Bolus (medicine)

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In medicine, a bolus (from Latin bolus , ball) is the administration of a discrete amount of medication, drug, or other compound within a specific time, generally 1–30 minutes, [1] to raise its concentration in blood to an effective level. The administration can be given by injection: intravenously, intramuscularly, intrathecally, subcutaneously, or by inhalation.[ clarification needed ] The article on routes of administration provides more information, as the preceding list of ROAs is not exhaustive.



The placement of the bolus dose depends on the systemic levels of the contents desired throughout the body. An intramuscular injection of vaccines allows for a slow release of the antigen to stimulate the body's immune system and to allow time for developing antibodies. Subcutaneous injections are used by heroin addicts (called 'skin popping', referring to the bump formed by the bolus of heroin), to sustain a slow release that staves off withdrawal symptoms without producing euphoria. [2]

A bolus delivered directly to the veins through an intravenous drip allows a much faster delivery which quickly raises the concentration of the substance in the blood to an effective level. This is typically done at the beginning of a treatment or after a removal of medicine from blood (e.g. through dialysis).


Diabetics and health care professionals use bolus to refer to a dosage of fast-acting insulin with a meal (as opposed to basal rate, which is a dose of slow-acting insulin or the continuous pumping of a small quantity of fast-acting insulin to cover the glucose output of the liver). [3]

Veterinary medicine

In veterinary medicine a bolus is a large time-release tablet that stays in the rumen of cattle, goats, and sheep. It can also refer to a dose of liquid injected subcutaneously with a hypodermic needle, such as saline solution administered either to counteract dehydration or especially to mitigate kidney failure, a common ailment in domestic cats. Before it is fully absorbed, which can take several minutes or longer, the liquid remains in the form of a bolus, a ball or lump under the animal's skin.

Radiation therapy

In radiation therapy, bolus is a waxy tissue equivalent material placed on the skin surface to homogenize or modulate the range of the dose from external beams of radiation.

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Insulin pump Medical device to administer insulin

An insulin pump is a medical device used for the administration of insulin in the treatment of diabetes mellitus, also known as continuous subcutaneous insulin therapy. The device configuration may vary depending on design. A traditional pump includes:

Intensive insulin therapy or flexible insulin therapy is a therapeutic regimen for diabetes mellitus treatment. This newer approach contrasts with conventional insulin therapy. Rather than minimize the number of insulin injections per day, the intensive approach favors flexible meal times with variable carbohydrate as well as flexible physical activities. The trade-off is the increase from 2 or 3 injections per day to 4 or more injections per day, which was considered "intensive" relative to the older approach. In North America in 2004, many endocrinologists prefer the term "flexible insulin therapy" (FIT) to "intensive therapy" and use it to refer to any method of replacing insulin that attempts to mimic the pattern of small continuous basal insulin secretion of a working pancreas combined with larger insulin secretions at mealtimes. The semantic distinction reflects changing treatment.

Diabetic ketoacidosis Medical condition

Diabetic ketoacidosis (DKA) is a potentially life-threatening complication of diabetes mellitus. Signs and symptoms may include vomiting, abdominal pain, deep gasping breathing, increased urination, weakness, confusion and occasionally loss of consciousness. A person's breath may develop a specific "fruity" smell. Onset of symptoms is usually rapid. People without a previous diagnosis of diabetes may develop DKA as the first obvious symptom.

Syringe Medical injection device

A syringe is a simple reciprocating pump consisting of a plunger that fits tightly within a cylindrical tube called a barrel. The plunger can be linearly pulled and pushed along the inside of the tube, allowing the syringe to take in and expel liquid or gas through a discharge orifice at the front (open) end of the tube. The open end of the syringe may be fitted with a hypodermic needle, a nozzle or tubing to direct the flow into and out of the barrel. Syringes are frequently used in clinical medicine to administer injections, infuse intravenous therapy into the bloodstream, apply compounds such as glue or lubricant, and draw/measure liquids.

Intravenous therapy Medication administered into a vein

Intravenous therapy is a medical technique that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutrients for those who cannot, or will not—due to reduced mental states or otherwise—consume food or water by mouth. It may also be used to administer medications or other medical therapy such as blood products or electrolytes to correct electrolyte imbalances. Attempts at providing intravenous therapy have been recorded as early as the 1400s, but the practice did not become widespread until the 1900s after the development of techniques for safe, effective use.

Hypodermic needle Device to inject substances into the circulatory system

A hypodermic needle, one of a category of medical tools which enter the skin, called sharps, is a very thin, hollow tube with one sharp tip. It is commonly used with a syringe, a hand-operated device with a plunger, to inject substances into the body or extract fluids from the body. Large-bore hypodermic intervention is especially useful in catastrophic blood loss or treating shock.

Route of administration Path by which a drug, fluid, poison, or other substance is taken into the body

A route of administration in pharmacology and toxicology is the way by which a drug, fluid, poison, or other substance is taken into the body.

Subcutaneous injection Injection under the skin

A subcutaneous injection is administered as a bolus into the subcutis, the layer of skin directly below the dermis and epidermis, collectively referred to as the cutis. The instruments are usually a hypodermic needle and a syringe. Subcutaneous injections are highly effective in administering medications such as insulin, morphine, diacetylmorphine and goserelin. Subcutaneous administration may be abbreviated as SC, SQ, subcu, sub-Q, SubQ, or subcut.Subcut is the preferred abbreviation to reduce the risk of misunderstanding and potential errors.

Intramuscular injection Medical injection into a muscle

Intramuscular injection, often abbreviated IM, is the injection of a substance into a muscle. In medicine, it is one of several methods for parenteral administration of medications. Intramuscular injection may be preferred because muscles have larger and more numerous blood vessels than subcutaneous tissue, leading to faster absorption than subcutaneous or intradermal injections. Medication administered via intramuscular injection is not subject to the first-pass metabolism effect which affects oral medications.

