Editing Autoinjector

{{short description|Medical drug injection device}}
[[File:Autoinjector.jpg|thumb|A military autoinjector in use]]
An '''autoinjector''' (or '''auto-injector''') is a [[medical device]] for injection of a premeasured [[Dose (biochemistry)|dose]] of a particular [[medication|drug]]. Most autoinjectors are one-use, [[Disposable product|disposable]], [[spring (device)|spring]]-loaded [[syringe]]s ('''prefilled syringes'''). By design, autoinjectors are easy to use and are intended for self-administration by patients, administration by untrained personnel, or easy use by healthcare professionals; they can also overcome the hesitation associated with self-administration using a needle.<ref>{{Cite journal |last1=Dostal P |last2=Taubel J |last3=Lorch U |last4=Aggarwal V |last5=York T |date=Jul 9, 2023 |title=The Reliability of Auto-Injectors in Clinical Use: A Systematic Review |journal=[[Cureus]] |volume=15 |issue=7 |pages=e41601 |doi=10.7759/cureus.41601 |doi-access=free |pmid=37559861 |pmc=10409493 }}</ref> The site of injection depends on the drug, but it typically is administered into the [[thigh]] or the [[buttocks]].{{Citation needed|date=August 2024}}

Autoinjectors are [[sharps waste]].{{Citation needed|date=August 2024}}

== History ==
Automatic syringes are known since  the 1910s,<ref>{{patent|GB|143084A|Improvements in and relating to self-acting syringes for hypodermic injections}}</ref> and many spring-loaded devices with needle protectors were patented in the first half of the 20th century,<ref>{{Cite web|url=https://worldwide.espacenet.com/patent/search?q=cl%20%3D%20%22A61M5%2F2033%22%20AND%20pd%20%3C%20%221950-01-01%22|title = Espacenet – search results}}</ref> but it was not until 1970s when they became economically feasible to mass-produce (simple [[syrette]]s were used instead before). In 2023 an [[Open-source hardware|open source]] autoinjector was developed that could be digitally replicated with a low cost desktop [[3D printing|3D printer]].<ref name=":0">{{Cite journal |last1=Selvaraj |first1=Anjutha |last2=Kulkarni |first2=Apoorv |last3=Pearce |first3=J. M. |date=2023-07-14 |title=Open-source 3-D printable autoinjector: Design, testing, and regulatory limitations |journal=PLOS ONE |language=en |volume=18 |issue=7 |pages=e0288696 |doi=10.1371/journal.pone.0288696 |issn=1932-6203 |pmc=10348544 |pmid=37450496 |bibcode=2023PLoSO..1888696S |doi-access=free }}</ref> It was tested against the then current standard (ISO 11608–1:2022)<ref>{{Cite web |title=ISO 11608-1:2022 |url=https://www.iso.org/standard/70733.html |access-date=2023-09-18 |website=ISO |language=en}}</ref> for needle-based injection systems and found to cost less than mass manufactured systems.<ref name=":0" />

== Design ==
[[File: Components of an Adalimumab-Humira pen - annotated.jpg|thumb|upright|Components of a [[Humira]] autoinjector pen]]

Designs exist for both [[intramuscular injection|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]].{{Citation needed|date=August 2024}} When triggered the actuator drives a three-step sequence:{{Citation needed|date=August 2024}}

# accelerate the syringe forward, puncturing the injection site
# actuate the piston of the syringe, injecting the drug
# 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 gun]]s: 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.{{Citation needed|date=August 2024}}

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 [[Sterilization (microbiology)|sterile]] but also to provide adequate sharps waste confinement after disposal.{{Citation needed|date=August 2024}}

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.{{Citation needed|date=August 2024}}

== Uses ==
[[File:AutoinjectorMarkI.jpg|right|thumb|A variety of autoinjectors in use with the [[Military of the United States|US Armed Forces]]]]

