EpiPen

Overview
EpiPen is a registered trademark for the most commonly used autoinjector of epinephrine (a.k.a. adrenaline), used in medicine to treat anaphylactic shock. CaH13No3

Description
EpiPen is manufactured by DEY L.P. EpiPens are commonly carried by persons with severe allergies and a risk of anaphylactic shock because they can be self-administered and are very fast-acting. In the UK and US, EpiPens are regulated medical devices and require a prescription. In Canada, EpiPens may be purchased without a prescription, but they are kept behind pharmacy counters.

The standard dosage of epinephrine supplied by an EpiPen is 0.3 ml of 1 in 1000 Parts (0.3 mg). Child-sized dosages (0.15 mg) are available as the EpiPen JR. In the US, EpiPen JR is recommended for children 33-66 lb., while in Canada it is recommended for children 15 to 30kg. 

The EpiPen contains a spring-loaded needle that shoots through a membrane in the tip and into the recipient's body to deliver the medication. There are two valid sets of instructions for use as of the present. In the new set of instructions, approved by the Government’s Medicines and Healthcare products Regulatory Agency (UK), a patient uses the device by removing the gray locking cap from the top of the device, forming a fist around the unit, and jabbing it firmly into a thigh until the click of the spring-loaded needle activating is heard. These instructions are assumed to be more intuitive than the old instructions, in which after the locking cap was removed, the device was put to the injection site and then pressure was applied to activate the mechanism. Both sets of instructions are valid, but all EpiPens manufactured since December 2004 carry the new instructions. Regardless of the instruction version, after activation the patient holds the device in place for 10 seconds as the epinephrine is delivered. This gives the drug enough time to be absorbed by the body's muscles and diffused into the bloodstream. Using the device intravenously is highly discouraged, and can even be lethal as epinephrine is a local vascular constrictor, and use intravenously can restrict blood flow to the area of the injection site, causing subsequent damage to extremities. Additionally, intravenous administration of the EpiPen can cause ventricular tachycardia, or dangerously rapid heartbeat, due to the tendency of epinephrine to accelerate the heartbeat of the patient. (It would be exceedingly difficult to use an EpiPen intravenously, so this warning is moot.)

After administering the device, the company's lawyers advise patients to seek immediate medical attention. Patients with experience—who carry preloaded syringes of epinephrine, diphenhydramine, and dexamethasone—can generally go home instead of the emergency room. However, these are not EpiPen customers.

EpiPen usually has a shelf life of 20 months, when the EpiPen should be discarded if unused,by returning it to a local pharmacy or hospital for safe disposal. Using an EpiPen that has expired is discouraged but better than nothing in an emergency. The original carrying tube that the pen came in was easily broken; however, the manufacturer has recently begun shipping EpiPens in more durable carrying tubes with significantly thicker plastic walls, a screw top, and metal plating at the bottom (needle) end to prevent puncture injuries.

Despite being trademarked, common usage of the word "epipen" is drifting toward the generic context of any epinephrine autoinjector.

Alternatives
Companies other than Dey have begun to market similar devices, such as the Twinject. Ampules of epinephrine are also available for single use in physician offices and hospital pharmacies, as are preloaded Tubex cartridges. None of these devices prevents future episodes of anaphylaxis, but patients who experience severe or life-threatening reactions may be treated with a series of allergy injections composed of increasing concentrations of naturally occurring substances such as venom to provide excellent and usually life-long protections against adverse affects of future insect stings: these injections are astonishingly dilute—a billion-fold or more is common.