Vinylpyrrolidone-vinyl acetate copolymer Copovidone

Water-soluble vinylpyrrolidone-vinyl acetate copolymer contains the two components in a ratio of 6 4. It is produced in the same way as soluble polyvinylpyrrolidone, by free-radical polymerization reaction with an organic peroxide as initiator (Fig. 5). As vinyl acetate is not soluble in water, the synthesis is conducted in an organic solvent such as 2-propanol. 

Because of its vinyl acetate component, copovidone is somewhat more hydrophobic and gives less brittle films. This gives the product its favourable properties as a soluble binder and film-forming agent, particularly for solid dosage forms. 

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Two commercial products of the vinylpyrrolidone-vinyl acetate copolymer are available in the market having the pharmaceutical quality required by the Pharmacopoeias. Table 151 mentions the tradenames and producers of these copovidone products. 

Table 151. Vinylpyrrolidone-vinyl acetate copolymer 6+4 of pharmaceutical quality (= copovidone) in the market...

Similar results are reported in the literature when Kollidon VA 64 is compared to povidone (Kollidon K 25, K 30, and 90 F). Copovidone absorbs about three times less water than the other soluble Kollidon K 25, 30, and 90F after seven days at 25 °C up to 80% relative humidity [62], Kollidon VA 64 is manufactured by free-radical polymetization of 6 parts of vinylpyrrolidone and 4 parts of vinyl acetate in 2-propanol. A water-soluble copolymer with a chain structure is obtained. In contrast to the soluble grades of Kollidon, the number 64 is not a K value but the mass ratio of the two monomers, vinylpyrrolidone and vinyl acetate. The K value of Kollidon VA 64 is of the same order of magnitude as that of Kollidon 30. Synonyms for Kollidon VA 64 are copovidone, copovidonum, copolyvidone, copovidon, and PVP-VAc-copolymer [Eur. Ph., Japanese Pharmaceutical Excipients, and USP National Formulary (NF)] [63],... 

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