Capsules in medicine refer to capsules made of special film-forming materials, such as gelatin, cellulose, and polysaccharides. These capsules contain various drugs in powder or liquid form, which are meant to be swallowed. Drugs packed in capsules are generally powders or granules that can irritate the esophagus and gastric mucosa, taste bad, volatilize easily, decompose in saliva, or be inhaled into the trachea. By packing these medications into capsules, their properties are protected from degradation and they are prevented from damaging the digestive organs and respiratory tract. Removing the capsule shell may result in drug loss, waste, and reduced efficacy. In addition, some drugs require dissolution and absorption in the intestines, which is facilitated by the use of capsules that protect the drugs from being destroyed by gastric acid.

      Capsules can be divided into soft and hard types, with empty capsules typically referring to the latter. Empty capsules are generally made from different raw materials. The most commonly available empty capsules on the market are gelatin and vegetarian capsules. There are also glutinous rice capsules, but they are relatively rare due to their high production cost. Gelatin capsules are mainly made from animal skin and bones, with pig skin being the most commonly used. However, some companies also produce cow and sheep capsules, which are also considered halal capsules. Vegetarian capsules, on the other hand, are made from natural plants and primarily use medicinal hydroxypropyl methylcellulose (HPMC) as the main raw material. Compared to gelatin capsules, plant capsules have the advantages of stable properties, no brittleness under low humidity, stable capsule shell under high humidity, wide storage conditions, and no need to add any preservatives in the production process.

      The HPMC in vegetarian capsules is chemically stable and does not react with air or water, nor does it undergo cross-linking reactions with some drugs. It has wide adaptability, stable drug release speed, complete dissolution, and a more significant therapeutic effect with small individual differences. After HPMC is made into the capsule shell, it retains its natural composition, and there is no need to add any preservatives during the production process. In contrast, gelatin capsules are prone to bacterial and microbial growth, requiring the addition of preservatives during production, which can result in paraben preservative residues, epoxy ethanol, chlorohydrin residues, and so on.

      Vegetarian capsules do not become brittle under low humidity conditions and can keep the capsule shell stable under high humidity conditions. They have wider storage conditions, and their temperature can be maintained between 10-40°C with a humidity between 35-65% without softening, deformation, or hardening. In contrast, gelatin capsules lose water and harden under low humidity conditions, while under high humidity conditions, capsules stick together, requiring more stringent storage and transportation conditions. HPMC is metabolically inert, is not absorbed in the body, and is directly excreted from the body. Vegetarian capsules are not easily prone to microbial growth and do not decompose or deteriorate over time, with a typical shelf life of 36 months.

      The identification of vegetarian capsules is also simple. When the capsule shell is ignited, it produces a burning cotton smell, whereas gelatin capsules produce a protein-burning odor similar to burning hair.

      When choosing empty capsules, it is important to consider the specific needs of the medication and the preferences or dietary restrictions of the patient. Gelatin capsules are widely used and generally less expensive, but they are not suitable for vegetarians, vegans, or those who follow halal or kosher dietary restrictions.

      In addition, empty capsules can also be customized in size and color to meet the specific needs of different drugs and manufacturers. For example, some drugs require a larger dosage and therefore need larger capsules, while others may require smaller capsules for easier swallowing. Furthermore, some manufacturers may want their capsules to match their branding or packaging, and so may choose to have them produced in specific colors.

      It is important to note that while empty capsules can be filled with various substances, it is crucial to ensure that the contents are safe and appropriate for consumption. It is also important to follow proper handling and storage procedures for both filled and empty capsules to maintain their quality and effectiveness.

      In conclusion, empty capsules play an important role in the pharmaceutical industry by providing a safe and effective way to deliver medicines to patients. With advances in technology and production methods, there are now more options available, such as vegetarian capsules, that offer additional benefits and appeal to a wider range of consumers. As such, it is important for healthcare professionals and consumers alike to be aware of the different types of capsules available and their respective properties to ensure the best possible treatment outcomes.