Hydroxypropyl methylcellulose (HPMC) is a polymer material commonly used in pharmaceutical preparations. Due to its excellent physical and chemical properties, it plays an important role in tablet manufacturing. HPMC can be used as a film former, controlled release agent, adhesive, thickener, etc., giving tablets good structure and function.
1. Film former
The role of HPMC as a film former is mainly reflected in the surface coating of controlled release tablets. Tablet coating is carried out for the purpose of controlling the release rate of drugs, protecting drugs from environmental influences, and improving the appearance of drugs. In controlled release preparations, the film formed by HPMC can adjust the release rate of drugs, ensure that the drugs are released in specific parts of the gastrointestinal tract, and achieve the best therapeutic effect.
Mechanism of action: The film formed by the HPMC film former can achieve controlled release of drugs by controlling the entry of solvents and the dissolution of drugs. The thickness and composition of the film can adjust the dissolution rate to meet the release requirements of different drugs.
Impact: Tablets using HPMC as a film-forming agent can dissolve slowly in the stomach, avoid sudden drug release, improve drug utilization, and reduce drug irritation to the gastrointestinal tract.
2. Controlled release agent
HPMC is often used as a matrix material in controlled-release tablets to regulate the release rate of drugs by forming a gel barrier. The role of a controlled-release agent is to ensure that the drug is released evenly within a specific time to maintain the effective concentration of the drug in the body, reduce the number of dosing times, and improve patient compliance.
Mechanism of action: In aqueous media, HPMC can quickly hydrate and form a colloidal network structure, which controls the diffusion and release rate of the drug. When the tablet comes into contact with water, HPMC absorbs water and swells to form a gel layer, through which the drug diffuses out of the body, and the release rate depends on the thickness and density of the gel layer.
Impact: HPMC as a controlled-release agent can stabilize the drug release rate, reduce the fluctuation of blood drug concentration, and provide a more stable therapeutic effect, especially for drugs for the treatment of chronic diseases.
3. Binders
In the process of tablet preparation, HPMC is often used as a binder to enhance the mechanical strength of tablets and ensure the integrity of tablets during storage, transportation and administration.
Mechanism of action: HPMC, as a binder, can form a strong bond between particles, so that powders or particles are bonded and formed into a solid tablet. This process is usually carried out through wet granulation technology, where HPMC dissolves in an aqueous solution to form a viscous solution, and forms a stable tablet after drying.
Impact: HPMC binders can improve the compressive strength and hardness of tablets, reduce the risk of disintegration or fragmentation, and thus improve the quality and stability of tablets.
4. Thickeners
HPMC can also be used as a thickener in liquid preparations to adjust the rheological properties of the preparations and increase viscosity.
Mechanism of action: HPMC has high viscosity in water and can effectively increase the viscosity of the liquid, improve the suspension and stability of the drug, and prevent sedimentation.
Impact: Adding HPMC to liquid drugs can improve the uniformity of the drug, make the drug components evenly distributed throughout the preparation, and ensure consistent dosage each time.
Characteristics of Hydroxypropyl Methylcellulose
1. Physical and Chemical Properties
HPMC is a nonionic cellulose ether with good water solubility and thermal gelation. It dissolves rapidly in cold water to form a transparent solution, while when heated, the solution turns into a gel.
2. Biocompatibility
HPMC has good biocompatibility and safety, and is not prone to cause immune response or toxic effects, so it is widely used in the pharmaceutical and food fields.
3. Environmental stability
HPMC has good stability to environmental factors such as temperature and pH value, and is not prone to degradation or denaturation, which ensures the stability of drug preparations during storage.
Examples of HPMC Application in Tablets
1. Controlled Release Tablets
For example, in nifedipine sustained-release tablets used to treat hypertension, HPMC is used as a matrix material to control the slow release of the drug, reduce the frequency of administration, and improve patient compliance.
2. Enteric-coated tablets
In enteric-coated tablets of proton pump inhibitors (such as omeprazole), HPMC acts as a film-forming agent to protect the drug from being destroyed by gastric acid and ensure that the drug is effectively released in the intestine.
3. Oral fast-dissolving tablets
In oral fast-dissolving tablets for the treatment of allergic rhinitis, HPMC acts as a thickener and adhesive to provide rapid dissolution and uniform release, improving the taste and taking experience of the drug.
Hydroxypropyl methylcellulose is widely used in the preparation of various tablets due to its excellent film-forming, controlled release, adhesiveness and thickening properties. HPMC can not only improve the physical properties and stability of tablets, but also optimize the therapeutic effect of drugs by adjusting the release rate of drugs. With the development of pharmaceutical technology, the application of HPMC will become more diversified, providing more possibilities for the innovation of drug preparations.