Injection (medicine) Method of medication administration

An injection is the act of administering a liquid, especially a drug, into a person's body using a 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 intraperitoneal, intraosseous, intracardiac, intraarticular, and intracavernous injections.

Xylazine Equine medication

Xylazine is an analogue of clonidine and an agonist at the α2 class of adrenergic receptor. It is used for sedation, anesthesia, muscle relaxation, and analgesia in animals such as horses, cattle and other non-human mammals. Veterinarians also use xylazine as an emetic, especially in cats.

An insulin analog is any of several types of insulin (medication) that are altered forms of the hormone insulin, different from any occurring in nature, but still available to the human body for performing the same action as human insulin in terms of controlling blood glucose levels in diabetes. Through genetic engineering of the underlying DNA, the amino acid sequence of insulin can be changed to alter its ADME characteristics. Officially, the U.S. Food and Drug Administration (FDA) refers to these agents as insulin receptor ligands, although they are usually just referred to as insulin analogs or even just insulin.

Drug injection Method of introducing a drug

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. 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.

Dosage forms are pharmaceutical drug products in the form in which they are marketed for use, with a specific mixture of active ingredients and inactive components (excipients), in a particular configuration, and apportioned into a particular dose. For example, two products may both be amoxicillin, but one is in 500 mg capsules and another is in 250 mg chewable tablets. The term unit dose can also sometimes encompass non-reusable packaging as well, although the FDA distinguishes that by unit-dose "packaging" or "dispensing". Depending on the context, multi(ple) unit dose can refer to distinct drug products packaged together, or to a single drug product containing multiple drugs and/or doses. The term dosage form can also sometimes refer only to the pharmaceutical formulation of a drug product's constituent drug substance(s) and any blends involved, without considering matters beyond that. Because of the somewhat vague boundaries and unclear overlap of these terms and certain variants and qualifiers within the pharmaceutical industry, caution is often advisable when conversing with someone who may be unfamiliar with another person's use of the term.

Insulin glulisine Rapid-acting insulin analogue

Insulin glulisine is a rapid-acting insulin analogue that differs from human insulin in that the amino acid asparagine at position B3 is replaced by lysine and the lysine in position B29 is replaced by glutamic acid. It was developed by Sanofi-Aventis and is sold under the trade name Apidra. When injected subcutaneously, it appears in the blood earlier than human insulin. When used as a meal time insulin, the dose is to be administered within 15 minutes before or 20 minutes after starting a meal. Intravenous injections may also be used for extreme hyperglycemia, but must be performed under the supervision of a medical professional.

Insulin (medication) Use of insulin protein and analogs as medical treatment

As a medication, insulin is any pharmaceutical preparation of the protein hormone insulin that is used to treat high blood glucose. Such conditions include type 1 diabetes, type 2 diabetes, gestational diabetes, and complications of diabetes such as diabetic ketoacidosis and hyperosmolar hyperglycemic states. Insulin is also used along with glucose to treat hyperkalemia. Typically it is given by injection under the skin, but some forms may also be used by injection into a vein or muscle. There are various types of insulin, suitable for various time spans. The types are often all called insulin in the broad sense, although in a more precise sense, insulin is identical to the naturally occurring molecule whereas insulin analogues have slightly different molecules that allow for modified time of action. It is on the World Health Organization's List of Essential Medicines. In 2019, regular human insulin was the 298th most commonly prescribed medication in the United States, with more than 1 million prescriptions.

Intradermal injection Medical injection into the dermis

Intradermal injection, often abbreviated ID, is a shallow or superficial injection of a substance into the dermis, which is located between the epidermis and the hypodermis. This route of administration is relatively rare compared to injections into the subcutaneous tissue or muscle. Due to the more complex use, ID injections are not the preferred route of administration for injection and therefore used for certain therapies only, such as tuberculosis tests and allergy tests. Specific benefits are a higher immune responses for vaccinations, immunology and novel cancer treatments and faster drug uptake, since for certain small and well soluble proteins or molecules, ID route of administration is associated with fast uptake systemically compared to subcutaneous injections, applied in novel closed loop insuline infusion systems. Additionally, the body's reaction to substances is more easily visible since it is closer to the surface.

Insulin degludec Ultralong-acting basal insulin analogue

Insulin degludec (INN/USAN) is an ultralong-acting basal insulin analogue that was developed by Novo Nordisk under the brand name Tresiba. It is administered via subcutaneous injection once daily to help control the blood sugar level of those with diabetes. It has a duration of action that lasts up to 42 hours, making it a once-daily basal insulin, that is one that provides a base insulin level, as opposed to the fast- and short-acting bolus insulins.

Pharmacokinetics of estradiol

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Injector pen Drug storage and delivery device

An injector pen is a device used for injecting medication under the skin. First introduced in the 1980s, injector pens are designed to make injectable medication easier and more convenient to use, thus increasing patient adherence. The primary difference between injector pens and traditional vial and syringe administration is the easier use of an injector pen by people with low dexterity, poor vision, or who need portability to administer medicine on time. Injector pens also decrease the fear or adversity towards self-injection of medications, which increases the likelihood that a person takes the medication.


  1. "intravenous bolus". Farlex dictionary, in turn citing Mosby's Medical Dictionary, 9th edition. Retrieved 2017-07-30.
  2. "HIV/AIDS Program: Muscling and skin popping". Seattle and King County Public Health Department. 2003-11-19. Archived from the original on 2002-06-12. Retrieved 2007-10-30.
  3. "Insulin Pump Terminology". 2007. Archived from the original on 2007-07-06. Retrieved 2007-07-13.