Injections are generally administered as a bolus dose, but can also be used for continuous drug administration as well.The medication may be released slowly to be long-acting even when administered as a bolus, which is called a depot injection. If medication is to be administered long-term or with many repeated doses, use of an indwelling catheter is generally preferred.

Injections are among the most common health care procedures, with at least 16 billion administered in developing and...