intramuscular, subcutaneous, intravenous, and intradermal<unk>  are classified in multiple ways, including the type of tissue being injected into, the location in the body the<unk> is designed to produce effects, and the duration of the effects. Regardless of classification,<unk>  require a puncture to be made, thus requiring sterile environments and procedures to minimize the risk of introducing pathogens into the body. All<unk>  are considered forms of parenteral administration, which avoids the first pass metabolism which would potentially affect a medication absorbed through the gastrointestinal tract. Systemic Many<unk>  are designed to administer a medication which has an effect throughout the body. Systemic<unk>  may be used when a person cannot take medicine by mouth, or when the medication itself would not be absorbed into circulation from the gastrointestinal tract. Medications administered via a systemic<unk> will enter into blood circulation, either directly or indirectly, and thus will have an effect on the entire body. Intravenous Intravenous<unk> , abbreviated as IV, involve inserting a needle into a vein, allowing a substance to be delivered directly into the bloodstream. An intravenous<unk> provides the quickest onset of the desired effects because the substance immediately enters the blood, and is quickly circulated to the rest of the body. Because the substance is administered directly into the bloodstream, there is no delay in the onset of effects due to the absorption of the substance into the bloodstream. This type of<unk> is the most common and is used frequently for administration of medications in an inpatient setting. Another use for intravenous<unk>  includes for the administration of nutrition to people who cannot get nutrition through the digestive tract. This is termed parenteral nutrition and may provide all or only part of a person's nutritional requirements. Parenteral nutrition may be pre-mixed or customized for a person's specific needs. Intravenous<unk>  may also be used for recreational drugs when a rapid onset of effects is desired. Intramuscular Intramuscular<unk> , abbreviated as IM, deliver a substance deep into a muscle, where they are quickly absorbed by the blood vessels into systemic circulation. Common<unk> sites include the deltoid, vastus lateralis, and ventrogluteal muscles. Medical professionals are trained to give IM<unk> , but people who are not medical professionals can also be trained to administer medications like epinephrine using an autoinjector in an emergency. Some depot<unk>  are also administered intramuscularly, including medroxyprogesterone acetate among others. In addition to medications, most inactivated vaccines, including the influenza vaccine, are given as an IM<unk>  Subcutaneous Subcutaneous<unk> , abbreviated as SC or sub-Q, consist of<unk> g a substance into the fat tissue between the skin and the muscle. Absorption of the medicine from this tissue is slower than in an intramuscular<unk>  Since the needle does not need to penetrate to the level of the muscle, a thinner and shorter needle can be used. Subcutaneous<unk>  may be administered in the fatty tissue behind the upper arm, in the abdomen, or in the thigh. Certain medications, including epinephrine, may be used either intramuscularly or subcutaneously. Others, such as insulin, are almost exclusively injected subcutaneously. Live or attenuated vaccines, including the MMR vaccine (measles, mumps, rubella), varicella vaccine (chickenpox), and zoster vaccine (shingles) are also injected subcutaneously. Intradermal A tuberculin sensitivity test being administered intradermally Intradermal<unk> , abbreviated as ID, consist of a substance delivered into the dermis, the layer of skin above the subcutaneous fat layer, but below the epidermis or top layer. An intradermal<unk> is administered with the needle placed almost flat against the skin, at a 5 to 15 degree angle. Absorption from an intradermal<unk> takes longer than when the<unk> is given intravenously, intramuscularly, or subcutaneously. For this reason, few medications are administered intradermally. Intradermal<unk>  are most commonly used for sensitivity tests, including tuberculin skin tests and allergy tests, as well as sensitivity tests to medications a person has never had before. The reactions caused by tests which use intradermal<unk> are more easily seen due to the location of the<unk>  and when positive will present as a red or swollen area. Common sites of intradermal<unk>  include the forearm and lower back. Intraosseous An intraosseous<unk> or infusion is the act of administering medication through a needle inserted into the bone marrow of a large bone. This method of administration is only used