She told you where it would be if this ever happened, didn't she? You run to her bedside table, fling open the drawer, and grab the compact purple and yellow injector. After you pull off the lid, the device speaks, telling you to place the plastic case on your friend's thigh, press down, and dispense the life-saving drug inside. You do what it says, and a few seconds later, your friend's eyes open wide. She's alive.

That's the scenario pharmaceutical company Kaleo envisioned when it developed the Evzio auto-injector. The phone-sized gadget is new, but the drug it administers—naloxone—is an old and inexpensive chemical that works immediately to reverse the effects of opioid overdoses. In 2014, it got FDA approval and hit the market for a list price of $575, an exciting new tool to battle the country's overwhelming opioid epidemic.