Drug delivery refers to technology used to present a drug to a pre-determined region of the body for drug emission and absorption. Principles relating to route of administration, metabolism, site of specific targeting, and toxicity are most important within this field. Drugs administered orally (through mouth) are usually encapsulated in some structure in order to protect the drug from immune and biological responses. These structures aim to keep the drug intact until its site of action and release it at a correct dosage when exposed to a specific marker. Corn and potato starch are often used for this as they contain 60-80% amylopectin. They are mostly used in solid preparations: powders, granules, capsules, and tablets. As a natural polysaccharide, it has a compatible nature with anatomical structures and molecules. This prevents any sort of negative immune response, which is a highly controversial topic in drug delivery. Biodegradability of starch allows it to keep the drug intact until reaching its site of action. This allows the drug to avoid low pH situations such as the digestive system. Native starch can also be modified in physical, chemical, and enzymatic ways to improve mechanical or biochemical properties. Within drug delivery, physical modification include treatment under mechanical forces, heat, or pressure. Chemical modifications attempt to alter molecular structure which can include breaking or addition of bonds. Treating starch with enzymes can allow for increased water solubility.