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Table of contents
4. Use as pharmaceutical excipients
5. Regulate drug release pattern
7. Application in liquid drugs
In drug development and production, many drugs have extremely low solubility in common solvents due to their complex chemical structures. This hinders the dissolution of drugs in the gastrointestinal tract and other parts, resulting in low absorption efficiency and difficulty in exerting drug efficacy. Polyvinylpyrrolidone (PVP) brings hope for solving this problem.
The lactam group in the PVP molecule is hydrophilic, and the molecular chain is helical, which can create a special microenvironment for drug molecules. When PVP comes into contact with poorly soluble drugs, it will disperse and encapsulate the drug molecules through interactions such as hydrogen bonds and van der Waals forces to form a stable solid dispersion or complex.
Taking naproxen as an example, it is difficult to dissolve in water, and its dissolution and absorption after oral administration are slow, which limits its efficacy. Researchers used PVP for the preparation of naproxen, and the resulting naproxen-PVP solid dispersion had a greatly improved dissolution rate in simulated gastric fluid and could remain stable even after being stored at room temperature for several months.
Similarly, in the research and preparation of indomethacin and chloramphenicol, PVP showed solubilization effect. Indomethacin is poorly soluble, which affects its bioavailability. After the introduction of PVP, the drug dissolution and absorption is improved, the blood drug concentration is increased, and the therapeutic effect is enhanced. Chloramphenicol is better soluble with the help of PVP, and can quickly exert its antibacterial activity to treat infectious diseases.
1. Key role in controlled-release tablets
In the preparation of controlled-release tablets, PVP is the core skeleton or pore-forming agent. After the tablet enters the gastrointestinal tract, water penetrates, and PVP swells with water to form a gel layer. The drug is slowly released through the pores of this layer by diffusion and skeleton dissolution. Researchers adjust the dosage, molecular weight and ratio of PVP to excipients to accurately control the drug release time to meet different treatment needs. For example, for cardiovascular disease controlled-release tablets, after optimizing PVP parameters, the drug is released stably and uniformly for 24 hours to maintain blood drug concentration.
2. Unique advantages in the development of transdermal patches
In the development of transdermal patches, PVP nanofibers made with the help of electrospinning technology have significant advantages. Its high specific surface area can load a large amount of drugs, and the pore size can be adjusted as needed. In local sustained-release systems such as aspirin and ibuprofen, drug-loaded PVP nanofiber patches can continuously release drugs locally on the skin for several hours in experiments and trials, relieving inflammatory pain and reducing systemic absorption and side effects.
3. Optimization of drug release in eye drops
In the field of eye drops, PVP can be added to adjust viscosity, delay drug loss, and allow drugs to be slowly and continuously released in the eye. For example, after adding PVP to eye drops for the treatment of glaucoma, the drug maintains effective concentration for a longer time, more effectively controls intraocular pressure, and improves the treatment experience.
4. Potential application expansion in other drug delivery systems
In emerging drug delivery systems, PVP has great potential. In microsphere preparations, PVP participates in the preparation, affecting microsphere degradation and drug release. In anti-tumor microspheres, PVP helps drugs to be slowly released locally in tumors, enhancing efficacy and reducing side effects. In liposome drug systems, PVP modifies the surface, regulates drug release, improves targeting and stability, and helps treat major diseases.
When drugs are stored and used, oxygen and moisture are the "culprits" that threaten their stability. When the active groups of drug molecules come into contact with oxygen or water, they are prone to oxidation and hydrolysis, causing the drug to deteriorate and reduce its efficacy. Polyvinylpyrrolidone (PVP) protects drug stability with its unique chemical properties.
PVP molecules contain active groups such as nitrogen atoms and carbonyl groups, which can be tightly bound to the corresponding groups of drug molecules through hydrogen bonds, van der Waals forces, and electrostatic effects. The PVP molecular chain wraps around the drug molecules, forming a protective film on its surface to isolate oxygen and water, reducing the risk of adverse drug reactions.
Take vitamins as an example. Vitamin C has strong reducing properties, and the enediol group is easily oxidized and inactivated. After combining with PVP, the two form a stable complex through hydrogen bonds. PVP blocks oxygen, greatly slowing down the oxidation rate of vitamin C, and extending the oxidation and deterioration time of the preparation several times. Vitamin E is fat-soluble and easily oxidized under light, high temperature and aerobic environment. PVP combined with it not only improves its dispersibility in aqueous solution, but also forms a physical barrier, enhances its storage stability, extends its shelf life, and ensures its antioxidant effect.
