Autoinjector

[citation needed] Automatic syringes are known since the 1910s,[2] and many spring-loaded devices with needle protectors were patented in the first half of the 20th century,[3] but it was not until 1970s when they became economically feasible to mass-produce (simple syrettes were used instead before).

[citation needed] Since spent autoinjectors contain a hypodermic needle, they pose a potential biohazard to waste management workers.

[citation needed] 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.

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.