Povidone Iodine is a complex of iodine
with polyvinylpyrrolidone. Dried at 105o to constant weight, it
contains 9 - 12% of a available iodine (I). Preparation – Polyvinylpyrrolidone
having an average molecular weight of 40,000 is heated with elemental iodine in
the presence of little water whereby a small amount of the iodine enters into
loose organic union with the polymer to form a complex which contains
approximately 10% of available iodine.
Occurs as yellowish-brown , amorphous powder, having a slight, characteristic odor. Its aqueous solution is acid to litmus.
Soluble in water and alcohol; practically insoluble in chloroform, carbon tetrachloride, ether, solvent hexane, and acetone.
Povidone-Iodine slowly releases its iodine after it has been applied to the surface. The slow release attenuates the antiseptic potency of the iodine, but the prolongation of action is claimed partially to compensate for decreased concentration of free iodine. However, it cannot be considered equivalent to iodine solutions of equal per cent. Indeed, the concentration of free iodine in Povidone-Iodine solution is too low to detect by starch, and it is difficult to see how a strong antiseptic action can be attributed to dissociated iodine. The low content of free iodine, the absence of KI, and the demulcent nature of polyvinylpyrrolodone contribute to the fact that this preparation rarely produces smarting or irritation.
Povidone-Iodine solution contains 85 –
120% of the labeled amount of Iodine. It may contain a small amount of alcohol.