4. Use as pharmaceutical excipients
In the field of pharmaceutical preparations, PVP is widely used and has multiple functions. It can be used as a variety of pharmaceutical excipients such as binders, excipients, coating agents, disintegrants, cosolvents, bactericides and disinfectants, solubilizers, sustained-release agents, capsule shells, dispersants, stabilizers, film-forming agents, etc. In the tablet preparation scenario, PVP is added to the tablet sugar coating slurry or film coating solution. Its unique molecular structure can form a close connection with the coating material and the tablet base, thereby significantly increasing the adhesion of the coating material to the tablet base, allowing the coating to fit firmly. In film coating solutions with coloring requirements, PVP can act as a pigment dispersant with its excellent dispersing properties, promote uniform distribution of pigments, ensure uniform and beautiful coating color, and improve the appearance quality of the drug.
5. Regulate drug release pattern
1. The key to PVP regulating the drug release rate lies in its own characteristics. When the PVP concentration is adjusted, when the concentration is high, the network structure it forms is tight, the drug diffusion path is blocked, the release rate is significantly slowed down, and the drug is sustained release.
2. The molecular weight of PVP also affects drug release. High molecular weight PVP has a long molecular chain and a strong bond to the drug, making it more difficult for the drug to escape. It can accurately achieve a controlled release effect and ensure that the drug works smoothly and lastingly.
3. Taking antibiotics as an example, PVP and some antibiotics are made into sustained-release preparations, which can slowly release drugs in the body. This greatly prolongs the drug action time, significantly reduces the number of times patients take medication, greatly improves medication compliance, and makes the treatment process more convenient and effective.
In the field of solid medicine, PVP can be described as a "multi-talented person". As a binder, it can make drug powders closely attached to each other, ensuring that solid dosage forms such as tablets are firmly formed. When acting as a solubilizer, it helps to dissolve poorly soluble drugs and improves the absorption of drugs in the body. In the production of drug film coats and drug capsule shells, PVP shows excellent performance. The shells made are tough and durable in a dry environment and are not easy to break. When an appropriate amount of PVP is cleverly combined with other insoluble polymers to make permeable membranes with different thicknesses and pore sizes, the rate at which the drug passes through the membrane can be accurately controlled to effectively achieve controlled-release efficacy, laying a solid foundation for the efficient application of solid drugs.
7. Application in liquid drugs
In the field of injections, PVP exhibits dual effects due to its unique association with drugs. Specific groups in its molecular structure attract drug molecules to form association complexes. This process not only increases the solubility of drugs in solvents and significantly plays a solubilizing role, but also effectively prevents drug molecules from aggregating during storage, prevents crystallization or precipitation after being stored for too long, and maintains the stability of the injection due to the steric hindrance effect. For the application of eye drops, PVP has good biocompatibility and can reduce the irritation of drugs to the eyes. At the same time, its moderate viscosity can delay the loss of eye drops from the eyes, significantly prolong the action time of eye drops in the eyes, enhance the therapeutic effect, and bring patients a more comfortable and efficient treatment experience.
PVP is crucial in drug sustained-release systems through its applications in improving drug solubility, enhancing stability, controlling release rates, and various drug dosage forms.
In terms of solubility, PVP forms solid dispersions or complexes with poorly soluble drugs, changes the physical state of the drug, increases the contact area with the solvent, significantly improves solubility, helps drug absorption, and lays the foundation for drug efficacy. In terms of stability, PVP uses hydrogen bonds and van der Waals forces to interact with drug molecules to form a protective film on the surface of the drug, isolate oxygen and moisture, and improve the stability of the drug during storage and transportation.
In drug release rate control, PVP is used as a skeleton for controlled-release tablets, nanofibers for transdermal patches, and eye drops to adjust viscosity. PVP accurately controls release according to different dosage forms and treatment needs. Stable blood drug concentrations ensure that the drug continues to act on the lesion site, optimize the treatment effect, and reduce toxic side effects caused by excessive concentrations. At the same time, the drug's action time is extended and the number of dosing times is reduced, which greatly improves patient compliance with medication and ensures smooth progress of treatment.