Application of polyvinylpyrrolidone in traditional Chinese medicine

Polyvinylpyrrolidone (PVP) was first synthesized by the German company BASF during World War II as an artificial plasma solubilizer. In the pharmaceutical industry, PVP and cellulose derivatives, acrylic compounds are currently internationally recognized as the most important three kinds of synthetic pharmaceutical excipients, whose average molecular weight is generally expressed by the K value of K-15, K-30, K-60, K-90 and other representative molecular weight of about 10,000, 40,000, 160,000, 360,000. PVP has many excellent properties such as solubility, solubilization, film forming, complexation, adhesion and certain surface activity, especially good biocompatibility without any irritation to the skin, mucous membranes and eyes, so it is widely used in the field of medicine.

1 Used as an adhesive

Because PVP is soluble in both water and some common organic solvents, such as ethanol, it can be used in a variety of formulations. For example, the influence of water and heat can be eliminated by using ethanol solution of PVP as binder for agents sensitive to humidity and heat. The use of PVP solution for hydrophobic drugs can uniformly wet and make the surface of drug particles hydrophilic, which is conducive to increasing the dissolution of drugs.

Xiong Ying et al. determined the prescription with 10% hydroxypropyl methylcellulose as blocking agent, 8% PVP-K-30 as binder and 25% microcrystalline cellulose as filling agent through orthogonal design when developing the total flavone sustained-release tablets of epimedium. The total flavone sustained-release tablets of Epimedium released 50% at 4h and over 90% at 12h. Chen Nanming et al. improved the production process of Jianwei Xiaoshi tablets and changed the granulation method to prepare raw drug fine powder and concentrated liquid and use a certain PVP ethanol solution as an adhesive spray granulation. After the process improvement, the new process can obviously save water, energy, time and materials and greatly reduce the dosage of patients.

The prescription of Xuesaitong oral disintegrating tablets developed by Liu Zhicheng et al. [5] was as follows: 25g total saponin of Notoginseng, 25g mannitol, 40g microcrystalline cellulose, 10g hydroxypropyl cellulose (low substitution), 1g magnesium stearate and appropriate amount of PVP were prepared into 1000 tablets. The disintegrating tablets made of PVP dissolved in 50% ethanol increased the dissolution and dissolution rate of traditional Chinese medicine ingredients.

The solid preparation of traditional Chinese medicine processing powder often uses water, honey, sucrose as binder and has good forming properties. For the solid preparation of spray dried powder of traditional Chinese medicine, the use of these adhesives brings considerable difficulties to the molding process due to the strong moisture absorption and poor plasticity of the powder. Chen Zhijie et al. [6] studied the effects of adhesives on the formability and pellet quality of solid preparations prepared from Chinese medicine processed powder and Chinese medicine spray dried powder, and found that the rapid stirring granulation technology was used to prepare Chinese medicine spray dried powder with a ratio of 2∶1 and 90% ethanol of 3% to 5% PVP-K-30 as the adhesive forming process with good operability The pellet yield is more than 80%, which successfully solves the difficult problem in pellet forming process.

2 Used as a solid dispersant

In order to improve the bioavailability and stability of insoluble drugs, a solid dispersion technique can be used in which the water-insoluble drug is dispersed in a water-soluble solid carrier in a very fine particle or molecular state. When the mixture or a molten solidified body is placed in the liquid, the soluble carrier immediately dissolves and the drug is released in a very fine particle Increase by several times.

For example, Zhao Tie et al. [7] prepared a variety of solid dispersions of pentalinol by directly dissolving the carrier material in pentalinol extract solution and then removing the solvent. Using schisandrin as the index component, they studied and compared their apparent solubility and in vitro dissolution and found that the apparent solubility of the active component in the solid dispersions of pentalinol -PVP-K-30 with a ratio of 1∶3 was higher than that of pentalinol gum The contents of the capsule were significantly increased to 5.06μg/ml in water. Water dispersion (including dissolution of up to 43.2% of the drug less than 0.22μm). It was concluded that the apparent solubility and in vitro dissolution of the active components in pentarenol could be significantly improved by PPVP-K-30 solid dispersion.

Liu Yuwen et al. prepared solid dispersions using PVP as carrier to improve the solubility of active components of schisandra chinensis. Using β-cyclodextrin inclusion technology to improve the preparation process of schisandra chinensis in Ganziling capsules and using artificial gastric juice as dissolution medium, the solubility and dissolution of the finished products under different preparation processes were determined by ultraviolet spectrophotometry. It was found that the cumulative dissolution rate of solid dispersions was more than 50% in the artificial gastric juice within 5min, which was significantly higher than that of the original process and inclusion compound. The results indicated that PVP could be used as a drug carrier system for the solubilization of schisandra chinensis, and the bioavailability and clinical efficacy of schisandra Chinensis preparations could be improved by solid dispersion technology.

Jiang Yongnan et al. prepared coprecipitates of flavonoid phospholipid complex (EFL) and PVP by solvent volatilization method. The cumulative dissolution of PVP copolymer capsules with different proportions was investigated by in vitro dissolution method. It was found that the cumulative dissolution rate of EFL: PVP (1∶3) co-precipitate capsules was significantly higher than that of physical mixture and Shengning tablets, indicating that solid dispersion technology really improved the dissolution rate and dissolution rate of drugs. In addition, some water-insoluble triterpenoids such as ursolic acid, oleanolic acid, ursolic acid and flavonoids such as quercetin extracted from traditional Chinese medicine have also been reported as solid dispersions.

3 Used as a pore-causing agent for coating materials

Some permeable slow release or controlled release coating materials, such as cellulose acetate, ethyl cellulose and non-permeable material silicone elastomer, are often unable to dissolve and permeate from the chip core or pill core through the coating layer. Therefore, some pore-causing agents are often added to the coating solution of these materials to increase the permeability of the coating film and obtain the required drug release rate. The properties of PVP determine that it can be used as a porous agent for sustained release coating, as well as for insoluble skeleton sustained release tablets and waxy skeleton sustained release tablets.

When Pan Qi et al. studied Zuo Jin film controlled sustained-release capsules, ethyl cellulose was used as the film-forming material and water insoluble substance in the release medium, so that the formed film always maintained a certain integrity. PVP is a water-soluble pore-causing agent that forms drug release pores in the release medium. Stearic acid is a drug dissolution blocker and can increase the ductility of pellets. It was found that by controlling the amount of ethyl cellulose and PVP (3:1 is suitable) and adding proper amount of stearic acid, a better slow-release property could be obtained.
Although PVP has begun to be used in traditional Chinese medicine preparations, there is still a big gap compared with its widespread use in the field of medicine and health. With the deepening of research, PVP is expected to be more widely used in modern Chinese medicine dosage forms. Therefore, we should not only strengthen the development of new pharmaceutical excipients, but also pay attention to the promotion and application of existing new excipients, in order to continuously improve the quality of traditional Chinese medicine preparations, promote the reform of traditional Chinese medicine dosage forms, and develop more new high-quality traditional Chinese medicine preparations.