Autoinjector

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A military autoinjector in use Autoinjector.jpg
A military autoinjector in use

An autoinjector (or auto-injector) is a medical device designed to deliver a dose of a particular drug. The injectors were initially designed to overcome the hesitation associated with self-administration of the needle-based drug delivery device.

Contents

Most autoinjectors are one-use, disposable, spring-loaded syringes (prefilled syringes). By design, autoinjectors are easy to use and are intended for self-administration by patients, or administration by untrained personnel. The site of injection depends on the drug loaded, but it typically is administered into the thigh or the buttocks.

Autoinjectors are sharps waste.

History

Automatic syringes are known since the 1910s, [1] and many spring-loaded devices with needle protectors were patented in the first half of the 20th century, [2] but it was not until 1970s when they became economically feasible to mass-produce (simple syrettes were used instead before). In 2023 an open source autoinjector was developed that could be digitally replicated with a low cost desktop 3D printer. [3] It was tested against the then current standard (ISO 11608–1:2022) [4] for needle-based injection systems and found to cost less than mass manufactured systems. [3]

Design

Components of a Humira autoinjector pen Components of an Adalimumab-Humira pen - annotated.jpg
Components of a Humira autoinjector pen

Designs exist for both intramuscular and subcutaneous injection. Disposable autoinjectors commonly use a pre-loaded spring as a power source. This spring and the associated mechanical components form a one-shot linear actuator. When triggered the actuator drives a three-step sequence:

  1. accelerate the syringe forward, puncturing the injection site
  2. actuate the piston of the syringe, injecting the drug
  3. deploy a shield to cover the needle

Some injectors are triggered by simply pushing the nose ring against the injection site. In these designs, the protective cap is the primary safety. Other designs use a safety mechanism similar to nail guns: The injection is triggered by pushing the nose ring against the injection site and simultaneously, while applying pressure, pushing a trigger button at the rear end of the device.

Since spent autoinjectors contain a hypodermic needle, they pose a potential biohazard to waste management workers. Hence the protective cap is designed not only to protect the drug and keep the needle sterile but also to provide adequate sharps waste confinement after disposal.

Injectors intended for application through layers of clothing may feature an adjustable injection depth. Other typical features include: A drug inspection window, a color-coded spent indicator, and an audible click after the injection has finished.

Uses

A variety of autoinjectors in use with the US Armed Forces AutoinjectorMarkI.jpg
A variety of autoinjectors in use with the US Armed Forces

Military uses include:

Variants

An injection of Auvi-Q autoinjector

Another design has a shape and size of a smartphone which can be put into a pocket. This design also has a retractable needle and automated voice instructions to assist the users on how to correctly use the autoinjector. The "Auvi-Q" epinephrine autoinjector uses this design. [7]

A newer variant of the autoinjector is the gas jet autoinjector, which contains a cylinder of pressurized gas and propels a fine jet of liquid through the skin without using a needle. This has the advantage that patients who fear needles are more accepting of using these devices. The autoinjector can be reloaded, and various doses or different drugs can be used, although the only widespread application to date has been for the administration of insulin in the treatment of diabetes. [8] [9]

See also

Related Research Articles

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<span class="mw-page-title-main">Local anesthetic</span> Medications to reversibly block pain

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An epinephrine autoinjector is a medical device for injecting a measured dose or doses of epinephrine (adrenaline) by means of autoinjector technology. It is most often used for the treatment of anaphylaxis. The first epinephrine autoinjector was brought to market in 1983.

<span class="mw-page-title-main">Hypodermic needle</span> 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.

<span class="mw-page-title-main">Subcutaneous administration</span> Insertion of medication under the skin

Subcutaneous administration is the insertion of medications beneath the skin either by injection or infusion.

<span class="mw-page-title-main">Intramuscular injection</span> 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.