when it is not possible to maintain access through a less invasive method such as an intravenous line, either due to frequent loss of access due to a collapsed vessel, or due to the difficulty of finding a suitable vein to use in the first place. Intraosseous access is commonly obtained by inserting a needle into the bone marrow of the humerus or tibia, and is generally only considered once multiple attempts at intravenous access have failed, as it is a more invasive method of administration than an IV. With the exception of occasional differences in the accuracy of blood tests when drawn from an intraosseous line, it is considered to be equivalent in efficacy to IV access. It is most commonly used in emergency situations where there is not ample time to repeatedly attempt to obtain IV access, or in younger people for whom obtaining IV access is more difficult. Localized<unk>  may be performed into specific parts of the body when the medication's effects are desired to be limited to a specific location, or where systemic administration would produce undesirable side effects which may be avoided by a more directed<unk> <unk>  to the corpus cavernosum of the penis, termed intracavernous<unk> , may be used to treat conditions which are localized to the penis. They can be self-administered for erectile dysfunction prior to intercourse or used in a healthcare setting for emergency treatment for a prolonged erection with an<unk> to either remove blood from the penis or to administer a sympathomimetic medication to reduce the erection. Intracavernosal<unk>  of alprostadil may be used by people for whom other treatments such as PDE5 inhibitors are ineffective or contraindicated. Other medications may also be administered in this way, including papaverine, phentolamine, and aviptadil. The most common adverse effects of intercavernosal<unk>  include fibrosis and pain, as well as hematomas or bruising around the<unk> site. Medications may also be administered by<unk> g them directly into the vitreous humor of the eye. This is termed an intravitreal<unk>  and may be used to treat endophthalmitis (an<unk> of the inner eye), macular degeneration, and macular edema. An intravitreal<unk> is performed by<unk> g a medication through the pupil into the vitreous humor core of the eye after applying a local anesthetic drop to numb the eye and a mydriatic drop to dilate the pupil. They are commonly used in lieu of systemic administration to both increase the concentrations present in the eye, as well as avoid systemic side effects of medications. When an effect is only required in one joint, a joint<unk> (or intra-articular<unk>  may be administered into the articular space surrounding the joint. These<unk>  can range from a one-time dose of a steroid to help with pain and inflammation to complete replacement of the synovial fluid with a compound such as hyaluronic acid. The<unk> of a steroid into a joint is used to reduce inflammation associated with conditions such as osteoarthritis, and the effects may last for up to 6 months following a single<unk>  Hyaluronic acid<unk> is used to supplement the body's natural synovial fluid and decrease the friction and stiffness of the joint. Administering a joint<unk> generally involves the use of an ultrasound or other live imaging technique to ensure the<unk> is administered in the desired location, as well as to reduce the risk of damaging surrounding tissues. Long-acting Long-acting injectable (LAI) formulations of medications are not intended to have a rapid effect, but instead release a medication at a predictable rate continuously over a period of time. Both depot<unk>  and solid injectable implants are used to increase adherence to therapy by reducing the frequency at which a person must take a medication. Depot A depot<unk> is an<unk>  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<unk> allows the active compound to be released in a consistent way over a long period. Depot<unk>  are usually either oil-based or an aqueous suspension. Depot<unk>  may be available as certain salt forms of a drug, such as decanoate salts or esters. Examples of depot<unk>  include haloperidol decanoate, medroxyprogesterone acetate, and naltrexone. Implant<unk>  may also be used to insert a solid or semi-solid into the body which releases a medication slowly over time. These implants are generally designed to be temporary, replaceable, and ultimately removed at the end of their use or when replaced. There are multiple contraceptive implants marketed for different active ingredients, as well as differing duration of action - most of these
Injection 
Deep clean 
Implant 
Subcutaneous injection
Intradermal injection
Intramuscular injection
Depot injection
Transfusion medicine