HPMC (Hydroxypropyl Methylcellulose) is a water-soluble polymer obtained by modifying natural cellulose. It is widely used in pharmaceutical preparations, food, cosmetics and industrial fields. In sustained-release pharmaceutical preparations, HPMC has become an important drug release regulator due to its excellent film-forming property, controlled release properties and biocompatibility.
1. Properties and characteristics of HPMC
HPMC is a cellulose derivative obtained by hydroxypropyl and methylation modification, with good water solubility and gelation. Its chemical structure determines that it can form a uniform and stable gel network in water, has good film-forming properties, and can control the release rate of drugs. Specifically, HPMC has the following key characteristics:
Water solubility and solubility regulation: KimaCell®HPMC is easily soluble in water and forms a viscous solution. The solubility is affected by the degree of substitution of methyl and hydroxypropyl in the molecule. HPMC with different degrees of substitution has different dissolution rates and gelation properties, and drug release can be precisely controlled by adjusting its chemical structure.
Biocompatibility and low toxicity: HPMC, as a natural derivative, has good biocompatibility and low toxicity, and is often used in oral preparations, ophthalmic preparations, etc.
Film-forming property: HPMC can form a stable film layer in water, which helps to control drug release.
2. Mechanism of action of HPMC in sustained-release preparations
Sustained-release preparations refer to the use of physical or chemical methods to extend the action time of drugs in the body, so that their release rate is slow and uniform, so as to achieve a sustained therapeutic effect. The main mechanism of action of HPMC in sustained-release preparations is as follows:
Gelation: HPMC can form a gel in water after dissolution, and the drug is embedded in it. The formation speed and structure of the gel determine the release rate of the drug. Usually, after the gel layer of HPMC absorbs water and swells in the gastrointestinal tract, the drug is slowly released by diffusion, dissolution, etc.
Membrane controlled release: HPMC can be used as a membrane material to wrap the drug inside it to form a thin film coating structure to control the dissolution rate of the drug. This membrane controlled release structure can slowly disintegrate or dissolve in the gastrointestinal tract to release the drug.
Dissolution rate regulation: The molecular structure and substituents of HPMC will affect its swelling and dissolution rate, and thus affect the release rate of the drug. HPMC with a low degree of substitution has a slower dissolution rate and is suitable for long-acting preparations; while HPMC with a high degree of substitution is suitable for faster drug release.
3. Application types of HPMC in sustained-release preparations
Oral sustained-release preparations
In oral sustained-release preparations, HPMC is often used to prepare water-soluble or water-insoluble sustained-release dosage forms. For example, HPMC is often used to prepare sustained-release tablets, capsules, granules, etc. By mixing drugs with HPMC, a drug carrier system can be prepared to control the release process of drugs in the gastrointestinal tract. For example, in the gastrointestinal environment, HPMC absorbs water and swells to form a gel film, which controls the release rate of the drug and achieves a long-term maintenance of the drug effect.
Controlled-release microspheres and microparticles
HPMC is also commonly used to prepare controlled-release microspheres and microparticles, which can achieve slow release of drugs in the body through gelation or membrane. By selecting the appropriate HPMC model and drug loading, an accurate drug release curve can be achieved, so that the drug maintains a stable concentration in the body.
Enteric-coated preparations
When preparing enteric-coated preparations, HPMC as a membrane material can withstand gastric acid and dissolve or swell in the small intestine environment, thereby achieving directional release of drugs. This technology is widely used in drugs that are sensitive to gastric acid.
Local sustained-release preparations
In addition to oral preparations, HPMC is also commonly used in local sustained-release preparations in the fields of ophthalmology and dermatology. In ophthalmic preparations, HPMC can be used as an eye gel to prolong the retention time of the drug in the eye and achieve slow release.
4. Advantages and disadvantages of HPMC in sustained-release preparations
Advantages:
Strong controllability: The solubility, gelation speed and colloidal structure of HPMC can be controlled by changing its molecular weight, degree of substitution and other parameters to achieve the ideal drug release effect.
Good biocompatibility: HPMC is non-toxic and harmless in the body, compatible with a variety of drug ingredients, and widely used in various preparations.
Wide adaptability: KimaCell®HPMC is not only suitable for oral preparations, but also can be used in various types of sustained-release preparations such as ophthalmic and skin preparations.
Easy operation: HPMC is a widely used excipient with a simple preparation process and can produce a strong gel effect at a low concentration, and will not cause adverse effects on the drug during the preparation process.
Disadvantages:
Environmental sensitivity: HPMC is sensitive to temperature and pH in aqueous solution, which may lead to instability during drug release.
Limited sustained release effect: In the controlled release process of some drugs, the sustained release ability of HPMC may not be as good as other synthetic polymer materials, such as polyvinyl alcohol (PVA).
Difficulty in controlling high-dose drugs: When the drug loading is too high, the controlled release ability of HPMC may be insufficient, resulting in too fast or uneven drug release rate.
As an important polymer material, HPMC has broad application prospects in sustained-release drug preparations. It can effectively regulate the release rate of drugs and prolong the duration of drug efficacy by forming structures such as gels and membranes. With the development of formulation technology, the application of HPMC in sustained-release preparations will become more diversified and precise, but it is still necessary to reasonably select the appropriate HPMC type and preparation method according to the characteristics of the drug and its release requirements.
Post time: Jan-09-2025