* [[Epinephrine autoinjector]]s are often prescribed to people who are at risk for [[anaphylaxis]]. Brand names include Anapen, EpiPen, Emerade, and Auvi-Q.{{Citation needed|date=August 2024}}
* Rebiject, [[Rebiject II]] and Rebidose autoinjectors for [[Rebif]], the drug for [[interferon beta-1a]] used to treat [[multiple sclerosis]].  An autoinjector for the [[Avonex]] version of this same medication is also on the market.{{Citation needed|date=August 2024}}
* SureClick autoinjector is a combination product for drugs [[Enbrel]] or [[Aranesp]] to treat [[rheumatoid arthritis]] or [[anemia]], respectively.{{Citation needed|date=August 2024}}
* [[subcutaneous injection|Subcutaneous]] [[sumatriptan]] autoinjectors are used to terminate [[cluster headache]] attacks.<ref name=EFNS>{{cite journal |doi=10.1111/j.1468-1331.2006.01566.x |pmid=16987158 |title=EFNS guidelines on the treatment of cluster headache and other trigeminal-autonomic cephalalgias |journal=European Journal of Neurology |volume=13 |issue=10 |pages=1066–77 |year=2006 |last1=May |first1=A. |last2=Leone |first2=M. |last3=Áfra |first3=J. |last4=Linde |first4=M. |last5=Sándor |first5=P. S. |last6=Evers |first6=S. |last7=Goadsby |first7=P. J. |s2cid=9432289 |doi-access=free }}</ref>
* Naloxone autoinjectors are being developed and prescribed to recreational opioid users to counteract the deadly effects of opioid overdose.[https://www.empr.com/home/news/fda-approves-naloxone-auto-injector-as-countermeasure-to-high-potency-opioids/]

Military uses include:

* Autoinjectors are often used in the military to protect personnel from [[chemical warfare]] agents. In the [[United States Military|U.S. military]], [[atropine]] and 2-PAM-Cl ([[pralidoxime chloride]]) are used for [[first aid]] ("buddy aid" or "self aid") against [[nerve agents]]. An issue item, the [[Mark I NAAK]] (Nerve Agent Antidote Kit), provides these drugs in the form of two separate autoinjectors. A newer model, the [[ATNAA]] (Antidote Treatment Nerve Agent Auto-Injector), has both drugs in one syringe, allowing for the simplification of administration procedures. In the [[Gulf War]], accidental and unnecessary use of [[atropine]] autoinjectors supplied to [[Israel]]i civilians proved to be a major medical problem.<ref>{{Cite book|url=https://books.google.com/books?id=4XcatTO8dVUC&q=gulf+war+israeli+autoinjector&pg=PA1069|title=Pediatric Emergency Medicine|last1=Baren|first1=Jill M.|last2=Rothrock|first2=Steven G.|last3=Brennan|first3=John|last4=Brown|first4=Lance|date=2007-10-24|publisher=Elsevier Health Sciences|isbn=978-1437710304|pages=1069|language=en}}</ref>
* In concert with the [[Mark I NAAK]], [[diazepam]] (''[[Valium]]'') autoinjectors, known as [[Diazepam#CANA|CANA]], are carried by US service members.{{Citation needed|date=August 2024}}

== Variants ==
[[File:Auvi-Q Injection.webm|thumb|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.<ref>{{cite news|last1=Thomas|first1=Katie|title=Brothers Develop New Device to Halt Allergy Attacks|url=https://www.nytimes.com/2013/02/02/business/auvi-q-challenges-epipen-with-a-new-shape-and-size.html|access-date=6 March 2017|work=New York Times|date=1 February 2013}}</ref>

A newer variant of the autoinjector is the gas [[Jet injector|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]].<ref>{{cite web|url=http://www.mendosa.com/injector.htm |title=1 |publisher=Mendosa.com |date=2001-01-16 |access-date=2010-07-07}}</ref><ref>[http://www.diabetes.org/uedocuments/rg05injectors.pdf 2] {{webarchive |url=https://web.archive.org/web/20070411053514/http://www.diabetes.org/uedocuments/rg05injectors.pdf |date=April 11, 2007 }}</ref>

== See also ==

* [[Syrette]]
* [[Injector pen]]

== References ==
{{commonscat|Autoinjectors}}

{{reflist}}

{{Dosage forms|state=expanded}}

[[Category:Medical equipment]]
[[Category:Drug delivery devices]]