There are various types of capsules, and in this article, we mainly focus on two types – HPMC capsules and gelatin capsules.
According to the research, in any dissolution medium having a pH of less than or equal to 5.8, the HPMC (Hydroxypropyl methylcellulose) capsule shell dissolves rapidly and there is no difference in the time at which dissolution occurs during the test temperature interval of 10 to 55 °C. Typically, gelatin and PEG capsule shells do not dissolve at temperatures below 30 °C. In the mixed phosphate buffer at pH = 6.8, the shell dissolution time of all of the test capsules was prolonged and varied more. It was found that the addition of enzymes (pepsin, trypsin) to any dissolution medium did not enhance the difference between the different types of capsules studied. In fact, the results indicate that the capsule formulation should not be taken with a carbonated cola-type beverage. Capsules containing gelatin should preferably be administered with a warm drink, while HPMC capsules can be given a cold drink or a hot drink. For the formulation taken in the fasted state, the latter type of capsule should also be preferred. Short-term storage of gelatin-containing capsules in hot, humid tropical conditions does not appear to alter the solubility properties of the shell, and changes in the disintegration time and dissolution time of the formulations filled in such capsules may reflect changes in the incorporated powder instead of a capsule shell. However, the brief storage of HPMC capsules under these conditions appears to affect the capsule shell matrix.
In general, qualified capsules should be completely dissolved within 15 minutes of shaking in water at 37 ° C, which is similar to the dissolution time of ordinary tablets. Therefore, in general, it can dissolve quickly in the body temperature environment.
When the environment is "dry", the water content of the gelatin capsule exceeds 10%. It increases rapidly when soaked in a humid environment. It takes about 10-20 minutes for the matrix to soften, twist and decompose.
Vegetarian capsules (modified cellulose) start with less than 10% water and slowly hydrate 30-60 minutes before disintegration.
By the way, here is one thing we can sure that the water temperature we take capsules with has little effect on the release and efficacy of the medicine. The reason is that whether using cold water or hot water, the capsule is mostly in an environment of about 37 ° C.