Needle sharing is the practice of intravenous drug-users by which a needle or syringe is shared by multiple individuals to administer intravenous drugs such as heroin, steroids, and hormones. This is a primary vector for blood-borne diseases which can be transmitted through blood. People who inject drugs (PWID) are at an increased risk for Hepatitis C (HCV) and HIV due to needle sharing practices. From 1933 to 1943, malaria was spread between users in the New York City area by this method. Afterwards, the use of quinine as a cutting agent in drug mixes became more common. Harm reduction efforts including safe disposal of needles, supervised injection sites, and public education may help bring awareness on safer needle sharing practices.

<span class="mw-page-title-main">Injection (medicine)</span> 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.

<span class="mw-page-title-main">Syrette</span>

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<span class="mw-page-title-main">Sharps waste</span> Form of biomedical waste

Sharps waste is a form of biomedical waste composed of used "sharps", which includes any device or object used to puncture or lacerate the skin. Sharps waste is classified as biohazardous waste and must be carefully handled. Common medical materials treated as sharps waste are hypodermic needles, disposable scalpels and blades, contaminated glass and certain plastics, and guidewires used in surgery.

<span class="mw-page-title-main">Drug injection</span> Method of introducing a drug

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<span class="mw-page-title-main">Mark I NAAK</span> Dual-chamber autoinjector

In the United States military, the Mark I NAAK, or MARK I Kit, is a dual-chamber autoinjector: Two anti-nerve agent drugs—atropine sulfate and pralidoxime chloride—each in injectable form, constitute the kit. The kits are only effective against the nerve agents tabun (GA), sarin (GB), soman (GD) and VX.

Dental anesthesia is the application of anesthesia to dentistry. It includes local anesthetics, sedation, and general anesthesia.

<span class="mw-page-title-main">Charles Pravaz</span>

Charles Gabriel Pravaz a French orthopedic surgeon, pioneered the hypodermic syringe.

<span class="mw-page-title-main">Injection port</span> Medical device

An injection port is a medical device used for the administration of insulin or other physician-approved medicine into the subcutaneous tissue. The device is similar to infusion sets used by insulin pumps, except it is configured to receive a syringe instead of a tubing system. An injection port is usually a disposable device applied by the patient and worn for period of 3–5 days. When giving shots via an injection port, the needle stays above the surface of the skin. Medication is delivered via a short soft cannula. An injection port can be used in conjunction with multiple daily injections of insulin by people with diabetes. It can also be used for the subcutaneous administration of any other physician prescribed medication.

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A low dead space syringe (LDSS) or low dead-volume syringe is a type of syringe with a design that seeks to limit dead space that exists between the syringe hub and needle.

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<span class="mw-page-title-main">Injector pen</span> 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.

References

  1. GB 143084A Improvements in and relating to self-acting syringes for hypodermic injections
  2. "Espacenet – search results".
  3. 1 2 Selvaraj, Anjutha; Kulkarni, Apoorv; Pearce, J. M. (2023-07-14). "Open-source 3-D printable autoinjector: Design, testing, and regulatory limitations". PLOS ONE. 18 (7): e0288696. Bibcode:2023PLoSO..1888696S. doi: 10.1371/journal.pone.0288696 . ISSN   1932-6203. PMC   10348544 . PMID   37450496.
  4. "ISO 11608-1:2022". ISO. Retrieved 2023-09-18.
  5. May, A.; Leone, M.; Áfra, J.; Linde, M.; Sándor, P. S.; Evers, S.; Goadsby, P. J. (2006). "EFNS guidelines on the treatment of cluster headache and other trigeminal-autonomic cephalalgias". European Journal of Neurology. 13 (10): 1066–77. doi: 10.1111/j.1468-1331.2006.01566.x . PMID   16987158. S2CID   9432289.
  6. Baren, Jill M.; Rothrock, Steven G.; Brennan, John; Brown, Lance (2007-10-24). Pediatric Emergency Medicine. Elsevier Health Sciences. p. 1069. ISBN   978-1437710304.
  7. Thomas, Katie (1 February 2013). "Brothers Develop New Device to Halt Allergy Attacks". New York Times. Retrieved 6 March 2017.
  8. "1". Mendosa.com. 2001-01-16. Retrieved 2010-07-07.
  9. 2 Archived April 11, 2007, at the Wayback Machine