidone-iodine [9] in which all the iodine, with the exception of a few ppm of free iodine, is complexed (Fig. 21). 

The ability to form complexes with such a large number of substances is a special feature of polyvinylpyrrolidone (Section 2.2.7). The complexes formed are almost always soluble and are stable only in an acid medium. This property can be used to increase the solubility of drugs in liquid dosage forms, as in the case of povidone-iodine. In solid dosage forms, the ability to form complexes is used to increase bioavailability. A reduction in the local toxicity of certain drugs can also be achieved by complexation with povidone. A special use for the complexation properties lies in the stabilization of proteins and enzymes in diagnostics. 

The photometric determination of the iodine complex used to determine povidone can also be used for copovidone, though the colour intensity of the iodine complex only reaches its maximum after about 30 min, after which it slowly fades. Thus, it must be measured after 30 min, instead of 10 min, as in the determination of povidone [18]. 

More recently available is an aqueous solution of an iodine complex of polyvinylpyrrolidone, or povidone. It does not sting when applied to open wounds. 

Figure 96.1 The PVP-I complex. Povidone-iodine (PVP-I), a complex of the polymer polyvinylpyrrolidone and iodine, is a water-soluble powder containing 10% iodine. The available iodine content in the preparation varies from 0.05 to 1%. PVP-I solutions used for disinfection of the skin or wounds have a 1 % iodine content.

X0-1-pyrrolidinyl) ethylene) iodine complex Polyvinylpyrrolidone-iodine complex Povidone-iodine... 

PVP is a physiologically inert and biologically compatible polymer. PVP is known to reduce significantly the toxicity and irritant effects of many medications. PVP can form complexes with a variety of substances. For example, the PVP-iodine complex in the form of povidone or Betadine aqueous solution is the most widely used antiseptic in hospitals. It significantly reduces the toxicity and staining effect of the tincture of iodine solution but retains the germicidal activity of the iodine. 

Dmgs made using aqueous solutions of iodine complexes with organic compounds (povidone, polysaccharides) also may contain ions I , I2,13, Ij , Ie, HOI, 01 , 102 influence of initial concentrations of molecular iodine and iodide, and also pH (0-14) on the equilibrium concentration of molecular iodine and the above ions was studied using an aqueous solution of iodine and iodide ion [45]. Based on the studies, the authors have come to the conclusion, that the aqueous solutions of complexes of iodine with organic compounds actually contain only I , 13 and I2. 

Povidone-iodine (Betadine) is a water-soluble iodine complex which retains the broad-range microbiocidal activity of iodine without the undesirable effects of iodine tincture. However, toxicity still occurs from povidone-iodine percutaneously absorbed, mainly when it is used on large areas of burnt skin or on neonates. This subject is comprehensively dealt with by Postellon and Aronow (1990). 

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. 

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