3. Cosolvent or Dispersion Stabilizer
Povidone is also increasingly used as a cosolvent or crystal growth inhibitor in injections. This solubilization effect is mainly caused by the combination of and povidone. It is worth noting that since the diameter of the human kidney is about 7 nanometers, the povidone that enters the human blood can only be successfully excreted through the renal tubules when its spiral is less than 7 nanometers, that is, the corresponding molecular weight is less than 30,000. Therefore, the molecular weight of povidone used as an injection should not be greater than 30,000. Since povidone is a product of free radical polymerization, there is a problem of molecular weight distribution. In order to ensure that the povidone used in the injection does not contain products with a molecular weight greater than 30,000, it is recommended to use povidone with an average molecular weight of about 2,500, which is generally used as a cosolvent for injections. The povidones used are mainly povidone K12 and povidone K17.
4. Coating or film-forming agent
In coating, the high adhesion of povidone increases the adhesion of coating to drug base; the excellent dispersibility increases the stability of coating suspension, which can avoid the reaggregation and migration of pigments; the excellent film-forming property can prevent microcracks on the coating surface during drying. K25 and K30 are mainly used as coatings in povidone, and now vinyl pyrrolidone-vinyl acetate copolymers on the domestic market have also been widely used as coatings.
5. Pore-forming agent
In the preparation of poorly soluble matrix or soluble matrix sustained-release preparations, povidone is often used as a pore-forming agent. The release rate is adjusted by adjusting the amount of povidone, and the optimized dissolution curve can be obtained by using a suitable preparation process. High molecular weight povidone K90 can be used to prepare hydrophilic gel sustained-release tablets, and the release rate can be adjusted by changing the ratio of matrix material to dosage.
In addition, the povidone series is also widely used in ophthalmic adjuvants, capsule glidants, etc. With the continuous improvement of domestic preparation level, the application of povidone will become more and more extensive, and its application prospects will be more optimistic.
