【Detail】

Owing to PVP’s characteristics of good solubility, solubilization, physiological compatibility, adhesive ability and complexing power in the field of medicine, medical treatment and health, PVP can be used as bonding agent, excipient, drug coating, disintegrating agent, cosolvent, bactericide, disinfectant, solubilizer, alleviator, capsule shell, dispersion stabilizer, film-forming agents and so on. In some developed countries, such as United States, Germany, Japan, the application of PVP in the field of medical, medicine treatment and health accounts for about 40%~55% of consumption. At present, the amount and function of PVP in the field of medical, medicine treatment and health are listed in the following table:

Application of PVP as drug accessories

PVP has good adhesive property and strong ability to dissolve. After tablets containing PVP are taken, first of all, tablets will be dissolved quickly in the digestive tract to make the tablets local swell and disintegrating to release drugs debris, which accelerates the dissolution and absorption of tablets, releases the effect of tablets quickly. Because PVP can be dissolved in water and many organic solvents,  PVP has been widely used in pharmaceutical tablets, especially in foreign countries. common drugs which uses PVP as adhesive are as follows :compound sulfamethoxazole, aspirin, compound aspirin, paracetamol, vitamin C, dipyridamole, dimethyl tetracycline, clonidine, benzene sulfonamide, compound analgesic, chewing tablets. These drugs will be taken for examples to illustrate the prescription:

Aluminum hydroxide gel 0.4g

Magnesium hydroxide fine powder 0.08g
sugar powder 0.02g
Mannitol fine powder 0.2g
10%PVP alcohol（ 50% ）solution 0.03g
Magnesium stearate  0.015g
peppermint oil 0.0005g

PVP which is used as a bonding agent in The tablets of the drug is mainly PVP-K30. The dosage depends on the requirement of The tablets of the drug of mechanical strength and the nature of the drug, and is 0.5~5.% in general.

Besides, PVP, as an auxiliary drug, has another important function which is  coprecipitator. Some drugs have good efficacy, but the fatal flaw is that they are much soluble, resulting in reducing the utilization the bioavailability greatly. Water-soluble substances can be used to be coprecipitation with some certain drugs to increase the solubility and the speed of dissolution of drug and realize the effect of reducing the dose and improving the efficacy. As coprecipitation of insoluble drug, PVP is getting widely used.

The reason why PVP can be used as a coprecipitator is that the molecules of carbonyl O in PVP can be combined with the molecules of active hydrogen bonds in insoluble drug to make the relatively small drug molecules which become amorphous enter big molecules in PVP. What’s more, hydrogen bonds do not change the nature of easily solubility in water of PVP, so insoluble drug molecules scatter in molecules of PVP through hydrogen bonds to make it easier to dissolve. After some insoluble drugs and PVP become coprecipitation, solubility changes, which can be showed as follows:

Insoluble drugs in the body can increase solubility and the bioavailability at the same time, for example, the bioavailability increases 1.55times after coprecipitation between phenytoin and PVP. The increase of solubility of insoluble drugs which have coprecipitated relates to the molecular weight and the amount of PVP.  When the amount (quality) of PVP is the same, the increase of solubility of drug will decrease according to the order: PVP-K15>PVP-K30>PVP-K90, because the solubility of the PVP itself changes in accordance of PVP-K15>PVP-K30>PVP-K90. Generally speaking, PVP-K15 can be used more.

The increase of solubility of coprecipitation between insoluble drugs and PVP is complicated when the dosage of PVP changes. As a certain molecular weight of PVP, every PVP  molecule which can combine with molecule of drug is unchangable. Insoluble drug always has crystals status. When the dosage of PVP is less than drug which PVP will combine with so that it will become amorphous and decentralized, drug is mainly in crystalline state, and solubility has small changes . PVP must meet a certain demand to make drug become amorphous dispersion, therefore, the solubility can have a significant increase in order to achieve the goal of dissolution and then absorption rapidly. It’s not the same when different drugs meet the PVP’s dosage, they become coprecipitated with amorphous and dispersed PVP, such as cyclohexyl acetate, whose numerical value is 70%. Other drugs, such as b - carotene, chloramphenicol and dexamethasone, partially hydrogenated effects of prednisone, streptomycin, tetracycline, testicles can slao increase solubility and bioavailability in the body through coprecipitation with PVP.

Similarly, the association between molecules of PVP and hydrogen bonds of drug molecules have the effect of delay and slow-release influence, opposite to  solubilizationand and quick impact. After controlling the degree of association between molecules of PVP and drug molecules, drug molecules which have associated be released slowly in the body to delay the speed of dissolution in order to extend the effect. PVP have the effect of proloning the influence of drugs on penicillin, chloramphenicol, insulin, sodium salicylate, procaine, cortisone.

PVP can be used as drugs’s bonding agent, solubilizer, disintegrating agent, retardant in solid drugs, at the same time PVP can also be used as a coat of drug membrane and capsule shell and controlled - release film. It’s difficult for the coat of drug membrane and capsule shell containing PVP to be broken in a dry environment. An appropriate amount of PVP and other insoluble polymercan be made of permeable film with different thicknesses and different apertures. Hence, the rate of drugs through the membranes can be adjusted to realise the effect of controlling the release of efficacy.

Application of PVP in liquid medicines

In addition to the numerous applications of PVP in solid drugs mentioned above, PVP also plays an important role in eyedrops and injections . For example, for some injections, PVP can has the association other drugs. As a result, on one hand,  PVP can help solubilize, on the other hand, PVP has the disperse and steady effect on some drugs that will crystallize or precipitate in some places for a long time. PVP can play the role of dispersion stability. PVP-K7 can reduce the irritation to eyes and extend the time of effect eyedrops when used in eyedrops.