What are the properties and requirements of the softgel contents?

Soft capsules can be filled with various oils or liquid medicines or suspensions that do not dissolve gelatin, and can also be filled with solid medicines. It is also common to fill the suspension of solid drugs in soft capsules, and the drug powder in it is at least sieved with an 80-mesh sieve. The dispersion medium or PEG400 of the suspension should also be added with a suspending agent. The suspending agent added for oily bases is 2-10% paraffin mixture, and 1-15% PEG6000 is often used for non-oily bases. In the process of pelletizing, continuous stirring is required, which improves the accuracy of loading and keeps the content uniformity within 1-2%.

(1) Water-soluble contents
The water-soluble content needs to rely on solid dispersion technology. The functional substance can be made into powder by freeze-drying, dispersed in PEG with a molecular weight of 400-4000 to form a slurry, and then coated with gelatin to form a soft capsule. The soft capsule made of PEG400 has a relatively fast drying process. If the time is too long, the capsule will rupture, and if it is too short, the soft capsule will leak during the storage period. In addition, PEG400 has a hardening effect on the rubber shell, adding 5-10% glycerol or propylene glycol can reduce the hardness and improve the water effect of PEG400 on the rubber shell. If 2% or 3% PEG600 or PVP30 is used instead of PEG400, temperature-dependent sol denaturation below 40°C can be prevented. 

(2) Water-insoluble content
Insoluble in water pharmaceutical oil, commonly used vegetable oil, disperse and dissolve and add surfactant or other absorption enhancer to make soft capsule, the drug in it is dispersed in the oil in molecular state, and the oil phase in the body is due to the surface active agent. It can spontaneously form an emulsion and enter the blood through the lymph, which is not affected by the first-pass effect, thus resulting in higher bioavailability. Using surfactants such as polyglycerol ester and sucrose ester to make soft capsules can achieve high efficiency and high safety. For example, the bioavailability of erythromycin stearate after adding polyglycerol ester is also higher than that of ordinary preparations. several times higher.