Depot Injections
A depot injection is an injection, usually subcutaneous or intramuscular, of a pharmacological agent which releases its active compound in a consistent way over a long period of time. Depot injections are usually either solid or oil-based. Depot injections may be available as certain forms of a drug, such as decanoate salts or esters. Examples of depot injections include Depo Provera.
The advantages of using a long-acting depot injection include increased compliance due to reduction in the frequency of dosing, as well as more consistent serum concentrations. However, one significant disadvantage of using a depot injection is that the drug is not immediately reversible, since it is slowly released.