2.3 Used as thickener and suspending agent

The suspending agent is a viscous gel substance with hydrophilicity, which can slow down the sedimentation speed of the particles when used in the suspending agent, and it can be attached to the surface of the particles to prevent the particles from aggregating and shrinking into a ball. Suspending agents play a vital role in making suspensions.
HPMC is an excellent variety of suspending agents, and its dissolved colloidal solution can reduce the tension of the liquid-solid interface and the free energy on small solid particles, thereby enhancing the stability of the heterogeneous dispersion system.

2.4 Used as capsule material

Oral drug capsules are one of the traditional dosage forms. In the past, gelatin sponge was an important capsule material for capsules, and gelatin hollow capsules were relatively simple to make and widely used. However, the capsule shell has many deficiencies, such as the capsule shell is sensitive to oxygen and humidity, and gelatin capsules may cause adverse reactions such as reduced drug dissolution and prolonged rupture time.

2.5 As a slow and controlled release material for oral preparations

HPMC with a higher viscosity can be used as a controlled-release agent and retarder for hydrogel matrix sustained-release tablets; HPMC with a lower viscosity is usually used as a pore-forming agent for sustained-release or controlled-release tablets. HPMC dissolves into a gel layer in water, and the drug is released through the matrix after the gel layer is eroded and dispersed.
In clinical application, the half-life of aciclovir is very short and the curative effect is low. In order to enhance the curative effect of the drug and increase the release time of the drug, Wu Ningping et al. used polyacrylic acid and HPMC as a hydrogel-type skeleton material to make acyclovir slow release tablet. The results showed that the effect of the drug can be increased to 12 hours, and the frequency of taking the drug and the occurrence of adverse reactions have been reduced [3].

2.6 Used as a film material for oral preparations

HPMC can be combined with 1,2-propanediol and PVA for oral preparation film. Wang Tongshun and others studied licorice zinc and amlexanox, selected 100mgHPMC, 6500mgPVA, and 6000mg1,2-propanediol as the best formula, and observed the relevant indicators of the film.
In the skin transdermal absorption test, both licorice zinc and amlexanox were in the skin, and the drug that could penetrate the skin was less, and the dosage of the two drugs was in a stable state as the application time increased. The study pointed out that licorice zinc and amlexanox can penetrate the skin and exert a partial drug effect on the surface of the ulcer, further improving the healing of the ulcer and improving the curative effect.

3 Summary

HPMC is widely used in pharmaceuticals, and it can be used as suspending agent, adhesive, disintegrant, thickener, film coating material, capsule material, etc. With the rapid development of biopharmaceutical technology, it is firmly believed that HPMC plays a vital role in new drug dosage forms and drug delivery systems.