Most inactivated vaccines, like influenza, are given by IM injection. Some medications are formulated for IM injection, like epinephrine autoinjectors. Medical professionals are trained to give IM injections, but patients can also be trained to self-administer medications like epinephrine. In a subcutaneous injection (SubQ injections), the medication is delivered to the tissues between the skin and the muscle. Absorption of the medicine is slower than that of intramuscular injection. Since the needle does not need to reach the muscles, often a bigger gauge and shorter needle is used. Usual site of administration is fat tissues behind the arm. Certain intramuscular injection medicines such as EpiPen® can also be used subcutaneously. Insulin injection is a common type of subcutaneous injection medicine. Certain vaccines including the MMR vaccine (measles, mumps, rubella), varicella vaccine (chickenpox), and zoster vaccine (shingles) are given subcutaneously. In an intradermal injection, medication is delivered directly into the dermis, the layer just below the epidermis of the skin. The injection is often given at a 5 to 15 degree angle with the needle placed almost flat against the patient's skin. Absorption takes the longest from this route compared to intravenous, intramuscular, and subcutaneous injections. Because of this, intradermal injection are often used for sensitivity tests, like tuberculin and allergy tests, and local anesthesia tests. The reactions caused by these tests are easily seen due to the location of the injections on the skin. Common sites of intradermal injections are the forearm and lower back. A depot injection is an injection, usually subcutaneous, intradermal, or intramuscular, that deposits a drug in a localized mass, called a depot, from which it is gradually absorbed by surrounding tissue. Such injection allows the active compound to be released in a consistent way over a long period. 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 and haloperidol decanoate. Prostate cancer patients receiving hormone therapy usually get depot injections as a treatment or therapy. Zoladex is an example of a medication delivered by depot for prostate cancer treatment or therapy. Naltrexone may be administered in a monthly depot injection to control opioid abuse; in this case, the depot injection improves compliance by replacing daily pill administration.