In the pharmaceutical field, sodium carboxymethylcellulose (CMC) and hydroxypropyl methylcellulose (HPMC) are two commonly used pharmaceutical excipients with different chemical properties and functions.
Chemical structure and properties
CMC is a water-soluble cellulose derivative obtained by converting part of the hydroxyl groups of cellulose into carboxymethyl groups. The water solubility and viscosity of CMC depend on its degree of substitution and molecular weight, and it usually behaves as a good thickener and suspending agent.
HPMC is obtained by replacing part of the hydroxyl groups of cellulose with methyl and hydroxypropyl groups. Compared with CMC, HPMC has a wider solubility, can be dissolved in cold and hot water, and exhibits stable viscosity at different pH values. HPMC is often used as a film former, adhesive, thickener and controlled release agent in pharmaceuticals.
Application field
Tablets
In the production of tablets, CMC is mainly used as a disintegrant and adhesive. As a disintegrant, CMC can absorb water and swell, thereby promoting the disintegration of tablets and increasing the release rate of drugs. As a binder, CMC can enhance the mechanical strength of tablets.
HPMC is mainly used as a film former and controlled release agent in tablets. The film formed by HPMC has excellent mechanical strength and wear resistance, which can protect the drug from the influence of the external environment. At the same time, the film-forming properties of HPMC can also be used to control the release rate of the drug. By adjusting the type and dosage of HPMC, a sustained release or controlled release effect can be achieved.
Capsules
In capsule preparation, CMC is less used, while HPMC is widely used, especially in the production of vegetarian capsules. Traditional capsule shells are mostly made of gelatin, but due to the problem of animal sources, HPMC has become an ideal alternative material. The capsule shell made of HPMC not only has good biocompatibility, but also meets the needs of vegetarians.
Liquid preparations
Due to its excellent thickening and suspension properties, CMC is widely used in liquid preparations such as oral solutions, eye drops and topical preparations. CMC can increase the viscosity of liquid preparations, thereby improving the suspension and stability of drugs and preventing drug sedimentation.
The application of HPMC in liquid preparations is mainly concentrated in thickeners and emulsifiers. HPMC can remain stable over a wide pH range and can be compatible with a variety of drugs without affecting the efficacy of the drugs. In addition, the film-forming properties of HPMC are also used in topical preparations, such as the film-forming protective effect in eye drops.
Controlled release preparations
In controlled release preparations, the application of HPMC is particularly prominent. HPMC is able to form a gel network, and the release rate of the drug can be controlled by adjusting the concentration and structure of HPMC. This property has been widely used in oral sustained-release tablets and implants. In contrast, CMC is less used in controlled-release preparations, mainly because the gel structure it forms is not as stable as HPMC.
Stability and compatibility
CMC has poor stability at different pH values and is easily affected by acid-base environments. In addition, CMC has poor compatibility with certain drug ingredients, which may cause drug precipitation or failure.
HPMC shows good stability over a wide pH range, is not easily affected by acid-base, and has excellent compatibility. HPMC can be compatible with most drug ingredients without affecting the stability and efficacy of the drug.
Safety and regulations
Both CMC and HPMC are considered safe pharmaceutical excipients and have been approved for use in pharmaceutical preparations by pharmacopoeias and regulatory agencies in various countries. However, during use, CMC may cause some allergic reactions or gastrointestinal discomfort, while HPMC rarely causes adverse reactions.
CMC and HPMC have their own advantages in pharmaceutical applications. CMC occupies an important position in liquid preparations due to its excellent thickening and suspension properties, while HPMC has been widely used in tablets, capsules and controlled-release preparations due to its excellent film-forming and controlled-release properties. The selection of pharmaceutical preparations should be based on the specific drug properties and preparation requirements, comprehensively considering the advantages and disadvantages of both, and selecting the most suitable excipient.
Post time: Jul-19-2024