Hydroxypropyl cellulose, a pharmaceutical excipient, is divided into low-substituted hydroxypropyl cellulose (L-HPC) and high-substituted hydroxypropyl cellulose (H-HPC) according to the content of its substituent hydroxypropoxy. L-HPC swells into a colloidal solution in water, has the properties of adhesion, film formation, emulsification, etc., and is mainly used as a disintegrating agent and binder; while H-HPC is soluble in water and various organic solvents at room temperature, and has good thermoplasticity. , cohesiveness and film-forming properties, the formed film is hard, glossy, and fully elastic, and is mainly used as a film-forming material and coating material. The specific application of hydroxypropyl cellulose in solid preparations is now introduced.

1. As a disintegrant for solid preparations such as tablets

The surface of low-substituted hydroxypropyl cellulose crystalline particles is uneven, with obvious weathered rock-like structure. This rough surface structure not only makes it have a larger surface area, but also when it is compressed into a tablet together with drugs and other excipients, numerous pores and capillaries are formed in the tablet core, so that the tablet core can increase the moisture absorption rate and Water absorption increases swelling. Using L-HPC as an excipient can make the tablet rapidly disintegrate into a uniform powder, and significantly improve the disintegration, dissolution and bioavailability of the tablet. For example, the use of L-HPC can accelerate the disintegration of paracetamol tablets, aspirin tablets, and chlorpheniramine tablets, and improve the dissolution rate. The disintegration and dissolution of poorly soluble drugs such as ofloxacin tablets with L-HPC as disintegrants were better than those with cross-linked PVPP, cross-linked CMC-Na and CMS-Na as disintegrants. Using L-HPC as an internal disintegrant of the granules in the capsules is beneficial to the disintegration of the granules, increases the contact surface area between the drug and the dissolution medium, promotes the dissolution of the drug, and improves the bioavailability. Immediate-release solid preparations represented by fast-disintegrating solid preparations and instant-dissolving solid preparations have fast-disintegrating, instant-dissolving, fast-acting effects, high bioavailability, reduced drug irritation to the esophagus and gastrointestinal tract, and are convenient to take and have good compliance. and other advantages, occupying an important position in the field of pharmacy. L-HPC has become one of the most important excipients for immediate-release solid preparations due to its strong hydrophilicity, hygroscopicity, expansibility, short hysteresis time for water absorption, fast water absorption speed, and fast water absorption saturation. It is an ideal disintegrant for orally disintegrating tablets. Paracetamol orally disintegrating tablets were prepared with L-HPC as disintegrant, and the tablets disintegrated rapidly within 20s. L-HPC is used as a disintegrant for tablets, and its general dosage is 2% to 10%, mostly 5%.

2. As a binder for preparations such as tablets and granules

The rough structure of L-HPC also makes it have a greater mosaic effect with drugs and particles, which increases the degree of cohesion, and has good compression molding performance. After being pressed into tablets, it shows more hardness and gloss, thus improving the The quality of the tablet’s appearance. Especially for tablets that are not easy to form, loose or easy to uncover, adding L-HPC can improve the effect. The ciprofloxacin hydrochloride tablet has poor compressibility, easy to split and sticky, and it is easy to form after adding L-HPC, with suitable hardness, beautiful appearance, and the dissolution rate meets the quality standard requirements. After adding L-HPC into the dispersible tablet, its appearance, friability, dispersion uniformity and other aspects are greatly improved and improved. After the starch in the original prescription was replaced by L-HPC, the hardness of the azithromycin dispersible tablet was increased, the friability was improved, and the problems of missing corners and rotten edges of the original tablet were solved. L-HPC is used as a binder for tablets, and the general dosage is 5% to 20%; while H-HPC is used as a binder for tablets, granules, etc., and the general dosage is 1% to 5% of the preparation.

3. Application in film coating and sustained and controlled release preparations

At present, water-soluble materials commonly used in film coating include hydroxypropylmethylcellulose (HPMC), hydroxypropylcellulose, polyethylene glycol (PEG) and so on. Hydroxypropyl cellulose is often used as a film-forming agent in film coating premixing materials because of its tough, elastic and glossy film. If hydroxypropyl cellulose is mixed with other temperature-resistant coating agents, the performance of its coating can be further improved.

Using appropriate excipients and techniques to make the drug into matrix tablets, gastric floating tablets, multi-layer tablets, coated tablets, osmotic pump tablets and other slow and controlled release tablets, the significance lies in: increasing the degree of drug absorption and stabilizing the drug in the blood. Concentration, reduce adverse reactions, reduce the number of medications, and strive to maximize the curative effect with the smallest dose, and minimize adverse reactions. Hydroxypropyl cellulose is one of the main excipients of such preparations. The dissolution and release of diclofenac sodium tablets are controlled by using hydroxypropyl cellulose and ethyl cellulose as a joint and skeleton material. After oral administration and contact with gastric juice, the surface of diclofenac sodium sustained-release tablets will be hydrated into a gel. Through the dissolution of the gel and the diffusion of drug molecules in the gel gap, the purpose of slow release of drug molecules is achieved. Hydroxypropyl cellulose is used as the The controlled-release matrix of the tablet, when the content of the blocker ethyl cellulose is constant, its content in the tablet directly determines the release rate of the drug, and the drug from the tablet with a higher content of hydroxypropyl cellulose Release is slower. The coated pellets were prepared by using L-HPC and a certain proportion of HPMC as a coating solution for coating as a swelling layer, and as a controlled-release layer for coating with ethyl cellulose aqueous dispersion. When the swelling layer prescription and dosage are fixed, by controlling the thickness of the controlled release layer, the coated pellets can be released at different expected times. Several kinds of coated pellets with different weight gain of the controlled release layer are mixed to make Shuxiong sustained-release capsules. In the dissolution medium, various coated pellets can release drugs sequentially at different times, so that the components with different physical and chemical properties Simultaneous release is achieved at the same time as sustained release