Cellulose ethers are widely used in the pharmaceutical industry, and their unique physical and chemical properties make them an important component of a variety of pharmaceutical preparations.

1. Controlled and sustained release preparations
Cellulose ethers, such as hydroxypropyl methylcellulose (HPMC) and sodium carboxymethyl cellulose (CMC-Na), are often used to control the release rate of drugs. They can form a gel layer to extend the release time of drugs by regulating the diffusion rate and dissolution rate of drugs. By using cellulose ethers with different viscosities and degrees of substitution, the release rate of drugs in the body can be precisely controlled, thereby improving drug efficacy and reducing the frequency of medication.

2. Forming of capsules and tablets
Cellulose ethers play a key role in the manufacturing process of tablets and capsules as binders and forming agents. HPMC and CMC-Na are often used as binders for direct tableting due to their good fluidity and compressibility. They can increase the hardness and toughness of tablets, improve the mechanical strength of tablets, and ensure proper disintegration of tablets in the gastrointestinal tract.

3. Thickeners and stabilizers
Cellulose ethers are used as thickeners and stabilizers in liquid preparations. They can increase the viscosity of the solution and improve the suspension and stability of the drug. For example, CMC-Na is often used in oral suspensions and topical creams to prevent the sedimentation and stratification of drug ingredients, thereby improving the uniformity and stability of the preparation.

4. Enteric coating materials
Certain cellulose ethers, such as ethyl cellulose (EC), are often used in enteric coating materials due to their tolerance to acidic environments. Enteric coatings can protect the drug from decomposition in gastric acid and release the drug in the intestine. This can prevent the drug from being destroyed in the stomach and improve the bioavailability of the drug.

5. Bioadhesive materials
Cellulose ethers can adhere to biological membranes, which makes them important in the preparation of bioadhesive preparations. Bioadhesive preparations can prolong the residence time of drugs at the site of action and increase the local concentration of drugs, thereby enhancing the efficacy of drugs. For example, HPMC is often used in ophthalmic preparations and oral mucosal preparations, which can increase the residence time of drugs on the ocular surface and oral mucosa.

6. Coating materials
Cellulose ethers are often used as coating materials to control the release characteristics of drugs and improve the stability of drugs. Cellulose ether coatings can protect drugs from external environmental influences, such as moisture and oxygen, and extend the shelf life of drugs. In addition, by adjusting the coating thickness and formulation, the drug can be released at a fixed time and in a targeted manner.

7. Enhancers and suspending agents
In some complex drug preparations, cellulose ethers can be used as enhancers and suspending agents to improve the efficacy and stability of drugs. For example, in injectable drugs and intravenous infusions, cellulose ethers can prevent the sedimentation of drug particles and improve the uniformity and stability of the drug solution.

8. Functional excipients
Cellulose ethers are also used to prepare functional excipients, such as fast-dissolving tablets and sustained-release tablets. These excipients can adjust the dissolution rate and release characteristics of drugs, improve the bioavailability of drugs and patient compliance. For example, HPMC is widely used to prepare fast-dissolving tablets, which can quickly disintegrate after contact with water, making it easier for patients to take.

9. Biocompatibility and safety
Cellulose ether has good biocompatibility and safety, and can be metabolized into harmless substances in the body, reducing side effects on the human body. Therefore, cellulose ether is widely used in the pharmaceutical industry and has become an ideal excipient for a variety of drug preparations.

The application of cellulose ether in the pharmaceutical industry covers controlled-release and sustained-release preparations, capsule and tablet molding, thickeners and stabilizers, enteric coating materials, bioadhesive materials, coating materials, synergists and suspending agents. Its unique physical and chemical properties make it an indispensable and important ingredient in pharmaceutical preparations, which has greatly promoted the development of pharmaceutical technology and the improvement of drug efficacy.