The Empty capsules are typically composed of medicinal gelatin or other materials, and are generally digestible. Capsule-form medications can effectively cover the unpleasant odor of the drug. By encapsulating the medicine within a shell, it is isolated from external environmental factors such as moisture, air, and light, thereby enhancing the stability of the medication.
The outer shells of capsules are predominantly manufactured using medicinal gelatin; however, modern formulations also incorporate high-molecular materials such as methyl cellulose, calcium alginate (or its sodium salt), polyvinyl alcohol, and denatured gelatin to modify the solubility characteristics of the capsules. Within the gastrointestinal tract, the capsule shell can be readily decomposed by digestive enzymes in the stomach. Furthermore, the drugs contained within the capsule are typically filled in powder or granular form, allowing for rapid dissolution, dispersion, and absorption in the gastrointestinal tract, with an onset time faster than that of traditional dosage forms like pills or tablets.
Capsule-form medications can be formulated into sustained-release granules as required, achieving a controlled slow-release effect. Additionally, if enteric-coated capsules are utilized, they can ensure healthy delivery of the medication to the intended site of action.