Empty hard capsules are two-piece shells, consisting of a cap and a body, that are widely used in the nutraceutical and pharmaceutical industries to deliver powders, granules, pellets, or even certain liquids in a convenient dosage form. They are tasteless, odorless, and easy to swallow, making them a preferred choice for consumers while allowing manufacturers to precisely control dosage and formulation. These capsules come in different types based on material and function. By material, the most common are gelatin capsules, made from animal-derived gelatin, and vegetarian alternatives such as HPMC (Hydroxypropyl Methylcellulose), pullulan from natural fermentation, and starch-based options. By function, capsules may be designed for immediate release in the stomach, enteric-coated to dissolve only in the intestines, or sustained/controlled release for gradual delivery of active ingredients; some hard capsules are also made for liquid or oil-based fillings. In addition, they are available in a range of sizes, from the largest size 000 to the smallest size 5, with sizes 0, 00, and 1 being the most commonly used in dietary supplements. Overall, empty hard capsules offer flexibility, stability, and consumer-friendly delivery, making them a key technology in modern supplement formulation.
