There are 8 specifications and qualities of empty hard capsules, the most commonly used ones are 0~5, and the volume is from large to small as the number increases from small to large. The preparation process of its capsules is sol-dipping glue (blank making-drying-extraction-cutting-finishing. It also includes the following processes.

Material handling and filling: medicines with good fluidity can be filled directly after crushing. Drugs with poor fluidity can be directly filled with auxiliary materials such as diluents and lubricants or filled after being made into granules.

Filling and sealing: According to the bulk density of the material to be filled, calculate the volume (filling amount) of the dose to be filled, select the specifications of the empty capsule, fill the capsule body with the drug, and fit the capsule cap. Locking capsules do not need to be sealed; non-locking capsules (with flat openings) must be sealed.

The preparation methods of soft capsules are commonly used drop method and pressing method. During preparation, the capsule wall of the soft capsule needs to have plasticity and elasticity and is generally composed of gelatin, plasticizer, water, and the like. If the utilization of plasticizer is too low (or too high), the capsule wall will be too hard or too soft).

Its capsule core fluid (ie filler) is mostly liquid. When the capsule core fluid is prepared by suspending solid drug powder in an oily or non-oily liquid medium (such as PEG400), the amount of stored liquid medium can be calculated using the word "matrix adsorption".

There are two ways to prepare enteric-coated capsules. One is to react with formaldehyde to form formaldehyde gelatin that can only be dissolved in intestinal juice; the other is to coat the surface of the gelatin shell with an enteric coating.