The device for anaphylaxis shock was first designed for use in the military. Its simple design has allowed the EpiPen to dominate the auto-injector market.

Anyone following the recent pricing controversy over the EpiPen might be surprised to learn that its inventor never collected a penny in royalties.

Sheldon Kaplan first invented the ComboPen, an auto-injector filled with nerve gas antidote, for the U.S military in the 1970s.

Around the same time, he developed a similar device for civilians facing their own enemy: anaphylaxis.

Greek for “without protection,” anaphylaxis is a severe allergic reaction that occurs when the body launches a full-scale attack on a seemingly innocuous substance like a peanut or a latex glove.

French physiologist — and eugenicist and paranormal researcher — Charles Richet was awarded the Nobel Prize in 1913 for describing and naming the phenomenon, which he studied by injecting dogs with jellyfish venom.

In the most serious version of anaphylaxis, the body’s blood pressure plummets and the airways close off, meaning that a person can go from eating dinner to fighting for their life within minutes.

With the EpiPen, a treatment for anaphylaxis is always close at hand.

Read more: Rising cost of EpiPen forcing allergy sufferers to switch to syringes »

Epinephrine, or adrenaline, constricts and patches leaky blood vessels, which raises blood pressure and opens airways back up.

A Japanese-American biochemist named Jokichi Takamine is generally credited with the discovery of adrenaline, which he announced around the turn of the 20th century. Takamine is also responsible for Washington D.C.’s famous cherry trees, a gift he arranged from the mayor of Tokyo.

Soon after his discovery, scientists figured out how to synthesize and produce the hormone cheaply. The drug enjoyed a brief career as a panacea, used to treat everything from bubonic plague to bed-wetting.

Eventually, adrenaline (which came to be known as epinephrine in the United States) settled into its role as a surgical aid, a treatment for asthma, and a means of reversing anaphylaxis.

Just in time, too. Beginning around the 1960s, anaphylaxis seemed to be happening more often — not just in clinical settings as a reaction to medicine.

As a result, doctors began prescribing epinephrine kits, stocked with a vial of medicine and syringes, to at-risk patients.

Read more: Parents urging states to require epinephrine auto-injectors »

When the EpiPen was approved by the Food and Drug Administration (FDA) in 1987, it was met with a sigh of relief from needle-averse patients and their families.

Kaplan’s design releases a spring-loaded syringe pre-filled with a dose of adrenaline. It’s designed to be delivered through a person’s clothing — eliminating the time-consuming act of filling a syringe and requiring no medical expertise beyond a short tutorial.

Although Kaplan’s name was listed on the patent, he never received royalties for the invention, which belonged instead to his employer, Survival Technology Inc.

The EpiPen changed hands several times, eventually landing at the now-vilified pharmaceutical company Mylan in 2007.

Mylan quickly launched a full tilt marketing and advocacy campaign aimed at getting schools to stock EpiPens, an effort galvanized by the high-profile deaths of several schoolchildren.

In 2013, President Obama signed the School Access to Emergency Epinephrine Act, which provides financial incentives to schools that keep epinephrine auto-injectors on hand.

Although the bill doesn’t refer to the EpiPen brand specifically, Mylan has come under fire for allegedly restricting schools’ access to competing auto-injectors, few though they may be.

Read more: Parents want all ambulances to carry EpiPens »

The AuviQ, a smaller and more discreet auto-injector, equipped with a voice function that talked a patient through its deployment, was recalled in 2015 for delivering inconsistent doses of the drug.

Another option, Twinject, has also been discontinued.

Adrenaclick is the only other auto-injector still available to consumers. It retails for about a quarter of the price of the EpiPen and its manufacturer also makes a generic version. Mylan announced several weeks ago that it will be pushing through its own generic.

But as the first and longest-lasting auto-injector on the market, doctors and patients alike have come to trust the EpiPen brand over any other device.

Also, change can be more than just inconvenient in an emergency situation.

The Adrenaclick is deployed a little differently, so a person using it for the first time would have to re-orient themselves to unfamiliar instructions.

Until the FDA wades through a backlog of other auto-injector applications — or until a novel delivery system like an under-the-tongue tablet is approved — epinephrine technology seems to have stalled.

Some doctors are now suggesting patients cut costs by carrying kits composed of epinephrine and syringes, a system that Kaplan, who died in 2009, must have thought would be relegated to the history books.