The Ludwig von Mises Institute (Economy Institute) has recently written an article about the lack of EpiPen Competitiors. It provides a good summary:
EpiPen is sold by Mylan, and the price for a pack of two has increased
from about $100 in 2007 to over $600 as of May 2016. (...) With the
FDA, patents, and cozy insurance relationships, Mylan has been able to
steadily increase the price of EpiPens without significant market
repercussions.
Epinephrine is extremely cheap—just a few cents per dose. The
complications come from producing the easy auto-injecting devices.
Mylan “owns” their auto-injector device design, so competitors must
find work-arounds in their devices to deliver the epinephrine into the
patient’s body.
A French pharmaceutical company offered an electronic device that
actually talks people through the steps of administering the drug, but
it was recalled because of concerns about it delivering the required
dose. Just this year, Teva Pharmaceutical’s attempt at bringing a
generic epinephrine injector to market in the US was blocked by the
FDA. Adrenaclick and Twinject were unable to get insurance companies
on board and so discontinued their injectors in 2012.
Adrenaclick has since come back, but it is still not covered by many
insurance plans, and the FDA has made it illegal for pharmacies to
substitute Adrenaclick as a generic alternative to EpiPen. Another
company tried to sidestep the whole auto-injector patent barrier by
offering prefilled syringes, but the FDA has stalled them, too.
https://mises.org/blog/lack-epipen-competitors-fdas-fault
Here another source in the NY Times which provides some insights too:
http://www.nytimes.com/2016/08/25/business/mylan-raised-epipens-price-before-the-expected-arrival-of-a-generic.html?_r=0