What are the characteristics of pellets as sustained and controlled release carriers?

Pellets refer to spherical preparations with a diameter less than 2.5 mm. In order to achieve different therapeutic purposes, pharmaceutical preparations can be made into pellets with different release rates (immediate release, sustained release or controlled release) by different prescriptions, and the prepared pellets can generally be filled into empty capsules for use. In recent years, with the development of modern pellet technology, there are more and more applications in long-acting and controlled-release preparations, which mainly have the following characteristics: ① After taking it, it can be evenly distributed in the gastrointestinal tract, increasing the distribution area of drugs on the surface of the gastrointestinal tract, thereby improving bioavailability or reducing gastrointestinal irritation caused by excessive local concentration of drugs; ② Gastrointestinal absorption is less affected by gastric emptying, with uniform absorption and little difference in bioavailability among individuals; ③ Good fluidity, convenient for packaging and dosage distribution.