Any ingredient intentionally added to a drug or biologic that is not intended to have a therapeutic effect but may improve product delivery. Examples of excipients are diluents to increase the weight or volume of tablets, flavoring agents in chewable or disintegrating tablets, a coating solution for bad-smelling tablets, sustained-release excipients, and coloring agents. Excipients can also be used to improve drug safety, help maintain drug integrity during storage, and move the drug to the part of the body where it is needed.