First pass effect in the context of "Drug injection"

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⭐ Core Definition: First pass effect

The first pass effect (FPE), also known as first-pass metabolism (FPM) or presystemic metabolism, is a phenomenon of drug metabolism at a specific location in the body which leads to a reduction in the concentration of the active drug before it reaches the site of action or systemic circulation. The effect is most associated with orally administered medications, but some drugs still undergo first-pass metabolism even when delivered via an alternate route (e.g., IV, IM, etc.). During this metabolism, drug is lost during the process of absorption which is generally related to the liver and gut wall. The liver is the major site of first pass effect; however, it can also occur in the lungs, vasculature or other metabolically active tissues in the body.

Notable drugs that experience a significant first pass effect are buprenorphine, chlorpromazine, cimetidine, diazepam, ethanol (drinking alcohol), imipramine, insulin, lidocaine, midazolam, morphine, pethidine, propranolol, and tetrahydrocannabinol (THC).

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👉 First pass effect in the context of Drug injection

Drug injection is a method of introducing a drug into the bloodstream via a hollow hypodermic needle, which is pierced through the skin into the body (usually intravenously, but also at an intramuscular or subcutaneous, location). Intravenous therapy, a form of drug injection, is universally practiced in modernized medical care. As of 2004, there were 13.2 million people worldwide who self-administered injection drugs outside of medical supervision, of which 22% are from developed countries.

A wide variety of drugs are injected, often opioids: these may include legally prescribed medicines and medication such as morphine, as well as stronger compounds often favored in recreational drug use, which are often illegal. Ketamine administered intravenously in clinical settings has become more common. Although there are various methods of taking drugs, injection is favoured by some people as the full effects of the drug are experienced very quickly, typically in five to ten seconds. It also bypasses first-pass metabolism in the liver, resulting in higher bioavailability and efficiency for many drugs (such as morphine or diacetylmorphine/heroin; roughly two-thirds of which is destroyed in the liver when consumed orally) than oral ingestion would. The effect is that the person gets a stronger (yet shorter-acting) effect from the same amount of the drug. Drug injection is therefore often related to substance dependence.

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First pass effect in the context of Injection (medicine)

An injection (often and usually referred to as a "shot" in US English, a "jab" in UK English, or a "jag" in Scottish English and Scots) is the act of administering a liquid, especially a drug, into a person's body using a needle (usually a hypodermic needle) and a syringe. An injection is considered a form of parenteral drug administration; it does not involve absorption in the digestive tract. This allows the medication to be absorbed more rapidly and avoid the first pass effect. There are many types of injection, which are generally named after the body tissue the injection is administered into. This includes common injections such as subcutaneous, intramuscular, and intravenous injections, as well as less common injections such as epidural, intraperitoneal, intraosseous, intracardiac, intraarticular, and intracavernous injections.

Injections are among the most common health care procedures, with at least 16 billion administered in developing and transitional countries each year. Of these, 95% are used in curative care or as treatment for a condition, 3% are to provide immunizations/vaccinations, and the rest are used for other purposes, including blood transfusions. The term injection is sometimes used synonymously with inoculation, but injection does not only refer to the act of inoculation. Injections generally administer a medication as a bolus (or one-time) dose, but can also be used for continuous drug administration. After injection, a medication may be designed to be released slowly, called a depot injection, which can produce long-lasting effects.

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LINKED FROM (PARENTS)
← Drug injection ← Intravenous drug ← Injection (medicine)
LINKS TO (CHILDREN)
Drug metabolism → Concentration → Drug → Orally administered → Medication → Intravenous therapy → Intramuscular injection → Absorption (pharmacology) → Liver → Gut wall → Buprenorphine → Chlorpromazine → Cimetidine → Diazepam → Alcohol (drug) → Imipramine → Insulin (medication) → Lidocaine → Midazolam → Morphine → Pethidine → Propranolol → Tetrahydrocannabinol →